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• What are some things you'd like fresh college grads to know?

  - by bradhe

  So I proposed this to the Reddit community and I'd like to get SO's perspective on this. This is pretty much the copypasta of what I put there. I was thinking about this last night and thought it would be neat to compile a list. I'm still a pretty fresh college grad -- been in industry for 2 years -- but I think that I might have a few interesting things to lend. You don't know as much as you think you do. Somehow, college students think they know a lot more than they do (or maybe that was just me). Likewise, they think they can do more than they actually can. You should fairly assess your skills. QA people are not out to get you. Humans introduce bugs to code. It's not (nescessarily) a personal reflection on you and your skills if your code has a bug and it's caught by the QA/testing team. Listen to your senior (developers). They are not actually fuddy duddies who don't know about the new L337 hax in Ruby (okay, sometimes they are, but still...). They have a wealth of knowledge that you can learn from and it's in your best interest to do so. You will most likely not be doing what you want to for a while. This is mostly true in the corporate world -- startups are a different matter. Also, this is due to more than just the economy, man! Junior devs need to earn their keep, so to speak. Everyone wants to be lead dev on the next project and there are a lot of people in line ahead of you! For every elite developer there are 100 average developers. Joel Spolsky, I'm looking at you. Somehow this concept of ninja coders has really ingrained itself in our culture. While I encourage you to be the best you can be don't be disappointed if people aren't writing blog posts about you in the near future. Anyone else have anything they would see added to this list?

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• OpenGL ES Polygon with Normals rendering (Note the 'ES!')

  - by MarqueIV

  Ok... imagine I have a relatively simple solid that has six distinct normals but actually has close to 48 faces (8 faces per direction) and there are a LOT of shared vertices between faces. What's the most efficient way to render that in OpenGL? I know I can place the vertices in an array, then use an index array to render them, but I have to keep breaking my rendering steps down to change the normals (i.e. set normal 1... render 8 faces... set normal 2... render 8 faces, etc.) Because of that I have to maintain an array of index arrays... one for each normal! Not good! The other way I can do it is to use separate normal and vertex arrays (or even interleave them) but that means I need to have a one-to-one ratio for normals to vertices and that means the normals would be duplicated 8 times more than they need to be! On something with a spherical or even curved surface, every normal most likely is different, but for this, it really seems like a waste of memory. In a perfect world I'd like to have my vertex and normal arrays have different lengths, then when I go to draw my triangles or quads To specify the index to each array for that vertex. Now the OBJ file format lets you specify exactly that... a vertex array and a normal array of different lengths, then when you specify the face you are rendering, you specify a vertex and a normal index (as well as a UV coord if you are using textures too) which seems like the perfect solution! 48 vertices but only 8 normals, then pairs of indexes defining the shapes' faces. But I'm not sure how to render that in OpenGL ES (again, note the 'ES'.) Currently I have to 'denormalize' (sorry for the SQL pun there) the normals back to a 1-to-1 with the vertex array, then render. Just wastes memory to me. Anyone help? I hope I'm missing something very simple here. Mark

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• How to add Items to GridView in C# Windows Store App (Win8)

  - by flexage

  To keep things simple let's just say I have a c# Windows Store Project for Windows 8 that has the following items: GridView (PlatformsGrid) List«PlatformSearchResult» (allPlatforms) DataTemplate (PlatformDataTemplate) in standardstyles.xaml allPlatforms is a collection of "PlatformSearchResult"objects populated from an online API, and has the following 3 properties: ID Name Alias I am able to add a new item to the gridview for each object that exists in my allPlatforms collection, however the items are blank and do not show the data from my objects. A quick summary of the current code looks like this: XAML Markup: <!-- Platforms Content --> <GridView x:Name="PlatformsGrid" Grid.Row="1" CanReorderItems="True" CanDragItems="True" ItemTemplate="{StaticResource PlatformDataTemplate}" > <GridView.ItemsPanel> <ItemsPanelTemplate> <WrapGrid MaximumRowsOrColumns="2" VerticalChildrenAlignment="Top" HorizontalChildrenAlignment="Center" /> </ItemsPanelTemplate> </GridView.ItemsPanel> </GridView> Data Template <!-- Platform Item Template --> <DataTemplate x:Key="PlatformDataTemplate"> <Grid Background="#FF939598" Height="250" Width="250"> <Image Source="/SampleImage.png" Stretch="UniformToFill"/> <StackPanel Orientation="Vertical" Background="#CC000000" Height="90" VerticalAlignment="Bottom"> <TextBlock Text="{Binding Name}" Margin="10,3,0,0" Width="242" Height="62" TextTrimming="WordEllipsis" TextWrapping="Wrap" HorizontalAlignment="Left"/> <TextBlock Text="{Binding Alias}" Margin="10,2,0,0" Width="186" Height="14" TextTrimming="WordEllipsis" HorizontalAlignment="Left" FontSize="9" Opacity="0.49"/> </StackPanel> </Grid> </DataTemplate> Controlling Function private async void FetchItemInfo_Loaded(object sender, RoutedEventArgs e) { // Get List of Top Games List<PlatformSearchResult> allPlatforms = new List<PlatformSearchResult>(); allPlatforms = await GamesDB.GetPlatforms(); // Dynamically Create Platform Tiles foreach (PlatformSearchResult platform in allPlatforms) { PlatformsGrid.DataContext = platform; PlatformsGrid.Items.Add(platform); } } How do I get the added items to show the appropriate object properties (ignoring the image for now), I'm just interested in populating the content of the TextBlocks. I appreciate any help anyone can provide! Thanks, Alex.

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• Generate A Simple Read-Only DAL?

  - by David

  I've been looking around for a simple solution to this, trying my best to lean towards something like NHibernate, but so far everything I've found seems to be trying to solve a slightly different problem. Here's what I'm looking at in my current project: We have an IBM iSeries database as a primary repository for a third party software suite used for our core business (a financial institution). Part of what my team does is write applications that report on or key off of a lot of this data in some way. In the past, we've been manually creating ADO .NET connections (we're using .NET 3.5 and Visual Studio 2008, by the way) and manually writing queries, etc. Moving forward, I'd like to simplify the process of getting data from there for the development team. Rather than creating connections and queries and all that each time, I'd much rather a developer be able to simply do something like this: var something = (from t in TableName select t); And, ideally, they'd just get some IQueryable or IEnumerable of generated entities. This would be done inside a new domain core that I'm building where these entities would live and the applications would interface with it through a request/response service layer. A few things to note are: The entities that correspond to the database tables should be generated once and we'd prefer to manually keep them updated over time. That is, if columns/tables are added to the database then we shouldn't have to do anything. (If some are deleted, of course, it will break, but that's fine.) But if we need to use a new column, we should be able to just add it to the necessary class(es) without having to re-gen the whole thing. The whole thing should be SELECT-only. We're not doing a full DAL here because we don't want to be able to break anything in the database (even accidentally). We don't need any kind of mapping between our domain objects and the generated entity types. The domain barely covers a fraction of the data that's in there, most of it we'll never need, and we would rather just create re-usable maps manually over time. I already have a logical separation for the DAL where my "repository" classes return domain objects, I'm just looking for a better alternative to manual ADO to be used inside the repository classes. Any suggestions? It seems like what I'm doing is just enough outside the normal demand for DAL/ORM tools/tutorials online that I haven't been able to find anything. Or maybe I'm just overlooking something obvious?

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• Improved way to build nested array of unique values in javascript

  - by dualmon

  The setup: I have a nested html table structure that displays hierarchical data, and the individual rows can be hidden or shown by the user. Each row has a dom id that is comprised of the level number plus the primary key for the record type on that level. I have to have both, because each level is from a different database table, so the primary key alone is not unique in the dom. example: id="level-1-row-216" I am storing the levels and rows of the visible elements in a cookie, so that when the page reloads the same rows the user had open are can be shown automatically. I don't store the full map of dom ids, because I'm concerned about it getting too verbose, and I want to keep my cookie under 4Kb. So I convert the dom ids to a compact json object like this, with one property for each level, and a unique array of primary keys under each level: { 1:[231,432,7656], 2:[234,121], 3:[234,2], 4:[222,423], 5:[222] } With this structure stored in a cookie, I feed it to my show function and restore the user's previous disclosure state when the page loads. The area for improvement: I'm looking for better option for reducing my map of id selectors down to this compact format. Here is my function: function getVisibleIds(){ // example dom id: level-1-row-216-sub var ids = $("tr#[id^=level]:visible").map(function() { return this.id; }); var levels = {}; for(var i in ids ) { var id = ids[i]; if (typeof id == 'string'){ if (id.match(/^level/)){ // here we extract the number for level and row var level = id.replace(/.*(level-)(\d*)(.*)/, '$2'); var row = id.replace(/.*(row-)(\d*)(.*)/, '$2'); // *** Improvement here? *** // This works, but it seems klugy. In PHP it's one line (see below): if(levels.hasOwnProperty(level)){ if($.inArray(parseInt(row, 10) ,levels[level]) == -1){ levels[level].push(parseInt(row, 10)); } } else { levels[level] = [parseInt(row, 10)]; } } } } return levels; } If I were doing it in PHP, I'd build the compact array like this, but I can't figure it out in javascript: foreach($ids as $id) { if (/* the criteria */){ $level = /* extract it from $id */; $row = /* extract it from $id */; $levels[$level][$row]; } }

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• How can I run an android frame animation without it skewing?

  - by GameDev123

  I have a small state machine that runs a series of frame by frame animations in an ImageView, in a nested hierarchy of layouts. There is more than adequate space to display each frame of the animation. Each frame of the animation is cropped to fit the minimum amount of area, in order to save memory. If a frame only contains 50x50 worth of pixels then the png is 50x50. There is no transparent padding to keep them the same size. The ImageView is directly within a RelativeLayout, and is anchored to the bottom left with some padding. The general idea being that the character in the animation performs some action, which results in individual frames of the animation growing or shrinking. The issue is that individual frames of animation are skewed, and there does not appear to be any way of preventing this. If I set the source of the imageview directly to one of the frames of animation, it displays fine in the layout manager. I have tried this with Adjust View Bounds set to true, false, and undefined. I have tried using the background and the src attribute of imageview to set the animation drawable, I have tried every configuration of layout manager and setting minimum/maximum size that I can think of, and it still stretches the character on various frames depending on the size of the source png. In essence, all I want to do is say "I want this ImageView to anchor in the bottom left and then display any frame that happens to be in it without stretching or skewing it in any way aside from that which occurred when the frame png's were loaded." Seems simple, but I have yet to come across any way of doing it. Here is the layout of the imageview as of my last test, I had to remove bits of the XML to get it to display but nothing pertinent: RelativeLayout android:orientation="horizontal" android:layout_above="@+id/MenuOptions" android:layout_width="fill_parent" android:id="@+id/AnimationLayout" android:clipChildren="false" android:minHeight="180dp" android:layout_height="fill_parent" android:layout_below="@+id/GameBarLayout" ImageView android:id="@+id/animatedImg" android:layout_height="wrap_content" android:layout_width="wrap_content" android:visibility="visible" android:baselineAlignBottom="true" android:minHeight="180dp" android:minWidth="200dp" android:adjustViewBounds="true" android:layout_alignParentBottom="true" android:paddingLeft="30dp" android:paddingBottom="10dp" android:src="@drawable/idle01"/ImageView /RelativeLayout Here is how an animation is set up: animationDrawable = new AnimationDrawable(); animationDrawable.addFrame(res.getDrawable(R.drawable.idle01), 16); animationDrawable.addFrame(res.getDrawable(R.drawable.idle02), 16); animationDrawable.addFrame(res.getDrawable(R.drawable.idle03), 16);

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• Which is the "best" data access framework/approach for C# and .NET?

  - by Frans

  (EDIT: I made it a community wiki as it is more suited to a collaborative format.) There are a plethora of ways to access SQL Server and other databases from .NET. All have their pros and cons and it will never be a simple question of which is "best" - the answer will always be "it depends". However, I am looking for a comparison at a high level of the different approaches and frameworks in the context of different levels of systems. For example, I would imagine that for a quick-and-dirty Web 2.0 application the answer would be very different from an in-house Enterprise-level CRUD application. I am aware that there are numerous questions on Stack Overflow dealing with subsets of this question, but I think it would be useful to try to build a summary comparison. I will endeavour to update the question with corrections and clarifications as we go. So far, this is my understanding at a high level - but I am sure it is wrong... I am primarily focusing on the Microsoft approaches to keep this focused. ADO.NET Entity Framework Database agnostic Good because it allows swapping backends in and out Bad because it can hit performance and database vendors are not too happy about it Seems to be MS's preferred route for the future Complicated to learn (though, see 267357) It is accessed through LINQ to Entities so provides ORM, thus allowing abstraction in your code LINQ to SQL Uncertain future (see Is LINQ to SQL truly dead?) Easy to learn (?) Only works with MS SQL Server See also Pros and cons of LINQ "Standard" ADO.NET No ORM No abstraction so you are back to "roll your own" and play with dynamically generated SQL Direct access, allows potentially better performance This ties in to the age-old debate of whether to focus on objects or relational data, to which the answer of course is "it depends on where the bulk of the work is" and since that is an unanswerable question hopefully we don't have to go in to that too much. IMHO, if your application is primarily manipulating large amounts of data, it does not make sense to abstract it too much into objects in the front-end code, you are better off using stored procedures and dynamic SQL to do as much of the work as possible on the back-end. Whereas, if you primarily have user interaction which causes database interaction at the level of tens or hundreds of rows then ORM makes complete sense. So, I guess my argument for good old-fashioned ADO.NET would be in the case where you manipulate and modify large datasets, in which case you will benefit from the direct access to the backend. Another case, of course, is where you have to access a legacy database that is already guarded by stored procedures. ASP.NET Data Source Controls Are these something altogether different or just a layer over standard ADO.NET? - Would you really use these if you had a DAL or if you implemented LINQ or Entities? NHibernate Seems to be a very powerful and powerful ORM? Open source Some other relevant links; NHibernate or LINQ to SQL Entity Framework vs LINQ to SQL

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• How to reconcile my support of open-source software and need to feed and house myself?

  - by Guzba

  I have a bit of a dilemma and wanted to get some other developers' opinions on it and maybe some guidance. So I have created a 2D game for Android from the ground up, learning and re factoring as I went along. I did it for the experience, and have been proud of the results. I released it for free as ad supported with AdMob not really expecting much out of it, but curious to see what would happen. Its been a few of months now since release, and it has become very popular (250k downloads!). Additionally, the ad revenue is great and is driving me to make more good games and even allowing me to work less so that I can focus on my own works. When I originally began working on the game, I was pretty new to concurrency and completely new to Android (had Java experience though). The standard advice I got for starting an Android game was to look at the sample games from Google (Snake, Lunar Lander, ...) so I did. In my opinion, these Android sample games from Google are decent to see in general what your code should look like, but not actually all that great to follow. This is because some of their features don't work (saving game state), the concurrency is both unexplained and cumbersome (there is no real separation between the game thread and the UI thread since they sync lock each other out all the time and the UI thread runs game thread code). This made it difficult for me as a newbie to concurrency to understand how it was organized and what was really running what code. Here is my dilemma: After spending this past few months slowly improving my code, I feel that it could be very beneficial to developers who are in the same position that I was in when I started. (Since it is not a complex game, but clearly coded in my opinion.) I want to open up the source so that others can learn from it but don't want to lose my ad revenue stream, which, if I did open the source, I fear I would when people released versions with the ad stripped, or minor tweaks that would fragment my audience, etc. I am a CS undergrad major in college and this money is giving me the freedom to work less at summer job, thus giving me the time and will to work on more of my own projects and improving my own skills while still paying the bills. So what do I do? Open the source at personal sacrifice for the greater good, or keep it closed and be a sort of hypocritical supporter of open source?

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• Why does std::map operator[] create an object if the key doesn't exist?

  - by n1ck

  Hi, I'm pretty sure I already saw this question somewhere (comp.lang.c++? Google doesn't seem to find it there either) but a quick search here doesn't seem to find it so here it is: Why does the std::map operator[] create an object if the key doesn't exist? I don't know but for me this seems counter-intuitive if you compare to most other operator[] (like std::vector) where if you use it you must be sure that the index exists. I'm wondering what's the rationale for implementing this behavior in std::map. Like I said wouldn't it be more intuitive to act more like an index in a vector and crash (well undefined behavior I guess) when accessed with an invalid key? Refining my question after seeing the answers: Ok so far I got a lot of answers saying basically it's cheap so why not or things similar. I totally agree with that but why not use a dedicated function for that (I think one of the comment said that in java there is no operator[] and the function is called put)? My point is why doesn't map operator[] work like a vector? If I use operator[] on an out of range index on a vector I wouldn't like it to insert an element even if it was cheap because that probably mean an error in my code. My point is why isn't it the same thing with map. I mean, for me, using operator[] on a map would mean: i know this key already exist (for whatever reason, i just inserted it, I have redundancy somewhere, whatever). I think it would be more intuitive that way. That said what are the advantage of doing the current behavior with operator[] (and only for that, I agree that a function with the current behavior should be there, just not operator[])? Maybe it give clearer code that way? I don't know. Another answer was that it already existed that way so why not keep it but then, probably when they (the ones before stl) choose to implement it that way they found it provided an advantage or something? So my question is basically: why choose to implement it that way, meaning a somewhat lack of consistency with other operator[]. What benefit do it give? Thanks

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• When mocking a class with Moq, how can I CallBase for just specific methods?

  - by Daryn

  I really appreciate Moq's Loose mocking behaviour that returns default values when no expectations are set. It's convenient and saves me code, and it also acts as a safety measure: dependencies won't get unintentionally called during the unit test (as long as they are virtual). However, I'm confused about how to keep these benefits when the method under test happens to be virtual. In this case I do want to call the real code for that one method, while still having the rest of the class loosely mocked. All I have found in my searching is that I could set mock.CallBase = true to ensure that the method gets called. However, that affects the whole class. I don't want to do that because it puts me in a dilemma about all the other properties and methods in the class that hide call dependencies: if CallBase is true then I have to either Setup stubs for all of the properties and methods that hide dependencies -- Even though my test doesn't think it needs to care about those dependencies, or Hope that I don't forget to Setup any stubs (and that no new dependencies get added to the code in the future) -- Risk unit tests hitting a real dependency. Q: With Moq, is there any way to test a virtual method, when I mocked the class to stub just a few dependencies? I.e. Without resorting to CallBase=true and having to stub all of the dependencies? Example code to illustrate (uses MSTest, InternalsVisibleTo DynamicProxyGenAssembly2) In the following example, TestNonVirtualMethod passes, but TestVirtualMethod fails - returns null. public class Foo { public string NonVirtualMethod() { return GetDependencyA(); } public virtual string VirtualMethod() { return GetDependencyA();} internal virtual string GetDependencyA() { return "! Hit REAL Dependency A !"; } // [... Possibly many other dependencies ...] internal virtual string GetDependencyN() { return "! Hit REAL Dependency N !"; } } [TestClass] public class UnitTest1 { [TestMethod] public void TestNonVirtualMethod() { var mockFoo = new Mock<Foo>(); mockFoo.Setup(m => m.GetDependencyA()).Returns(expectedResultString); string result = mockFoo.Object.NonVirtualMethod(); Assert.AreEqual(expectedResultString, result); } [TestMethod] public void TestVirtualMethod() // Fails { var mockFoo = new Mock<Foo>(); mockFoo.Setup(m => m.GetDependencyA()).Returns(expectedResultString); // (I don't want to setup GetDependencyB ... GetDependencyN here) string result = mockFoo.Object.VirtualMethod(); Assert.AreEqual(expectedResultString, result); } string expectedResultString = "Hit mock dependency A - OK"; }

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• Architectural Design for a Data-Driven Silverlight WP7 app

  - by Rosarch

  I have a Silverlight Windows Phone 7 app that pulls data from a public API. I find myself doing much of the same thing over and over again: In the UI, set a loading message or loading progress bar in place of where the content is Get the content, which may be already in memory, cached in isolated file storage, or require an HTTP request If the content can not be acquired (no network connection, etc), display an error message If the content is acquired, display it in the UI Keep the content in main memory for subsequent queries The content that is displayed to the user can be taken directly from a data source, such as an ObservableCollection, or it may be a query on a data source. I would like to factor out this repetitive process into a framework where ideally only the following needs to be specified: Where to display the content in the UI The UI elements to show while loading, on failure, and on success The URI of the HTTP request How to parse the HTTP response into the data structure that will kept in memory The location of the file in isolated storage, if it exists How to parse the file contents into the data structure that will be kept in memory It may sound like a lot, but two strings, three FrameworkElements, and two methods is less than the overhead that I currently have. Also, this needs to work for however the data is maintained in memory, and needs to work for direct collections and queries on those collections. My questions are: Has something like this already been implemented? Are my thoughts about the topic above fundamentally wrong in some way? Here is a design I'm thinking of: There are two components, a View and a Model. The View is given the FrameworkElements for loading, failure, and success. It is also given a reference to the corresponding Model. The View is a UserControl that is placed somewhere in the UI. The Model a class that is given the URI for the data, a method of how to parse the data, and optionally a filename and how to parse the file. It is responsible for retrieving the data and notifying the View whenever the current status (loading/fail/success) changes. If the data downloaded from the network is different from the cache, the network data takes precedence. When the app closes or is tombstoned, the model writes the data to the cache. How does that sound?

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• Using hidden values with jQuery (and ASP.NET MVC) -- not working?

  - by SlackerCoder

  Im using a couple of JSON calls to render data, etc etc. In order to keep the proper key value, I am storing it in a tag. I have this in several places in my code, none of which cause an issue like this one is. Here is the jQuery: The call that "sets" the value: $("a[id^='planSetupAddNewPlan']").live('click', function() { var x = $(this).attr('id'); x = x.substring(19); $("#hidPlanSetupCurrentGroupKey").val(x); $.getJSON("/GroupSetup/PlanSetupAddNewList", { GroupKey: x }, function(data) { $("#planSetupAddNew").html('' + data.TableResult + ''); alert('First Inside 2 ' + x); $.blockUI({ message: $("#planSetupAddNew") }); }); }); The call that "gets" the value: $("#ddlPlanSetupAddNewProduct").live('change', function() { var a = $("#hidPlanSetupCurrentGroupKey").val(); var prod = $(this).val(); alert(a); $.getJSON("/GroupSetup/PlanSetupChangePlanList", { GroupKey: a, Product: prod }, function(data) { if (data.Message == "Success") { $("#planSetupAddNewPlan").html('' + data.TableResult + ''); } else if (data.Message == "Error") { //Do something } }); }); Here is the html in question: <div id="planSetupAddNew" style="display:none; cursor: default;"> <input type="hidden" id="hidPlanSetupCurrentGroupKey" /> <div id="planSetupAddNewData"> </div> </div> In the first section, the alert ('First Inside 2 ' + x) returns what I expect (where x = the key value), and if I add a line to display the contents of the hidden field, that works as well: ie. var key = $("#hidPlanSetupCurrentGroupKey").val(); alert(key); In the "alert(a);" call, I am getting "undefined". I have looked at the other code in the same view and it is the same and it works. I must be missing something, or have some sort of mistype that I havent caught. Just an overview of the controller events: The first call (/GroupSetup/PlanSetupAddNewList) will return an html string building a "form" for users to enter information into. The second call (/GroupSetup/PlanSetupChangePlanList) just changes a second dropdown based on the first dropdown selection (overwriting the html in the div). If you need more info, let me know! Any thoughts/tips/pointers/suggestions?!?! Thanks for all your help :)

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• OutOfMemoryError loading Bitmap via DefaultHttpClient

  - by Goddchen

  i have a simple problem: Although i'm using sampleSize properly, my code doesn't even reach the BitmapFactorycode, since DefaultHttpClient is already throwing the exception. Here is my code: DefaultHttpClient client = new DefaultHttpClient(); HttpGet request = new HttpGet(mSongInfo.imageLarge); HttpResponse response = client.execute(request); int sampleSize = 1; while (response.getEntity().getContentLength() / sampleSize / sampleSize > 100 * 1024) { sampleSize *= 2; } BitmapFactory.Options options = new BitmapFactory.Options(); options.inSampleSize = sampleSize; final Bitmap bitmap = BitmapFactory.decodeStream(response .getEntity().getContent(), null, options); And here is the exception: 0 java.lang.OutOfMemoryError: (Heap Size=11463KB, Allocated=7623KB, Bitmap Size=9382KB) 1 at org.apache.http.util.ByteArrayBuffer.<init>(ByteArrayBuffer.java:53) 2 at org.apache.http.impl.io.AbstractSessionInputBuffer.init(AbstractSessionInputBuffer.java:82) 3 at org.apache.http.impl.io.SocketInputBuffer.<init>(SocketInputBuffer.java:98) 4 at org.apache.http.impl.SocketHttpClientConnection.createSessionInputBuffer(SocketHttpClientConnection.java:83) 5 at org.apache.http.impl.conn.DefaultClientConnection.createSessionInputBuffer(DefaultClientConnection.java:170) 6 at org.apache.http.impl.SocketHttpClientConnection.bind(SocketHttpClientConnection.java:106) 7 at org.apache.http.impl.conn.DefaultClientConnection.openCompleted(DefaultClientConnection.java:129) 8 at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:173) 9 at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164) 10 at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119) 11 at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:359) 12 at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555) 13 at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487) 14 at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465) 15 at de.goddchen.android.easysongfinder.fragments.SongFragment$1.run(SongFragment.java:79) 16 at java.lang.Thread.run(Thread.java:1027) As you can see, the code doesn't even reach the part where i check the size (Content-Length) of the image and calculate a proper sample size. I wasn't aware that simply calling DefaultHttpClient.execute(...) will already load the complete content into the memory. Am i doing something wrong? What is the right way to first retrieve the content length and then start reading the content from an InputStream? EDIT To avoid common answers that show how to load images from a URL: i already know how to do that, i have also posted the code above, so why do you keep referencing tutorials on that? I explicitly was very clear about the problem: Why is HttpClient.execute(...)already fetching the whole content and storing it in memory instead of providing a proper ÌnputStreamto me? Please don't post any beginner tutorials on how to load aBitmap`from a URL...

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• PHP & MySQL - saving and looping problems.

  - by R.I.P.coalMINERS

  I'm new to PHP and MySQL I want a user to be able to store multiple names and there meanings in a MySQL database tables named names using PHP I will dynamically create form fields with JQuery every time a user clicks on a link so a user can enter 1 to 1,000,000 different names and there meanings which will be stored in a table called names. Since I asked my last question I figured out how to store my values from my form using the for loop but every time I loop my values when I add one or more dynamic fields the second form field named meaning will not save the value entered also my dynamic form fields keep looping doubling, tripling and so on the entered values into the database it all depends on how many form fields are added dynamically. I was wondering how can I fix these problems? On a side note I replaced the query with echo's to see the values that are being entered. Here is the PHP code. <?php if(isset($_POST['submit'])) { $mysqli = mysqli_connect("localhost", "root", "", "site"); $dbc = mysqli_query($mysqli,"SELECT * FROM names WHERE userID='$userID'"); $name = $_POST['name']; $meaning = $_POST['meaning']; if(isset($name['0']) && mysqli_num_rows($dbc) == 0 && trim($name['0'])!=='' && trim($meaning['0'])!=='') { for($n = 0; $n < count($name); $n++) { for($m = 0; $m < count($meaning); $m++) { echo $name[$n] . '<br />'; echo $meaning[$m] . '<br /><br />'; break; } } } } ?> And here is the HTML code. <form method="post" action="index.php"> <ul> <li><label for="name">Name: </label><input type="text" name="name[]" id="name" /></li> <li><label for="meaning">Meaning: </label><input type="text" name="meaning[]" id="meaning" /></li> <li><input type="submit" name="submit" value="Save" /></li> </ul> </form> If needed I will place the JQuery code.

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• How do I use JDK 7 on Mac OSX?

  - by Yko

  OK. This is a newbie question but I can't figure it out... I would like to use the WatchService API as mentioned in this link: http://download.oracle.com/javase/tutorial/essential/io/notification.html After reading around, I found out that WatchService is part of the NIO class which is scheduled for JDK 7. So, it is in beta form. It's fine. http://jdk7.java.net/download.html has the JDK which I downloaded and extracted. I got a bunch of folders. I don't know what to do with them. Then, I read around some more and found that some nice group of people created JDK 7 as a binary so someone like me can install it easily. It is called Open JDK: http://code.google.com/p/openjdk-osx-build/ So, I downloaded the .dmg file and instal it. Then I open "Java Preference" and see that OpenJDK7 is available. So, now I feel that I can start trying out WatchService API. From the tutorial in the first link, the author gave a .java file to test it out first and make sure that it is running. Here is the link to the file: http://download.oracle.com/javase/tutorial/essential/io/examples/WatchDir.java So, I boot up Eclipse (actually I use STS) and create a new Java project and choose JaveSE-1.7 in the "use an execution environment JRE:". Under the src folder, I copy pasted the WatchDir.java file. And I still see tons of squiggly red lines. All the "import.java.nio.*" are all red and I cannot run it as a Java app. If you read this far, thanks a lot. So, now... What do I need to do? Thanks. EDIT: I actually did not pursue using Java 7 but there are a lot of interest in it and it seems like people keep answering this question. What should I do to make it more relevant to people who search for it? Let me know by PMing me. Thanks.

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• JUnit for Functions with Void Return Values

  - by RobotNerd

  I've been working on a Java application where I have to use JUnit for testing. I am learning it as I go. So far I find it to be useful, especially when used in conjunction with the Eclipse JUnit plugin. After playing around a bit, I developed a consistent method for building my unit tests for functions with no return values. I wanted to share it here and ask others to comment. Do you have any suggested improvements or alternative ways to accomplish the same goal? Common Return Values First, there's an enumeration which is used to store values representing test outcomes. public enum UnitTestReturnValues { noException, unexpectedException // etc... } Generalized Test Let's say a unit test is being written for: public class SomeClass { public void targetFunction (int x, int y) { // ... } } The JUnit test class would be created: import junit.framework.TestCase; public class TestSomeClass extends TestCase { // ... } Within this class, I create a function which is used for every call to the target function being tested. It catches all exceptions and returns a message based on the outcome. For example: public class TestSomeClass extends TestCase { private UnitTestReturnValues callTargetFunction (int x, int y) { UnitTestReturnValues outcome = UnitTestReturnValues.noException; SomeClass testObj = new SomeClass (); try { testObj.targetFunction (x, y); } catch (Exception e) { UnitTestReturnValues.unexpectedException; } return outcome; } } JUnit Tests Functions called by JUnit begin with a lowercase "test" in the function name, and they fail at the first failed assertion. To run multiple tests on the targetFunction above, it would be written as: public class TestSomeClass extends TestCase { public void testTargetFunctionNegatives () { assertEquals ( callTargetFunction (-1, -1), UnitTestReturnValues.noException); } public void testTargetFunctionZeros () { assertEquals ( callTargetFunction (0, 0), UnitTestReturnValues.noException); } // and so on... } Please let me know if you have any suggestions or improvements. Keep in mind that I am in the process of learning how to use JUnit, so I'm sure there are existing tools available that might make this process easier. Thanks!

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• Help with basic php and xml needed

  - by Matt

  Hi, I'm really new to xml, with this being my first dip into it. I'm trying to add some text to an image using php and xml. I keep getting the following error: Parse error: syntax error, unexpected '}' in /home/a8744502/public_html/userbar.php on line 18 Below is my code. <?php header ("Content-type: image/jpeg"); $doc = new DOMDocument(); $doc->load( "http://phogue.net/feed/". LIBXML_DTDLOAD ); $procon = $doc->getElementsByTagName( "procon" ); $packages = $procon->getElementsByTagName( "package" ); $value = 0; foreach($packages as $package) { $downloadsA = $package->getElementsByTagName( "downloads" ); $downloads = $downloadsA->item(0)->nodeValue; $value = $downloads + $value } $font = "visitor1.tff"; $font = 4; $im = ImageCreateFromjpeg("procon_plugindeveloper.jpg"); $x = 360; $y = 0; $background_color = imagecolorallocate ($im, 255, 255, 255); $text_color = imagecolorallocate ($im, 255, 255, 255); imagestring ($im, $font, $x, $y, $value, $text_color); imagejpeg ($im); ?> The xml file is of the form <procon> -<packages> --<package> ---<downloads> ---</doanloads> --</package> --<package> ---<downloads> ---</doanloads> --</package> --<package> ---<downloads> ---</doanloads> --</package> -</packages> </procon> The idea is that it should print out the sum of all the downloads tags that are contained in . Any help is appreciated :-)

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• Delete last 3 lines within while ((line = r.ReadLine()) != null) but not open a new text file to delete the lines?

  - by user1473672

  This is the code I've seen so far to delete last 3 lines in a text file, but it's required to determine string[] lines = File.ReadAllLines(); which is nt necessary for me to do so. string[] lines = File.ReadAllLines(@"C:\\Users.txt"); StringBuilder sb = new StringBuilder(); int count = lines.Length - 3; // except last 3 lines for (int s = 0; s < count; s++) { sb.AppendLine(lines[s]); } The code works well, but I don't wanna re-read the file as I've mentioned the streamreader above : using (StreamReader r = new StreamReader(@"C:\\Users.txt")) Im new to C#, as far as I know, after using streamreader, and if I wanna modify the lines, I have to use this : while ((line = r.ReadLine()) != null) { #sample codes inside the bracket line = line.Replace("|", ""); line = line.Replace("MY30", ""); line = line.Replace("E", ""); } So, is there any way to delete the last 3 lines in the file within the "while ((line = r.ReadLine()) != null)" ?? I have to delete lines, replace lines and a few more modications in one shot, so I can't keep opening/reading the same text file again and again to modify the lines. I hope the way I ask is understable for you guys .< Plz help me, I know the question sounds simple but I've searched so many ways to solve it but failed =( So far, my code is : using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.IO; namespace ConsoleApplication11 { public class Read { static void Main(string[] args) { string tempFile = Path.GetTempFileName(); using (StreamReader r = new StreamReader(@"C:\\Users\SAP Report.txt")) { using (StreamWriter sw = new StreamWrite (@"C:\\Users\output2.txt")) { string line; while ((line = r.ReadLine()) != null) { line = line.Replace("|", ""); line = line.Replace("MY30", ""); line = line.Replace("E", ""); line = System.Text.RegularExpressions.Regex.Replace(line, @"\s{2,}", " "); sw.WriteLine(line); } } } } } } Now my next task is to delete the last 3 lines in the file after these codes, and I need help on this one. Thank you.

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• Changing the title of jQuery-UI dialog-box with in another dialog-box's function...

  - by Brian Ojeda

  Why doesn't doesn't the second jQuery-UI dialog box title change when popped. The first dialog box I change the title of the box with using the following .attr("title", "Confirm") -- it change the title of the first box to 'Confirm', like it should have. Now when the second box pops up it should change the title to 'Message' since did the same thing for the second box -- .attr("title", "Message"). Right? But it doesnt. It keep the title from before. However, the message change like it should have. I have tested in IE8, Chrome, and FF3.6. <div id="dialog-confirm" title=""></div> <-- This is the html before jQuery functions. Javascript / jQuery $('#userDelete').click(function() { $(function() { var dialogIcon = "<span class=\"ui-icon ui-icon-alert\"></span>"; var dialogMessage = dialogIcon + "Are you sure you want to delete?"; $("#dialog-confirm").attr("title", "Confirm").html(dialogMessage).dialog({ resizable: false, height: 125, width: 300, modal: true, buttons: { 'Delete': function() { $(this).dialog('close'); $.post('user_ajax.php', {action: 'delete', aId: $('[name=aId]').val() }, function(data) { if(data.success){ var dialogIcon = "<span class=\"ui-icon ui-icon-info\"></span>"; var dialogMessage = dialogIcon + data.message; $('#dialog-confirm').attr("title", "Message"); $('#dialog-confirm').html(dialogMessage); $('#dialog-confirm').dialog({ resizable: false, height: 125, width: 300, modal: true, buttons: { 'Okay': function() { $(this).dialog('close'); var url = $_httpaddress + "admin/index.php" $(location).attr('href',url); } // End of Okay Button Function } //--- End of Dialog Button Script });//--- End of Dialog Function } else { $_messageConsole.slideDown(); $_messageConsole.html(data.message); } }, 'json'); }, //--- End of Delete Button Function 'Cancel': function() { $(this).dialog('close'); } //--- End of Cancel Button Function } //--- End of Dialog Button Script }); //--- End of Dialog Script }); //--- End of Dialog Function return false; }); Thank you for you assistant, if you choose to help.

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• How to delete empty lines in multi-ranges in Vim

  - by Kev

  I get a text file: <p>...</p> <pre> ... ... ... ... </pre> <p>...</p> <p>...</p> <p>...</p> <pre> ... ... ... </pre> <p>...</p> Notice that: there are some empty lines between [pre]...[/pre]. I want to delete them. But, I want keep those in [ p]...[/p] The text file becomes: <p>...</p> <pre> ... ... ... ... </pre> <p>...</p> <p>...</p> <p>...</p> <pre> ... ... ... </pre> <p>...</p> I use the cmd below to located them: /<pre>\n\zs\_.\{-}\ze\n<\/pre> But I don't know what to do next! I need a one-line-cmd to do this. Any idea? Thanks! The simpler, the better! Edit: Thank you all. I just figure out how to do it with the help of my another question :g/<pre>/,/<\/pre>/s/^$\n//

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• Adding a clustered index to a SQL table: what dangers exist for a live production system?

  - by MoSlo

  Right, keep in mind i need to describe this by abstracting all possible confidential info: I've been put in charge of a 10-year old transactional system of which the majority business logic is implemented at database level (triggers, stored procedures etc). Win2000 server, MSSQL 2000 Enterprise. No immediate plans for replacing/updating the system are being considered :( The core process is a program that executes transactions - specifically, it executes a stored procedure with various parameters, lets call it sp_ProcessTrans. The program executes the stored procedure at asynchronous intervals. By itself, things work fine. But there are 30 instances of this program on remotely located workstations, all of them asynchronously executing sp_ProcessTrans and then retrieving data from the SQL server (execution is pretty regular - ranging 0 to 60 times a minute, depending on what items the program instance is responsible for) . Performance of the system has dropped considerably with 10 yrs of data growth: the reason is the deadlocks and specifically deadlock wait times. The deadlock is on the Employee table. I have discovered: In sp_ProcessTrans' execution, it selects from an Employee table 7 times (dont ask) The select is done on a field that is NOT the primary key No index exists on this field. Thus a table scan is performed. 7 times. per transaction So the reason for deadlocks is clear. I created a non-unique ordered clustered index on the field (field looks good, almost unique, NUM(7), very rarely changes). Immediate improvement in the test environment. The problem is that i cannot simulate the deadlocks in a test environment (I'd need 30 workstations; i'd need to simulate 'realistic' activity on those stations, so visualization is out). I need to know if i must schedule downtime. Creating an index shouldn't be a risky operation for MSSQL, but is there any danger (data corruption in transactions/select statements/extra wait time etc) to create this field index on the production database while the transactions are still taking place? (although i can select a time when transactions are fairly quiet through the 30 stations) Are there any hidden dangers i'm not seeing (not looking forward to needing to restore the DB if something goes wrong, restoring would take a lot of time with 10yrs of data).

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• How to get all captures of subgroup matches with preg_match_all()?

  - by hakre

  Update/Note: I think what I'm probably looking for is to get the captures of a group in PHP. Referenced: PCRE regular expressions using named pattern subroutines. (Read carefully:) I have a string that contains a variable number of segments (simplified): $subject = 'AA BB DD '; // could be 'AA BB DD CC EE ' as well I would like now to match the segments and return them via the matches array: $pattern = '/^(([a-z]+) )+$/i'; $result = preg_match_all($pattern, $subject, $matches); This will only return the last match for the capture group 2: DD. Is there a way that I can retrieve all subpattern captures (AA, BB, DD) with one regex execution? Isn't preg_match_all suitable for this? This question is a generalization. Both the $subject and $pattern are simplified. Naturally with such the general list of AA, BB, .. is much more easy to extract with other functions (e.g. explode) or with a variation of the $pattern. But I'm specifically asking how to return all of the subgroup matches with the preg_...-family of functions. For a real life case imagine you have multiple (nested) level of a variant amount of subpattern matches. Example This is an example in pseudo code to describe a bit of the background. Imagine the following: Regular definitions of tokens: CHARS := [a-z]+ PUNCT := [.,!?] WS := [ ] $subject get's tokenized based on these. The tokenization is stored inside an array of tokens (type, offset, ...). That array is then transformed into a string, containing one character per token: CHARS -> "c" PUNCT -> "p" WS -> "s" So that it's now possible to run regular expressions based on tokens (and not character classes etc.) on the token stream string index. E.g. regex: (cs)?cp to express one or more group of chars followed by a punctuation. As I now can express self-defined tokens as regex, the next step was to build the grammar. This is only an example, this is sort of ABNF style: words = word | (word space)+ word word = CHARS+ space = WS punctuation = PUNCT If I now compile the grammar for words into a (token) regex I would like to have naturally all subgroup matches of each word. words = (CHARS+) | ( (CHARS+) WS )+ (CHARS+) # words resolved to tokens words = (c+)|((c+)s)+c+ # words resolved to regex I could code until this point. Then I ran into the problem that the sub-group matches did only contain their last match. So I have the option to either create an automata for the grammar on my own (which I would like to prevent to keep the grammar expressions generic) or to somewhat make preg_match working for me somehow so I can spare that. That's basically all. Probably now it's understandable why I simplified the question. Related: pcrepattern man page Get repeated matches with preg_match_all()

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• iPhone - NSURLConnection does not receive data

  - by Jukurrpa

  Hi, I have a pretty weird problem with NSURLRequest. I'm using them to make an asynchronous image loading in an UITableView. The first time the tableView displays, all connections from NSURLRequests open correctly but receive absolutely no data, regardless of how long I wait. But as soon as I scroll down in the tableView, the newly created requests for the new cells work perfectly! The only way for the images on top of the tableView to load is to make them disappear by scrolling down and then up again, in order to create new requests. Here is what I do in "cellForRowAtIndexPath": UITableViewCell* cell = [tableView dequeueReusableCellWithIdentifier:@"Cell"]; if (cell == nil) { cell = [[UITableViewCell alloc] initWIthFrame:CGRectMake(0, 0, 300, 60)]; AsyncUIImageView imageView = [[AsynUIImageView alloc] initWithFrame:CGRectMake(0, 0, 60, 60)]; imageView.tag = IMG_VIEW // an enum for tags [cell addSubView:imageView]; [imageView release]; } AsyncUIImageView imageView = (AsyncUIImageView*)[cell viewWithTag:IMG_VIEW]; // I do a few cache checks here, but if the image aint cached I do this: [imageView loadImageFromURL:@"http://someurl.com/somepix.jpg"]; // all urls are different, just an example The AsyncUIImageView inherits from UIImageView and contains an NSURLConnection which opens upon calling the loadImageFromURL method: (void) loadImageFromURL:(NSString*)filename { if (self.connection != nil) [self.connection release]; if (self.data != nil) [self.data release]; NSURLRequest* request = [NSURLRequest requestWithURL:[[NSURL alloc] initWithString:fileName] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10.0]; self.connection = [[NSURLConnection alloc] initWithRequest:request delegate:self]; if (self.connection == nil) return; self.data = [[NSMutableData data] retain]; } I've created the delegate methods "connection: didReceiveData", which appends received data to self.data and "connectionDidFinishLoading" which sets the image and closes the connection once the transfer is complete. These work, but are never called for the first requests I create. I suspect this bug to come from the main thread not giving the first requests the control so they can execute themselves, as the same behavior happens if I keep my finger on the screen after a scroll: connections open themselves, but no data is received until I stop touching the screen. What am I doing wrong?

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• AudioTrack lag: obtainBuffer timed out

  - by BTR

  I'm playing WAVs on my Android phone by loading the file and feeding the bytes into AudioTrack.write() via the FileInputStream BufferedInputStream DataInputStream method. The audio plays fine and when it is, I can easily adjust sample rate, volume, etc on the fly with nice performance. However, it's taking about two full seconds for a track to start playing. I know AudioTrack has an inescapable delay, but this is ridiculous. Every time I play a track, I get this: 03-13 14:55:57.100: WARN/AudioTrack(3454): obtainBuffer timed out (is the CPU pegged?) 0x2e9348 user=00000960, server=00000000 03-13 14:55:57.340: WARN/AudioFlinger(72): write blocked for 233 msecs, 9 delayed writes, thread 0xba28 I've noticed that the delayed write count increases by one every time I play a track -- even across multiple sessions -- from the time the phone has been turned on. The block time is always 230 - 240ms, which makes sense considering a minimum buffer size of 9600 on this device (9600 / 44100). I've seen this message in countless searches on the Internet, but it usually seems to be related to not playing audio at all or skipping audio. In my case, it's just a delayed start. I'm running all my code in a high priority thread. Here's a truncated-yet-functional version of what I'm doing. This is the thread callback in my playback class. Again, this works (only playing 16-bit, 44.1kHz, stereo files right now), it just takes forever to start and has that obtainBuffer/delayed write message every time. public void run() { // Load file FileInputStream mFileInputStream; try { // mFile is instance of custom file class -- this is correct, // so don't sweat this line mFileInputStream = new FileInputStream(mFile.path()); } catch (FileNotFoundException e) {} BufferedInputStream mBufferedInputStream = new BufferedInputStream(mFileInputStream, mBufferLength); DataInputStream mDataInputStream = new DataInputStream(mBufferedInputStream); // Skip header try { if (mDataInputStream.available() > 44) mDataInputStream.skipBytes(44); } catch (IOException e) {} // Initialize device mAudioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, ConfigManager.SAMPLE_RATE, AudioFormat.CHANNEL_CONFIGURATION_STEREO, AudioFormat.ENCODING_PCM_16BIT, ConfigManager.AUDIO_BUFFER_LENGTH, AudioTrack.MODE_STREAM); mAudioTrack.play(); // Initialize buffer byte[] mByteArray = new byte[mBufferLength]; int mBytesToWrite = 0; int mBytesWritten = 0; // Loop to keep thread running while (mRun) { // This flag is turned on when the user presses "play" while (mPlaying) { try { // Check if data is available if (mDataInputStream.available() > 0) { // Read data from file and write to audio device mBytesToWrite = mDataInputStream.read(mByteArray, 0, mBufferLength); mBytesWritten += mAudioTrack.write(mByteArray, 0, mBytesToWrite); } } catch (IOException e) { } } } } If I can get past the artificially long lag, I can easily deal with the inherit latency by starting my write at a later, predictable position (ie, skip past the minimum buffer length when I start playing a file).

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• Calculating Growth-Rates by applying log-differences

  - by mropa

  I am trying to transform my data.frame by calculating the log-differences of each column and controlling for the rows id. So basically I like to calculate the growth rates for each id's variable. So here is a random df with an id column, a time period colum p and three variable columns: df <- data.frame (id = c("a","a","a","c","c","d","d","d","d","d"), p = c(1,2,3,1,2,1,2,3,4,5), var1 = rnorm(10, 5), var2 = rnorm(10, 5), var3 = rnorm(10, 5) ) df id p var1 var2 var3 1 a 1 5.375797 4.110324 5.773473 2 a 2 4.574700 6.541862 6.116153 3 a 3 3.029428 4.931924 5.631847 4 c 1 5.375855 4.181034 5.756510 5 c 2 5.067131 6.053009 6.746442 6 d 1 3.846438 4.515268 6.920389 7 d 2 4.910792 5.525340 4.625942 8 d 3 6.410238 5.138040 7.404533 9 d 4 4.637469 3.522542 3.661668 10 d 5 5.519138 4.599829 5.566892 Now I have written a function which does exactly what I want BUT I had to take a detour which is possibly unnecessary and can be removed. However, somehow I am not able to locate the shortcut. Here is the function and the output for the posted data frame: fct.logDiff <- function (df) { df.log <- dlply (df, "code", function(x) data.frame (p = x$p, log(x[, -c(1,2)]))) list.nalog <- llply (df.log, function(x) data.frame (p = x$p, rbind(NA, sapply(x[,-1], diff)))) ldply (list.nalog, data.frame) } fct.logDiff(df) id p var1 var2 var3 1 a 1 NA NA NA 2 a 2 -0.16136569 0.46472004 0.05765945 3 a 3 -0.41216720 -0.28249264 -0.08249587 4 c 1 NA NA NA 5 c 2 -0.05914281 0.36999681 0.15868378 6 d 1 NA NA NA 7 d 2 0.24428771 0.20188025 -0.40279188 8 d 3 0.26646102 -0.07267311 0.47041227 9 d 4 -0.32372771 -0.37748866 -0.70417351 10 d 5 0.17405309 0.26683625 0.41891802 The trouble is due to the added NA-rows. I don't want to collapse the frame and reduce it, which would be automatically done by the diff() function. So I had 10 rows in my original frame and am keeping the same amount of rows after the transformation. In order to keep the same length I had to add some NAs. I have taken a detour by transforming the data.frame into a list, add the NAs, and afterwards transform the list back into a data.frame. That looks tedious. Any ideas to avoid the data.frame-list-data.frame class transformation and optimize the function?

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