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• CSV parser in C++

  - by User1

  All I need is a good CSV file parser for C++. At this point it can really just be a comma-delimited parser (ie don't worry about escaping new lines and commas). The main need is a line-by-line parser that will return a vector for the next line each time the method is called. I found this article which looks quite promising: http://www.boost.org/doc/libs/1_35_0/libs/spirit/example/fundamental/list_parser.cpp I've never used Boost's Spirit, but am willing to try it. Is it overkill/bloated or is it fast and efficient? Does anyone have faster algorithms using STL or anything else? Thanks!

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• How can I efficiently retrieve a large number of database settings as PHP variables?

  - by Steven

  Currently all of my script's settings are located in a PHP file which I 'include'. I'm in the process of moving these settings (about 100) to a database table called 'settings'. However I'm struggling to find an efficient way of retrieving all of them into the file. The settings table has 3 columns: ID (autoincrements) name value Two example rows might be: 1 admin_user john 2 admin_email_address [email protected] The only way I can think of retrieving each setting is like this: $result = mysql_query("SELECT value FROM settings WHERE name = 'admin_user'"); $row = mysql_fetch_array($result); $admin_user = $row['value']; $result = mysql_query("SELECT value FROM settings WHERE name = 'admin_email_address'"); $row = mysql_fetch_array($result); $admin_email_address = $row['value']; etc etc Doing it this way will take up a lot of code and will likely be slow. Is there a better way? Thanks.

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• JS Framework that doesn't use CSS selectors?

  - by RoToRa

  A thing that I noticed about most JavaScript frameworks is that the most common way to find/access the DOM elements is to use CSS selectors. However this usually requires the framework to include a CSS selector parser, because they need to support selectors, that the browser natively doesn't, foremost the frameworks own proprietary extensions. I would think that these parsers are large and slow. Wouldn't it be more efficient to have something that doesn't require a parser, such a chained method calls? Some like: id("example").children().class("test").hasAttribute("href") instead of $("#example > .test[href]") Are there any frameworks around that do something like this? And how do they compare with jQuery and friends in regard to performance and size? EDIT: You can consider this a theoretical discussion topic. I don't plan to use anything other than jQuery in any practical projects in near furure. I was just wondering why there aren't any other, possibly better approaches.

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• Best strategy for HTML parcial rendering based on multiple dropdown values

  - by pv2008

  I have a View that renders something like this: "Item 1" and "Item 2" are <tr> elements from a table. After the user change "Value 1" or "Value 2" I would like to call a Controller and put the result (some HTML snippet) in the div marked as "Result of...". I have some vague notions of JQuery. I know how to bind to the onchage event of the Select element, and call the $.ajax() function, for example. But I wonder if this can be achieved in a more efficient way in ASP.NET MVC2.

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• Adding new "columns" to csv data file in Tcl

  - by George

  Hi All, I am dealing with a "large" measurement data, approximately 30K key-value pairs. The measurements have number of iterations. After each iteration a datafile (non-csv) with 30K kay-value pairs is created. I want to somehow creata a csv file of form: Key1,value of iteration1,value of iteration2,... Key2,value of iteration1,value of iteration2,... Key2,value of iteration1,value of iteration2,... ... Now, I was wondering about efficient way of adding each iteration mesurement data as a columns to csv file in Tcl. So, far it seems that in either case I will need to load whole csv file into some variable(array/list) and work on each element by adding new measurement data. This seems somewhat inefficient. Is there another way, perhaps?

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• Python - Create a list with initial capacity

  - by Claudiu

  Code like this often happens: l = [] while foo: #baz l.append(bar) #qux This is really slow if you're about to append thousands of elements to your list, as the list will have to constantly be re-initialized to grow. (I understand that lists aren't just wrappers around some array-type-thing, but something more complicated. I think this still applies, though; let me know if not). In Java, you can create an ArrayList with an initial capacity. If you have some idea how big your list will be, this will be a lot more efficient. I understand that code like this can often be re-factored into a list comprehension. If the for/while loop is very complicated, though, this is unfeasible. Is there any equivalent for us python programmers?

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• Collection type generated by for with yield

  - by Jesper

  When I evaluate a for in Scala, I get an immutable IndexedSeq (a collection with array-like performance characteristics, such as efficient random access): scala> val s = for (i <- 0 to 9) yield math.random + i s: scala.collection.immutable.IndexedSeq[Double] = Vector(0.6127056766832756, 1.7137598183155291, ... Does a for with a yield always return an IndexedSeq, or can it also return some other type of collection class (a LinearSeq, for example)? If it can also return something else, then what determines the return type, and how can I influence it? I'm using Scala 2.8.0.RC3.

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• Using UIImageViews for 'pages' in an iPhone/iPad storybook app?

  - by outtoplayinc

  I'm new to iPhone programming, and well, what seems obvious to me may seem silly to a seasoned coder. I did a few 'switching views' tutorials on Youtube, and basically, they seems to work nicely for adding pages to a storybook type app. You add a UIViewController and associated view for each page. My question is would this become insanely slow, or a memory hog if I continued this method for say....35+ pages? Each page would also have a sound file associated with it that would play narration when a page load and stops when we leave. Basically, think of a powerpoint type app, with sound, possibly animated image elements, next & back buttons. I'm probably thinking of this very simplistically, but that's where my experience is at for the moment. Any insight or tips as to better and or more efficient ways to proceed would be greatly appreciated.

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• Effective way of String splitting C#

  - by openidsujoy

  I have a completed string like this N:Pay in Cash++RGI:40++R:200++T:Purchase++IP:N++IS:N++PD:PC++UCP:598.80++UPP:0.00++TCP:598.80++TPP:0.00++QE:1++QS:1++CPC:USD++PPC:Points++D:Y++E:Y++IFE:Y++AD:Y++IR:++MV:++CP:~ ~N:ERedemption++RGI:42++R:200++T:Purchase++IP:N++IS:N++PD:PC++UCP:598.80++UPP:0.00++TCP:598.80++TPP:0.00++QE:1++QS:1++CPC:USD++PPC:Points++D:Y++E:Y++IFE:Y++AD:Y++IR:++MV:++CP: this string is like this It's list of PO's(Payment Options) which are separated by ~~ this list may contains one or more PO contains only Key-Value Pairs which separated by : spaces are denoted by ++ I need to extract the values for Key "RGI" and "N". I can do it via for loop , I want a efficient way to do this. any help on this.

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• Hibernate Query - Get latest versions by timestamp?

  - by Slim

  I have a database that is being used as a sort of version control system. That is, instead of ever updating any rows, I add a new row with the same information. Each row also contains a version column that is a date timestamp, so the only difference is the new row will have a more recent timestamp. What I'm having trouble with is writing an efficient hibernate query to return the latest version of these rows. For the sake of example, these are rows in a table called Product, the timestamped column is version. There are multiple versions of multiple products in the table. So there may be multiple versions (rows) of ProductA, multiple versions of ProductB, etc. And I would like to grab the latest version of each. Can I do this in just a single hibernate query? session.createQuery("select product from Product product where...?"); Or would this require some intermediate steps?

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• Efficiently draw a grid in Windows Forms

  - by Joel

  I'm writing an implementation of Conway's Game of Life in C#. This is the code I'm using to draw the grid, it's in my panel_Paint event. g is the graphics context. for (int y = 0; y < numOfCells * cellSize; y += cellSize) { for (int x = 0; x < numOfCells * cellSize; x += cellSize) { g.DrawLine(p, x, 0, x, y + numOfCells * cellSize); g.DrawLine(p, 0, x, y + size * drawnGrid, x); } } When I run my program, it is unresponsive until it finishes drawing the grid, which takes a few seconds at numOfCells = 100 & cellSize = 10. Removing all the multiplication makes it faster, but not by very much. Is there a better/more efficient way to draw my grid? Thanks

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• Is there a single query that can update a "sequence number" across multiple groups?

  - by Drarok

  Given a table like below, is there a single-query way to update the table from this: | id | type_id | created_at | sequence | |----|---------|------------|----------| | 1 | 1 | 2010-04-26 | NULL | | 2 | 1 | 2010-04-27 | NULL | | 3 | 2 | 2010-04-28 | NULL | | 4 | 3 | 2010-04-28 | NULL | To this (note that created_at is used for ordering, and sequence is "grouped" by type_id): | id | type_id | created_at | sequence | |----|---------|------------|----------| | 1 | 1 | 2010-04-26 | 1 | | 2 | 1 | 2010-04-27 | 2 | | 3 | 2 | 2010-04-28 | 1 | | 4 | 3 | 2010-04-28 | 1 | I've seen some code before that used an @ variable like the following, that I thought might work: SET @seq = 0; UPDATE `log` SET `sequence` = @seq := @seq + 1 ORDER BY `created_at`; But that obviously doesn't reset the sequence to 1 for each type_id. If there's no single-query way to do this, what's the most efficient way? Data in this table may be deleted, so I'm planning to run a stored procedure after the user is done editing to re-sequence the table.

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• Generate custom marker (icon) out of two images in Leaflet

  - by Rmatt

  In Javascript/CoffeeScript, using Leaflet to display a map, I would like to have custom markers out of a two custom images, and also featuring a shadow for the pin : I want to have a "background" image with a color (or shape) to identify the category On top, I want to have inside this image a specific image (logo) for each pin I didn't find out how I could do that... Setting one image is quite easy but I don't know how to overlay them. I could also consider using a tool to superpose/group/overlay these images (locally ?) before in order to send only one to the Icon Leaflet Class, but also there, I wouldn't know which tool to use. Nevertheless, I still think that a double overlay would be more efficient and that my case could be useful for several people.

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• what good orm api will work well with scala or erlang

  - by Emotu Balogun

  I'm considering taking up scala programming but i'm really concerned about what will become of my ORM based applications. I currently use hibernate as my ORM and i find it a really reliable tool. I'd like to know if there's any ORM tool as efficient but written in scala, or will hibernate work seamlessly with it. i don't want to have to start writing endless sql queries again (like the days of JDBC). I also have the same thought about erlang. is there a good orm out there for erlang?? and can i use erlang with other DBMS like oracle and mysql with ORM

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• Ruby on Rails: Best way to save search queries in a database

  - by Adam Templeton

  For a RoR app I'm helping develop, I need to save all search queries in a database so I can analyze them later. My plan right now is to create a Result model and table, and just save each search query's text in that table, along with a user's ID, the time, etc. However, the app has about 15,000 users, so I'm afraid the single table approach won't be super efficient when it comes time to parse that data. (The database is setup via MySQL, if that factors in at all.) Am I just being paranoid? Is there a Ruby gem that handles this sort of thing, or a better approach I could take? Any input would be appreciated.

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• Image expire time

  - by Jens

  The google page speed tool recommends me to set 'Expires' headers for images etc. But what is the most efficient way to set an Expires header for an image? In now redirect all image requests to an imagehandler.php using htaccess: /* HTTP/1.1 404 Not Found, HTTP/1.1 400 Bad Request and content type detection stuff ... */ header( "Content-Type: " . $content_type ); header( "Cache-Control: public" ); header( "Last-Modified: ".gmdate("D, d M Y H:i:s", filemtime($path))." GMT"); header( "Expires: ". date("r",time() + (60*60*24*30))); readfile( $path ); But of course this adds extra loading time for my images on first request, and I was wondering if there was a better solution for this.

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• Javascript find if english alphabets only

  - by Alec Smart

  Hello, Am trying to find some text only if it contains english letters and numbers using Javascript/jQuery. Am wondering what is the most efficient way to do this? Since there could be thousands of words, it should be as fast as possible and I don't want to use regex. var names[0] = 'test'; var names[1] = '???'; var names[2] = '??????'; for (i=0;i<names.length;i++) { if (names[i] == ENGLISHMATCHCODEHERE) { // do something here } } Thank you for your time.

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• best method for creating a universal extention/plugin

  - by rashcroft44

  Hi, I'm looking to create an extension for the leading browsers (firefox, safari and ie). Its rather simple, and I'm looking for the most efficient way to go about this. I need to get the hostname of the current site the user is on, and if it matches a certain parameter(eg, mysite.org), I'll need to append to the link some extra data and refresh to the new link. What is the simplest way to go about this? (I don't want to go in the direction of a bookmarklet - since this would require the user to click. I'd like this to happen automatically) sort of something like this: if(window.location.hostname == 'mysite.org') { location.replace(document.location.href + '/&mystuff=xyz'); } Thanks!

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• Sorting 2 arrays that have been added together

  - by tyler

  In my app, users can create galleries that their work may or may not be in. Users have and belong to many Galleries, and each gallery has a 'creator' that is designated by the gallery's user_id field. So to get the 5 latest galleries a user is in, I can do something like: included_in = @user.galleries.order('created_at DESC').uniq.first(5) # SELECT DISTINCT "galleries".* FROM "galleries" INNER JOIN "galleries_users" ON "galleries"."id" = "galleries_users"."gallery_id" WHERE "galleries_users"."user_id" = 10 ORDER BY created_at DESC LIMIT 5 and to get the 5 latest galleries they've created, I can do: created = Gallery.where(user_id: id).order('created_at DESC').uniq.first(5) # SELECT DISTINCT "galleries".* FROM "galleries" WHERE "galleries"."user_id" = 10 ORDER BY created_at DESC LIMIT 5 I want to display these two together, so that it's the 5 latest galleries that they've created OR they're in. Something like the equivalent of: (included_in + created).order('created_at DESC').uniq.first(5) Does anyone know how to construct an efficient query or post-query loop that does this?

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• Is scala functional programming slower than traditional coding?

  - by Fred Haslam

  In one of my first attempts to create functional code, I ran into a performance issue. I started with a common task - multiply the elements of two arrays and sum up the results: var first:Array[Float] ... var second:Array[Float] ... var sum=0f; for(ix<-0 until first.length) sum += first(ix) * second(ix); Here is how I reformed the work: sum = first.zip(second).map{ case (a,b) => a*b }.reduceLeft(_+_) When I benchmarked the two approaches, the second method takes 40 times as long to complete! Why does the second method take so much longer? How can I reform the work to be both speed efficient and use functional programming style?

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• Mysql search design

  - by neil

  I'm designing a mysql database, and i'd like some input on an efficient way to store blog/article data for searching. Right now, I've made a separate column that stores the content to be searched - no duplicate words, no words shorter than four letters, and no words that are too common. So, essentially, it's a list of keywords from the original article. Also searched would be a list of tags, and the title field. I'm not quite sure how mysql indexes fulltext columns, so would storing the data like that be ineffective, or redundant somehow? A lot of the articles are on the same topic, so would the score be hurt by so many of the rows having similar keywords? Also, for this project, solutions like sphinx, lucene or google custom seach can't be used -- only php & mysql. Thanks!

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• C# GroupJoin effectiveness

  - by bsnote

  without using GroupJoin: var playersDictionary = players.ToDictionary(player => player.Id, element => new PlayerDto { Rounds = new List<RoundDto>() }); foreach (var round in rounds) { PlayerDto playerDto; playersDictionary.TryGetValue(round.PlayerId, out playerDto); if (playerDto != null) { playerDto.Rounds.Add(new RoundDto { }); } } var playerDtoItems = playersDictionary.Values; using GroupJoin: var playerDtoItems = from player in players join round in rounds on player.Id equals round.PlayerId into playerRounds select new PlayerDto { Rounds = playerRounds.Select(playerRound => new RoundDto {}) }; Which of these two pieces is more efficient?

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• solutions for rapid front-end development?

  - by fayer

  im using mvc framework and i have learned some techniques that help me with different parts of RAD. models: doctrine/visual paradigm controllers/libraries: various design patterns now i only need to know what technique/solution i should use for the views so that i can create views more rapidly. cause i don't think it's efficient to code css/html manually, even though i understand it. its the same principle when using visual paradigm to create both my mysql database tables and doctrine model classes. i believe in using right tools will boost up development speed. so what could i use for the views to save time and energy and don't reinvent the wheel all the time? dreamweaver? any css generation tools? 960/blueprint for layout? suggestions? thanks

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• C# GroupJoin efficiency

  - by bsnote

  without using GroupJoin: var playersDictionary = players.ToDictionary(player => player.Id, element => new PlayerDto { Rounds = new List<RoundDto>() }); foreach (var round in rounds) { PlayerDto playerDto; playersDictionary.TryGetValue(round.PlayerId, out playerDto); if (playerDto != null) { playerDto.Rounds.Add(new RoundDto { }); } } var playerDtoItems = playersDictionary.Values; using GroupJoin: var playerDtoItems = from player in players join round in rounds on player.Id equals round.PlayerId into playerRounds select new PlayerDto { Rounds = playerRounds.Select(playerRound => new RoundDto {}) }; Which of these two pieces is more efficient?

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• Which is more efficent PHP: array_intersect() OR array_intersect_key()

  - by Jordan Rutty

  Is it more efficient to use the key intersect or the value intersect if both key and value have the same contents for example: Array ( [743] => 743 [744] => 744 [745] => 745 [746] => 746 [747] => 747 [748] => 748 ) Is there any difference in performance in using one or the other with the same values. Similar to the difference of using double or single quotes?

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