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  • OSX / Kernel extensions: problem locating a driver (that extends IOSCSIPeripheralDeviceType00)

    - by LG
    Hi, I'm implementing a driver that extends IOSCSIPeripheralDeviceType00 as I need to send custom SCSI commands to a device. I'm following the VendorSpecificType00 and SimpleUserClient examples and http://wagerlabs.com/writing-a-mac-osx-usb-device-driver-that-impl as an example. I built my kernel extension and it loads fine with kextload and it shows up in kextstat. The problem is that I can't locate it in my user space code. Here's the important (I think) part of: my driver code: #define super IOSCSIPeripheralDeviceType00 OSDefineMetaClassAndStructors(com_mycompany_driver_Foo, IOSCSIPeripheralDeviceType00) my user client code: #define super IOUserClient OSDefineMetaClassAndStructors(com_mycompany_driver_FooUserClient, IOUserClient) the plist: CFBundleIdentifier -> com.mycompany.driver.Foo IOCLass -> com_mycompany_driver_Foo IOUserClientClass -> com_mycompany_driver_FooUserClient IOProviderClass -> IOSCSIPeripheralDeviceNub Here's how I try to locate the driver in my user space code (similar to SimpleUserClient): dictRef = IOServiceMatching("com_mycompany_driver_Foo"); kernResult = IOServiceGetMatchingServices(kIOMasterPortDefault, dictRef, &iterator); When I execute the code, iterator is 0. I noticed that in the VendorSpecificType00 code, the localization of the driver is done differently: dictRef = IOServiceMatching("IOBlockStorageServices"); kr = IOServiceGetMatchingServices(kIOMasterPortDefault, dictRef, &iter); while ((service = IOIteratorNext(iter))) { io_registry_entry_t parent; kr = IORegistryEntryGetParentEntry(service, kIOServicePlane, &parent); ... // We're only interested in the parent object if it's our driver class. if (IOObjectConformsTo(parent, "com_apple_dts_driver_VendorSpecificType00")) { I tried doing that but it didn't work either. Thanks for reading and your help, -L

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  • Banning by IP with php/mysql

    - by incrediman
    I want to be able to ban users by IP. My idea is to keep a list of IP's as rows in an BannedIPs table (the IP column would be an index). To check users' IP's against the table, I will keep a session variable called $_SESSION['IP'] for each session. If on any request, $_SESSION['IP'] doesn't match $_SERVER['REMOTE_ADDR'], I will update $_SESSION['IP'] and check the BannedIPs table to see if the IP is banned. (A flag will also be saved as a session variable specifying whether or not the user is banned) Here are the things I'm wondering: Does that sound like a good strategy with regards to speed and security (would someone be able to get around the IP ban somehow, other than changing IP's)? What's the best way to structure a mysql query that checks to see if a row exists? That is, what's the best way to query the db to see if a row with a certain IP exists (to check if it's banned)? Should I save the IP's as integers or strings? Note that... I estimate there will be between 1,000-10,000 banned IP's stored in the database. $_SERVER['REMOTE_ADDR'] is the IP from which the current request was sent.

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  • Serialization Performance and Google Android

    - by Jomanscool2
    I'm looking for advice to speed up serialization performance, specifically when using the Google Android. For a project I am working on, I am trying to relay a couple hundred objects from a server to the Android app, and am going through various stages to get the performance I need. First I tried a terrible XML parser that I hacked together using Scanner specifically for this project, and that caused unbelievably slow performance when loading the objects (~5 minutes for a 300KB file). I then moved away from that and made my classes implement Serializable and wrote the ArrayList of objects I had to a file. Reading that file into the objects the Android, with the file already downloaded mind you, was taking ~15-30 seconds for the ~100KB serialized file. I still find this completely unacceptable for an Android app, as my app requires loading the data when starting the application. I have read briefly about Externalizable and how it can increase performance, but I am not sure as to how one implements it with nested classes. Right now, I am trying to store an ArrayList of the following class, with the nested classes below it. public class MealMenu implements Serializable{ private String commonsName; private long startMillis, endMillis, modMillis; private ArrayList<Venue> venues; private String mealName; } And the Venue class: public class Venue implements Serializable{ private String name; private ArrayList<FoodItem> foodItems; } And the FoodItem class: public class FoodItem implements Serializable{ private String name; private boolean vegan; private boolean vegetarian; } IF Externalizable is the way to go to increase performance, is there any information as to how java calls the methods in the objects when you try to write it out? I am not sure if I need to implement it in the parent class, nor how I would go about serializing the nested objects within each object.

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  • Which persistent & lightweight queue messaging for cross domain (> 2) data exchange with rails integ

    - by Erwan
    Hi all, I'm looking for the right messaging system for my needs. Can you help me ? For now, there won't be a huge amount of data to process, but I don't want to be limited later ... The machines are not just web servers, so the messaging tool should be lightweight, even if processing is not very speed. When some data change on a server, all servers should have the information and process it locally. (should I create one channel per server on each of them ?) The frontend is written on Rails, so it is important, in order to simplify the development, that there is a gem / plugin to manage communications and data sent. At this time : RabbitMQ + workling seems to fit my needs. Could this be a right choice ? ActiveMQ make me afraid, because of Java (I really don't know very well Java, but it seems to me to be big CPU consumer) Others don't seem to be as mature as them. There might be lot of development using this kind of technology, so I can't go to the wrong way ! Thank you for help.

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  • count on LINQ union

    - by brechtvhb
    I'm having this link statement: List<UserGroup> domains = UserRepository.Instance.UserIsAdminOf(currentUser.User_ID); query = (from doc in _db.Repository<Document>() join uug in _db.Repository<User_UserGroup>() on doc.DocumentFrom equals uug.User_ID where domains.Contains(uug.UserGroup) select doc) .Union(from doc in _db.Repository<Document>() join uug in _db.Repository<User_UserGroup>() on doc.DocumentTo equals uug.User_ID where domains.Contains(uug.UserGroup) select doc); Running this statement doesn't cause any problems. But when I want to count the resultset the query suddenly runs quite slow. totalRecords = query.Count(); The result of this query is : SELECT COUNT([t5].[DocumentID]) FROM ( SELECT [t4].[DocumentID], [t4].[DocumentFrom], [t4].[DocumentTo] FROM ( SELECT [t0].[DocumentID], [t0].[DocumentFrom], [t0].[DocumentTo FROM [dbo].[Document] AS [t0] INNER JOIN [dbo].[User_UserGroup] AS [t1] ON [t0].[DocumentFrom] = [t1].[User_ID] WHERE ([t1].[UserGroupID] = 2) OR ([t1].[UserGroupID] = 3) OR ([t1].[UserGroupID] = 6) UNION SELECT [t2].[DocumentID], [t2].[DocumentFrom], [t2].[DocumentTo] FROM [dbo].[Document] AS [t2] INNER JOIN [dbo].[User_UserGroup] AS [t3] ON [t2].[DocumentTo] = [t3].[User_ID] WHERE ([t3].[UserGroupID] = 2) OR ([t3].[UserGroupID] = 3) OR ([t3].[UserGroupID] = 6) ) AS [t4] ) AS [t5] Can anyone help me to improve the speed of the count query? Thanks in advance!

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  • WF performance with new 20,000 persisted workflow instances each month

    - by Nikola Stjelja
    Windows Workflow Foundation has a problem that is slow when doing WF instances persistace. I'm planning to do a project whose bussiness layer will be based on WF exposed WCF services. The project will have 20,000 new workflow instances created each month, each instance could take up to 2 months to finish. What I was lead to belive that given WF slownes when doing peristance my given problem would be unattainable given performance reasons. I have the following questions: Is this true? Will my performance be crap with that load(given WF persitance speed limitations) How can I solve the problem? We currently have two possible solutions: 1. Each new buisiness process request(e.g. Give me a new drivers license) will be a new WF instance, and the number of persistance operations will be limited by forwarding all status request operations to saved state values in a separate database. 2. Have only a small amount of Workflow Instances up at any give time, without any persistance ofso ever(only in case of system crashes etc.), by breaking each workflow stap in to a separate worklof and that workflow handling each business process request instance in the system that is at that current step(e.g. I'm submitting my driver license reques form, which is step one... we have 100 cases of that, and my step one workflow will handle every case simultaneusly). I'm very insterested in solution for that problem. If you want to discuss that problem pleas be free to mail me at [email protected]

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  • JQuery Cycle fails on Page Refresh

    - by Darknight
    In a similar issue as this one: http://stackoverflow.com/questions/1719475/jquery-cycle-firefox-squishing-images I've managed to overcome the initial problem using Jeffs answer in the above link. However now I have noticed a new bug, upon page refresh it simply does not work. I have tried a hard refresh (ctrl+F5) but this does not work. However when you come page to the page it loads fine. here is my modified version (taken from Jeff's): <script type="text/javascript"> $(document).ready(function() { var imagesRemaining = $('#slideshow img').length; $('#slideshow img').bind('load', function(e) { imagesRemaining = imagesRemaining - 1; if (imagesRemaining == 0) { $('#slideshow').show(); $('#slideshow').cycle({ fx: 'shuffle', speed: 1200 }); } }); }); </script> Any ideas? I've also tried JQuery Live but could not implement it correctly. I've also tried Meta tags to force images to load. But it only works first time round.

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  • Is it practical to program with your feet?

    - by bmm
    Has anyone tried using foot pedals in addition to the traditional keyboard and mouse combo to improve your effectiveness in the editor? Any actual experiences out there? Does it work, or is it just for carpal tunnel relief? I found one blog entry from a programmer who actually tried it: So now I can type using my feet for most of the modifier keys. I am using the pedals as I type this. I am still getting used to them, but the burning in my left wrist has definitely reduced. I think I can also type a little faster, but I am too lazy to do the speed tests with and without the pedals to verify this. On the negative side: Working out where to put your feet when you aren’t typing can be a little awkward. The pedals tend to move around the carpet, despite being metal and quite heavy. Some small spikes might have helped. Although the travel on the pedals is small, they are surprisingly stiff. Another programmer's experience: Anybody with hand pain must get foot pedals, since they can remove a tremendous load from your hands. I have two foot pedals, and use one for the SHIFT key, and the other for the CONTROL key. (I still type META by hand.) I have found that in the process of using the Emacs text editor to compose computer programs, I tend to use the SHIFT, CONTROL and META keys constantly, and it is easy to remove most of this load from one's hands. Some foot switch products: Savant Elite Triple Foot Switch FragPedal Bilbo Step On It!

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  • Why is the Clojure Hello World program so slow compared to Java and Python?

    - by viksit
    Hi all, I'm reading "Programming Clojure" and I was comparing some languages I use for some simple code. I noticed that the clojure implementations were the slowest in each case. For instance, Python - hello.py def hello_world(name): print "Hello, %s" % name hello_world("world") and result, $ time python hello.py Hello, world real 0m0.027s user 0m0.013s sys 0m0.014s Java - hello.java import java.io.*; public class hello { public static void hello_world(String name) { System.out.println("Hello, " + name); } public static void main(String[] args) { hello_world("world"); } } and result, $ time java hello Hello, world real 0m0.324s user 0m0.296s sys 0m0.065s and finally, Clojure - hellofun.clj (defn hello-world [username] (println (format "Hello, %s" username))) (hello-world "world") and results, $ time clj hellofun.clj Hello, world real 0m1.418s user 0m1.649s sys 0m0.154s Thats a whole, garangutan 1.4 seconds! Does anyone have pointers on what the cause of this could be? Is Clojure really that slow, or are there JVM tricks et al that need to be used in order to speed up execution? More importantly - isn't this huge difference in performance going to be an issue at some point? (I mean, lets say I was using Clojure for a production system - the gain I get in using lisp seems completely offset by the performance issues I can see here). The machine used here is a 2007 Macbook Pro running Snow Leopard, a 2.16Ghz Intel C2D and 2G DDR2 SDRAM. BTW, the clj script I'm using is from here and looks like, #!/bin/bash JAVA=/System/Library/Frameworks/JavaVM.framework/Versions/1.6/Home/bin/java CLJ_DIR=/opt/jars CLOJURE=$CLJ_DIR/clojure.jar CONTRIB=$CLJ_DIR/clojure-contrib.jar JLINE=$CLJ_DIR/jline-0.9.94.jar CP=$PWD:$CLOJURE:$JLINE:$CONTRIB # Add extra jars as specified by `.clojure` file if [ -f .clojure ] then CP=$CP:`cat .clojure` fi if [ -z "$1" ]; then $JAVA -server -cp $CP \ jline.ConsoleRunner clojure.lang.Repl else scriptname=$1 $JAVA -server -cp $CP clojure.main $scriptname -- $* fi

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  • Can a GeneralPath be modified?

    - by Dov
    java2d is fairly expressive, but requires constructing lots of objects. In contrast, the older API would let you call methods to draw various shapes, but lacks all the new features like transparency, stroke, etc. Java has fairly high costs associated with object creation. For speed, I would like to create a GeneralPath whose structure does not change, but go in and change the x,y points inside. path = new GeneralPath(GeneralPath.WIND_EVEN_ODD, 10); path.moveTo(x,y); path.lineTo(x2, y2); double len = Math.sqrt((x2-x)*(x2-x) + (y2-y)*(y2-y)); double dx = (x-x2) * headLen / len; double dy = (y-y2) * headLen / len; double dx2 = -dy * (headWidth/headLen); double dy2 = dx * (headWidth/headLen); path.lineTo(x2 + dx + dx2, y2 + dy + dy2); path.moveTo(x2 + dx - dx2, y2 + dy - dy2); path.lineTo(x2,y2); This one isn't even that long. Imagine a much longer sequence of commands, and only the ones on the end are changing. I just want to be able to overwrite commands, to have an iterator effectively. Does that exist?

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  • Trouble with an depreciated constrictor visual basic visual studio 2010

    - by VBPRIML
    My goal is to print labels with barcodes and a date stamp from an entry to a zebra TLP 2844 when the user clicks the ok button/hits enter. i found what i think might be the code for this from zebras site and have been integrating it into my program but part of it is depreciated and i cant quite figure out how to update it. below is what i have so far. The printer is attached via USB and the program will also store the entered numbers in a database but i have that part done. any help would be greatly Appreciated.   Public Class ScanForm      Inherits System.Windows.Forms.Form    Public Const GENERIC_WRITE = &H40000000    Public Const OPEN_EXISTING = 3    Public Const FILE_SHARE_WRITE = &H2      Dim LPTPORT As String    Dim hPort As Integer      Public Declare Function CreateFile Lib "kernel32" Alias "CreateFileA" (ByVal lpFileName As String,                                                                           ByVal dwDesiredAccess As Integer,                                                                           ByVal dwShareMode As Integer, <MarshalAs(UnmanagedType.Struct)> ByRef lpSecurityAttributes As SECURITY_ATTRIBUTES,                                                                           ByVal dwCreationDisposition As Integer, ByVal dwFlagsAndAttributes As Integer,                                                                           ByVal hTemplateFile As Integer) As Integer          Public Declare Function CloseHandle Lib "kernel32" Alias "CloseHandle" (ByVal hObject As Integer) As Integer      Dim retval As Integer           <StructLayout(LayoutKind.Sequential)> Public Structure SECURITY_ATTRIBUTES          Private nLength As Integer        Private lpSecurityDescriptor As Integer        Private bInheritHandle As Integer      End Structure            Private Sub OKButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles OKButton.Click          Dim TrNum        Dim TrDate        Dim SA As SECURITY_ATTRIBUTES        Dim outFile As FileStream, hPortP As IntPtr          LPTPORT = "USB001"        TrNum = Me.ScannedBarcodeText.Text()        TrDate = Now()          hPort = CreateFile(LPTPORT, GENERIC_WRITE, FILE_SHARE_WRITE, SA, OPEN_EXISTING, 0, 0)          hPortP = New IntPtr(hPort) 'convert Integer to IntPtr          outFile = New FileStream(hPortP, FileAccess.Write) 'Create FileStream using Handle        Dim fileWriter As New StreamWriter(outFile)          fileWriter.WriteLine(" ")        fileWriter.WriteLine("N")        fileWriter.Write("A50,50,0,4,1,1,N,")        fileWriter.Write(Chr(34))        fileWriter.Write(TrNum) 'prints the tracking number variable        fileWriter.Write(Chr(34))        fileWriter.Write(Chr(13))        fileWriter.Write(Chr(10))        fileWriter.Write("A50,100,0,4,1,1,N,")        fileWriter.Write(Chr(34))        fileWriter.Write(TrDate) 'prints the date variable        fileWriter.Write(Chr(34))        fileWriter.Write(Chr(13))        fileWriter.Write(Chr(10))        fileWriter.WriteLine("P1")        fileWriter.Flush()        fileWriter.Close()        outFile.Close()        retval = CloseHandle(hPort)          'Add entry to database        Using connection As New SqlClient.SqlConnection("Data Source=MNGD-LABS-APP02;Initial Catalog=ScannedDB;Integrated Security=True;Pooling=False;Encrypt=False"), _        cmd As New SqlClient.SqlCommand("INSERT INTO [ScannedDBTable] (TrackingNumber, Date) VALUES (@TrackingNumber, @Date)", connection)            cmd.Parameters.Add("@TrackingNumber", SqlDbType.VarChar, 50).Value = TrNum            cmd.Parameters.Add("@Date", SqlDbType.DateTime, 8).Value = TrDate            connection.Open()            cmd.ExecuteNonQuery()            connection.Close()        End Using          'Prepare data for next entry        ScannedBarcodeText.Clear()        Me.ScannedBarcodeText.Focus()      End Sub

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  • web browser become slow or no response after several ajax calls

    - by Patrick
    I'm totally newbie to jquery and ajax, my recently project is to help the representatives (reps) to manage customer quotations online. I have a page which displays all the quotations in a big table. I've managed to use ajax to fetch and display the quotations which associate to a particular rep after i click that rep's name. But the only problem is the speed of response. The first few clicks are ok and very smooth. But after several tries, the response become slow and I cant even scroll down the webpage, and later on the web browser craches.... Please have a look at my ajax code. here it is: <!-- AJAX FETCH QUOTES DATA + Tablesorter + FIXED TABLE HEADER--> <script type="text/javascript"> //<![CDATA[ $(function(){ $("a.repID").click(function(){ $('div#loader').append("<p align='center'><img src='images/loadingbar2.gif' id='loading' /></p>"); var repID = $(this).attr("title"); $.ajax({ type:'POST', url:'quote_info.php', data:'repID=' + repID, cache: false, success:function(data) { $("#container").html('<div id="content">' + data + '</div>'); $("#loading").fadeOut(500, function() {$(this).remove();}); $("#sortme").tablesorter(); $('.tbl').fixedtableheader(); } }); return false; }); }); </script> <!-- AJAX FETCH QUOTES DATA + Tablesorter + FIXED TABLE HEADER-->

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  • What is the correct way to create dynamic javascript in ASP.net MVC2?

    - by sabbour
    I'm creating a Google Maps partial view/user control in my project that is passed a strongly typed list of objects containing latitude and longitude values. Currently, this is the code I have for the partial: <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<IEnumerable<Project.Models.Entities.Location>>" %> <!-- Place for google to put the map --> <div id="report_map_canvas" style="width: 100%; height: 728px; margin-bottom: 2px;"> </div> <script type='text/javascript'> google.load("maps", "2"); $(document).ready(initializeMap); function initializeMap() { if (GBrowserIsCompatible()) { var map = new GMap2(document.getElementById('report_map_canvas')); map.setCenter(new GLatLng(51.5, -0.1167), 2); <% foreach (var item in Model) { %> map.addOverlay(new GMarker(new GLatLng('<%= Html.Encode(item.latitude)%>','<%= Html.Encode(item.longitude)%>'),{ title: '<%= Html.Encode(String.Format("{0:F}",item.speed)) %> km/h '})); <% } %> map.setUIToDefault(); } } </script> Is it right to dynamically create the javascript file this way by looping over the list and emitting javascript? Is there a better way to do it?

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  • Direct invocation vs indirect invocation in C

    - by Mohit Deshpande
    I am new to C and I was reading about how pointers "point" to the address of another variable. So I have tried indirect invocation and direct invocation and received the same results (as any C/C++ developer could have predicted). This is what I did: int cost; int *cost_ptr; int main() { cost_ptr = &cost; //assign pointer to cost cost = 100; //intialize cost with a value printf("\nDirect Access: %d", cost); cost = 0; //reset the value *cost_ptr = 100; printf("\nIndirect Access: %d", *cost_ptr); //some code here return 0; //1 } So I am wondering if indirect invocation with pointers has any advantages over direct invocation or vice-versa. Some advantages/disadvantages could include speed, amount of memory consumed performing the operation (most likely the same but I just wanted to put that out there), safeness (like dangling pointers) , good programming practice, etc. 1Funny thing, I am using the GNU C Compiler (gcc) and it still compiles without the return statement and everything is as expected. Maybe because the C++ compiler will automatically insert the return statement if you forget.

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  • How does one target all divs of any webpage but differentiate them in javascript?

    - by Chaz
    So I am trying to create an extension in Chrome (a prototype for a project that I am doing) that targets all of the <div> tags of any web page, hides them or rather doesn't display them until the user clicks the mouse (further explained below). So typing a url into the browser yields a white page. The person clicks, and the first <div> appears (probably the mast head or menu). The user clicks again and the second <div> appears. I have gotten to the point where I can hide or show all <div>'s (the obvious easy part) but I am not sure how to go about targeting each since every website has different id's for them while still using the <div> tag. This is what I need the most help with. This is part of a grander operation called the Web Crank. It's just a physical crank that controls the speed by which a web page loads. Each time you make one full rotation of the crank, one section (the first <div>) of the web page loads. The faster you go, the quicker the page loads. I hope this is clear enough. I am a newbie when it comes to this, but I have done some minor coding in the past and it's not such a big deal. Thanks for your help!

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  • Temporary debug releases and final application releases

    - by baron
    I have a quick question regarding debug and release in VS 2008. I have an app i've been working on - its not yet complete but the bulk of the functionality is there. So basically i'm trying to give a copy of it now to the person helping with documentation - just so they can have a play and get the feel for what i've made. Now the question is how to provide it to them. I was told to just copy the .exe out of the debug/bin folder and put that onto USB. But when testing, if I run this .exe anywhere else (outside of this folder) it crashes. I've now worked out why this is: var path = ConfigurationManager.AppSettings["PathToUse"]; var files = Directory.GetFiles(path); throws a null reference, so that App.config file is not being used. If I copy that file in with the .exe it works again. So actually my question is regarding the best way to manage this situation. What is the best way to provide a working copy to people, and, is there a reference on preparing apps for release - so everything is packaged together and installed in a clean structured folder heirarchy?

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  • Fast JSON serialization (and comparison with Pickle) for cluster computing in Python?

    - by user248237
    I have a set of data points, each described by a dictionary. The processing of each data point is independent and I submit each one as a separate job to a cluster. Each data point has a unique name, and my cluster submission wrapper simply calls a script that takes a data point's name and a file describing all the data points. That script then accesses the data point from the file and performs the computation. Since each job has to load the set of all points only to retrieve the point to be run, I wanted to optimize this step by serializing the file describing the set of points into an easily retrievable format. I tried using JSONpickle, using the following method, to serialize a dictionary describing all the data points to file: def json_serialize(obj, filename, use_jsonpickle=True): f = open(filename, 'w') if use_jsonpickle: import jsonpickle json_obj = jsonpickle.encode(obj) f.write(json_obj) else: simplejson.dump(obj, f, indent=1) f.close() The dictionary contains very simple objects (lists, strings, floats, etc.) and has a total of 54,000 keys. The json file is ~20 Megabytes in size. It takes ~20 seconds to load this file into memory, which seems very slow to me. I switched to using pickle with the same exact object, and found that it generates a file that's about 7.8 megabytes in size, and can be loaded in ~1-2 seconds. This is a significant improvement, but it still seems like loading of a small object (less than 100,000 entries) should be faster. Aside from that, pickle is not human readable, which was the big advantage of JSON for me. Is there a way to use JSON to get similar or better speed ups? If not, do you have other ideas on structuring this? (Is the right solution to simply "slice" the file describing each event into a separate file and pass that on to the script that runs a data point in a cluster job? It seems like that could lead to a proliferation of files). thanks.

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  • How is it that json serialization is so much faster than yaml serialization in python?

    - by guidoism
    I have code that relies heavily on yaml for cross-language serialization and while working on speeding some stuff up I noticed that yaml was insanely slow compared to other serialization methods (e.g., pickle, json). So what really blows my mind is that json is so much faster that yaml when the output is nearly identical. >>> import yaml, cjson; d={'foo': {'bar': 1}} >>> yaml.dump(d, Dumper=yaml.SafeDumper) 'foo: {bar: 1}\n' >>> cjson.encode(d) '{"foo": {"bar": 1}}' >>> import yaml, cjson; >>> timeit("yaml.dump(d, Dumper=yaml.SafeDumper)", setup="import yaml; d={'foo': {'bar': 1}}", number=10000) 44.506911039352417 >>> timeit("yaml.dump(d, Dumper=yaml.CSafeDumper)", setup="import yaml; d={'foo': {'bar': 1}}", number=10000) 16.852826118469238 >>> timeit("cjson.encode(d)", setup="import cjson; d={'foo': {'bar': 1}}", number=10000) 0.073784112930297852 PyYaml's CSafeDumper and cjson are both written in C so it's not like this is a C vs Python speed issue. I've even added some random data to it to see if cjson is doing any caching, but it's still way faster than PyYaml. I realize that yaml is a superset of json, but how could the yaml serializer be 2 orders of magnitude slower with such simple input?

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  • What algorithms are suitable for this simple machine learning problem?

    - by user213060
    I have a what I think is a simple machine learning question. Here is the basic problem: I am repeatedly given a new object and a list of descriptions about the object. For example: new_object: 'bob' new_object_descriptions: ['tall','old','funny']. I then have to use some kind of machine learning to find previously handled objects that had similar descriptions, for example, past_similar_objects: ['frank','steve','joe']. Next, I have an algorithm that can directly measure whether these objects are indeed similar to bob, for example, correct_objects: ['steve','joe']. The classifier is then given this feedback training of successful matches. Then this loop repeats with a new object. a Here's the pseudo-code: Classifier=new_classifier() while True: new_object,new_object_descriptions = get_new_object_and_descriptions() past_similar_objects = Classifier.classify(new_object,new_object_descriptions) correct_objects = calc_successful_matches(new_object,past_similar_objects) Classifier.train_successful_matches(object,correct_objects) But, there are some stipulations that may limit what classifier can be used: There will be millions of objects put into this classifier so classification and training needs to scale well to millions of object types and still be fast. I believe this disqualifies something like a spam classifier that is optimal for just two types: spam or not spam. (Update: I could probably narrow this to thousands of objects instead of millions, if that is a problem.) Again, I prefer speed when millions of objects are being classified, over accuracy. What are decent, fast machine learning algorithms for this purpose?

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  • Embedded Vimeo Video Callbacks

    - by Andrew
    This post is kind of a follow up to a post I made earlier in regards to HTML5 video callbacks. In that thread, I was given a great piece of code that would allow for the browser to be informed of when the video stops playing and then fire off an action (with jQuery). This is the code I'm currently using: $('video.normal').bind('ended', function(){ $(this).fadeOut().queue(function(){ $(this).siblings('.post-video').fadeIn(); $(this).dequeue(); }); }); Which basically fades the video out when it's completed and brings a poster frame of the video (or similar image) back into view. Well, the scope of the project has changed and now the client is asking for true full screen video and different size videos to be delivered based on user connection speed, something that's a little over my head and a lot over budget. So I've been researching and a Vimeo Plus player seems like a great alternative for visitors using a desktop browser (HD embeds, true full screen, and more). Thing is, I need that above code to continue working in some capacity or another, so does the embedded Vimeo player offer a similar callback that I can utilize? Or am I SOL here? Thanks in advance!

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  • Algorithm to determine which points should be visible on a map based on zoom

    - by lgratian
    Hi! I'm making a Google Maps-like application for a course at my Uni (not something complex, it should load the map of a city for example, not the whole world). The map can have many layers, including markers (restaurants, hospitals, etc.) The problem is that when you have many points and you zoom out the map it doesn't look right. At this zoom level only some points need to be visible (and at the maximum map size, all points). The question is: how can you determine which points should be visible for a specified zoom level? Because I have implemented a PR Quadtree to speed up rendering I thought that I could define some "high-priority" markers (that are always visible, defined in the map editor) and put them in a queue. At each step a marker is removed from the queue and all it's neighbors that are at least D units away (D depends on the zoom levels) are chosen and inserted in the queue, and so on. Is there any better way than the algorithm I thought of? Thanks in advance!

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  • How to preload images using jquery for carousel?

    - by Pandiya Chendur
    I used jquery stepcarousel plugin and it works fine... But how to preload images that is used by the plugin... I am using this, <div id="mygallery" class="stepcarousel"> <div class="belt"> <div class="panel"> <img src="Images/img1.jpg" /> </div> <div class="panel"> <img src="Images/img2.jpg" /> </div> </div> </div> <script type="text/javascript"> stepcarousel.setup({ galleryid: 'mygallery', //id of carousel DIV beltclass: 'belt', //class of inner "belt" DIV containing all the panel DIVs panelclass: 'panel', //class of panel DIVs each holding content autostep: { enable: true, moveby: 1, pause: 3000 }, panelbehavior: { speed: 500, wraparound: false, persist: true }, defaultbuttons: { enable: true, moveby: 1, leftnav: ['Images/lft_arrow.jpg', -5, 220], rightnav: ['Images/rit_arrow.jpg', -5, 220] }, statusvars: ['statusA', 'statusB', 'statusC'], //register 3 variables that contain current panel (start), current panel (last), and total panels contenttype: ['inline'] //content setting ['inline'] or ['ajax', 'path_to_external_file'] }) </script> How to preload images used by mygallery div such that i can avoid flickering.....

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  • (solved) jQuery click and drag/scroll window: jagged movement

    - by Josh
    Edit: derp, using pageX/Y instead of clientX/Y -- apparently scrollBy expects input with that offset rather than the other. Jaggy movement gone. I am getting jagged movement when doing small scroll increments using the following bindings. Can anyone point me in the right direction for how to smooth this out? FYI, its intermittent. It seems like, if I click and hold for a second, then drag at a decent speed there are no problems. Edit: What the hell? I get this output on debug... obvious jog backwards and forwards. This will happen in succession and seems to have no correlation with the mouse, other than the mouse is moving. x 398 : 403 y 374 : 377 x 403 : 399 y 377 : 374 x 399 : 404 y 374 : 377 Josh sococo.client.panMap = function(e){ e.preventDefault(); var movex = sococo.client.currX - e.pageX ; var movey = sococo.client.currY - e.pageY; console.log( sococo.client.currX +" : " + e.pageX ); window.scrollBy(movex,movey); sococo.client.currY = e.pageY; sococo.client.currX = e.pageX; } $(document).mousedown( function(e){ e.preventDefault(); sococo.client.currX = e.pageX; sococo.client.currY = e.pageY; $(document).bind( "mousemove", sococo.client.panMap ); }); $(document).mouseup( function(e){ e.preventDefault(); $(document).unbind( "mousemove", sococo.client.panMap ); });

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  • Advice on improving programming skills, learning capabilities?

    - by anonymous-coward1234
    Hi all, After 2,5 years of professional Java programing, I still have problems that make my job difficult and, more importantly - more times that I would like to admit - not enjoyable. I would like to ask for advice by more experienced people on ways that would help me overcome them. These are the problems I have: I do not absorb new knowledge easily. Even when I understand something, after a couple of days I easily forget even basic stuff. Other co-workers, even with the same working experience, when reading new technologies put things easily into "context", and are able to compare in "real time| similar technologies they already have used. I always try to address all the issues to whatever I am doing at one go, which results in me trying to resolve too many problems at the same time, losing completely control. I find it difficult to make my mind on a single problem that I should address first, and even when I do, and find myself throwing away code that I wrote because I started addressing the wrong issue first. As far as architecture and data modeling is concerned, I have difficulty making decisions on what objects must be created, with what hierarchy, interfaces, abstraction etc. I imagine that - to a certain degree - these things come with experience. But after 2,5 years of Java programming, I would expect myself to have come much farther that I have come, both in terms of absorption and experience. Is there a way to improve my learning speed? Any books, methods, advice is welcome.

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  • faster way to draw an image

    - by iHorse
    im trying to combine two images into a single image. unfortunately this has to be done very quickly in response to a user sliding a UISlider. i can combine the two images into a single image no problem. but the way I'm doing it is horribly slow. the sliders stick and jump rather frustratingly. i don't think i can throw the code into a background thread because i would run out of threads to quickly. i haven't actually tired that yet. below is my code. any ideas on how to speed it up would be helpful. UIGraphicsBeginImageContext(CGSizeMake(bodyImage.theImage.image.size.width * 1.2, bodyImage.theImage.image.size.height * 1.2)); [bodyImage.theImage.image drawInRect: CGRectMake(-2 + ((bodyImage.theImage.image.size.width * 1.2) - bodyImage.theImage.image.size.width)/2, kHeadAdjust, bodyImage.theImage.image.size.width * bodyImage.currentScale, bodyImage.theImage.image.size.height * bodyImage.currentScale)]; if(isCustHead) { [Head.theImage.image drawInRect: CGRectMake((bodyImage.theImage.image.size.width * 1.2 - headWidth)/2 - 11, 0, headWidth * 0.92, headWidth * (Head.theImage.image.size.height/Head.theImage.image.size.width) * 0.92)]; } else { [Head.theImage.image drawInRect: CGRectMake((bodyImage.theImage.image.size.width * 1.2 - (headWidth * defaultHeadAdjust))/2 - 10, 0, (headWidth * defaultHeadAdjust * 0.92), (headWidth * defaultHeadAdjust) * (Head.theImage.image.size.height/Head.theImage.image.size.width) * 0.92)]; } drawSurface.theImage.image = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext();

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