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  • Most Efficient way to deal with multiple CCSprites?

    - by nardsurfer
    I have four different types of objects within my environment(box2d), each type of object having multiple instances of itself, and would like to find the most efficient way to deal with adding and manipulating all the CCSprites. The sprites are all from different files, so would it be best to create each sprite and add it to a data structure (NSMutableArray) or would I use a CCSpriteBatchNode even though each CCSprite file is different (for each type of object)? Thanks. @interface LevelScene : CCLayer { b2World* world; GLESDebugDraw *m_debugDraw; CCSpriteBatchNode *ballBatch; CCSpriteBatchNode *blockBatch; CCSpriteBatchNode *springBatch; CCSprite *goal; } +(id) scene; // adds a new sprite at a given coordinate -(void) addNewBallWithCoords:(CGPoint)p; // loads the objects (blocks, springs, and the goal), returns the Level Object -(Level) loadLevel:(int)level; @end or using NSMutableArray objects within the Level object... @interface zLevel : zThing { NSMutableArray *springs; NSMutableArray *blocks; NSMutableArray *balls; zGoal *goal; int levelNumber; } @property(nonatomic,retain)NSMutableArray *springs; @property(nonatomic,retain)NSMutableArray *blocks; @property(nonatomic,retain)NSMutableArray *balls; @property(nonatomic,retain)zGoal *goal; @property(nonatomic,assign)int levelNumber; -(void)initWithLevel:(int)level; -(void)loadLevelThings; @end

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  • Efficient way to call .Sum() on multiple properties

    - by SherCoder
    I have a function that uses Linq to get data from the database and then I call that function in another function to sum all the individual properties using .Sum on each individual property. I was wondering if there is an efficient way to sum all the properties at once rather than calling .Sum() on each individual property. I think the way I am doing as of right now, is very slow (although untested). public OminitureStats GetAvgOmnitureData(int? fnsId, int dateRange) { IQueryable<OminitureStats> query = GetOmnitureDataAsQueryable(fnsId, dateRange); int pageViews = query.Sum(q => q.PageViews); int monthlyUniqueVisitors = query.Sum(q => q.MonthlyUniqueVisitors); int visits = query.Sum(q => q.Visits); double pagesPerVisit = (double)query.Sum(q => q.PagesPerVisit); double bounceRate = (double)query.Sum(q => q.BounceRate); return new OminitureStats(pageViews, monthlyUniqueVisitors, visits, bounceRate, pagesPerVisit); }

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  • The most efficient way to calculate an integral in a dataset range

    - by Annalisa
    I have an array of 10 rows by 20 columns. Each columns corresponds to a data set that cannot be fitted with any sort of continuous mathematical function (it's a series of numbers derived experimentally). I would like to calculate the integral of each column between row 4 and row 8, then store the obtained result in a new array (20 rows x 1 column). I have tried using different scipy.integrate modules (e.g. quad, trpz,...). The problem is that, from what I understand, scipy.integrate must be applied to functions, and I am not sure how to convert each column of my initial array into a function. As an alternative, I thought of calculating the average of each column between row 4 and row 8, then multiply this number by 4 (i.e. 8-4=4, the x-interval) and then store this into my final 20x1 array. The problem is...ehm...that I don't know how to calculate the average over a given range. The question I am asking are: Which method is more efficient/straightforward? Can integrals be calculated over a data set like the one that I have described? How do I calculate the average over a range of rows?

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  • Java: Efficient Equivalent to Removing while Iterating a Collection

    - by Claudiu
    Hello everyone. We all know you can't do this: for (Object i : l) if (condition(i)) l.remove(i); ConcurrentModificationException etc... this apparently works sometimes, but not always. Here's some specific code: public static void main(String[] args) { Collection<Integer> l = new ArrayList<Integer>(); for (int i=0; i < 10; ++i) { l.add(new Integer(4)); l.add(new Integer(5)); l.add(new Integer(6)); } for (Integer i : l) { if (i.intValue() == 5) l.remove(i); } System.out.println(l); } This, of course, results in: Exception in thread "main" java.util.ConcurrentModificationException ...even though multiple threads aren't doing it... Anyway. What's the best solution to this problem? "Best" here means most time and space efficient (I realize you can't always have both!) I'm also using an arbitrary Collection here, not necessarily an ArrayList, so you can't rely on get.

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  • Looking for efficient scaling patterns for Silverlight application with distributed text-file data s

    - by Edward Tanguay
    I'm designing a Silverlight software solution for students and teachers to record flashcards, e.g. words and phrases that students find while reading and errors that teachers notice while teaching. Requirements are: each person publishes his own flashcards in a file on a web server, e.g. http://:www.mywebserver.com/flashcards.txt other people subscribe to that person's flashcards by using a Silverlight flashcard reader that I have developed and entering the URLs of flashcard files they want to subscribe to, URLs and imported flashcards being saved in IsolatedStorage the flashcards.txt file has the following simple format: title, then blocks of question/answers: Jim Smith's flashcards from English class 53-222, winter semester 2009 ==fla Das kann nicht sein. That can't be. ==fla Es sei denn, er kommt nicht. Unless he doesn't come. The user then makes public the URL to his flashcard file and other readers begin reading in his flashcards. In order to lower the bar for non-technical users to contribute, it will even be possible for them to save this text in a Google Document, which they publish and distribute the URL. The flashcard readers will then recognize it is a google document and perform the necessary screen scraping to get at the raw text. I have two technical questions about this approach: What is a best way to plan now for scalability issues: e.g. if your reader is subscribed to 10 flashcard files that are each 200K, it will have to download 2MB of text just to find out if any new flashcards are available. Or can I somehow accurately and consistently get at the last update date/time of text files on servers and published google docs? Each reader will have the ability to allow the person to test himself on imported flashcards and add meta information to them, e.g. categorize them, edit them, etc. This information will be stored in IsolatedStorage along with the important flashcards themselves. What is a good pattern to allow these readers to share and synchronize this meta data, e.g. so when you are looking at a flashcard you can see that 5 other people have made corrections to it. The best solution I can think of now is that the Silverlight readers will have to republish their data to a central database, but then there is the problem of uniquely identifying each flashcard, the best approach seems to be URL + position-in-file, or even better URL + original text of both question and answer fields, but both of these have their obvious drawbacks. The main requirement is that the bar for participation is kept as low as possible, i.e. type text in a google document, publish it, distribute the URL, and you're publishing within the flashcard community. So I want to come up with the most efficient technical solutions in order to compensate for the lack of database, lack of unique ids, etc. For those who have designed or developed similar non-traditional, distributed database projects like this, what advice, experience or best-practice tips you can share on the above two points?

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  • The most efficient method of drawing multiple quads in OpenGL

    - by CPatton
    I'm not very keen with OpenGL and I was wondering if someone could give me some insight on this. I'm a 'seasoned' programmer, I've read the redbook about VBOs and the like, but I was wondering from a more experienced person about the best/most efficient way of achieving this. I've been producing this 2d tile-based game engine to be used in several projects. I have a class called "ScreenObject" which is mainly composed of a Dictionary<Point, Tile> The Point key is to show where to render the Tile on the screen, and the Tile contains one or more textures to be drawn at that point. This ScreenObject is where the tiles will be modified, deleted, added, etc.. My original method of drawing the tiles in the testing I've done was to iterate through the ScreenObject and draw each quad at each location separately. From what I've read, this is a massive waste of resources. It wasn't horribly slow in the testing, but after I've completed the animation classes and effect classes, I'm sure it would be extremely slow. And one last thing, if you wouldn't mind.. As I said before, the Tile class can contain multiple textures to be drawn at the Point location on the screen. I recognize possibly two options for me here. Either add a quad at that location for each texture to be drawn, or, somehow.. use a multiple texture for the same quad (if it's possible). Even if each tile contained one texture only, that would be 64 quads to be drawn on the screen. Most of the tiles will contain 2-5 textures, so the number of total quads would increase dramatically with this method. Would it be feasible to add a quad for each new texture, or am I ignoring a better way to do this? Just need some help understanding this if you don't mind :) I've tried to be as concise as possible, and I'd greatly appreciate any responses.. and even some criticism. Programming is often a learning process and one who develops seems to never stops learning. Thanks for your time.

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  • How to make efficient code emerge through unit testing

    - by Jean
    Hi, I participate in a TDD Coding Dojo, where we try to practice pure TDD on simple problems. It occured to me however that the code which emerges from the unit tests isn't the most efficient. Now this is fine most of the time, but what if the code usage grows so that efficiency becomes a problem. I love the way the code emerges from unit testing, but is it possible to make the efficiency property emerge through further tests ? Here is a trivial example in ruby: prime factorization. I followed a pure TDD approach making the tests pass one after the other validating my original acceptance test (commented at the bottom). What further steps could I take, if I wanted to make one of the generic prime factorization algorithms emerge ? To reduce the problem domain, let's say I want to get a quadratic sieve implementation ... Now in this precise case I know the "optimal algorithm, but in most cases, the client will simply add a requirement that the feature runs in less than "x" time for a given environment. require 'shoulda' require 'lib/prime' class MathTest < Test::Unit::TestCase context "The math module" do should "have a method to get primes" do assert Math.respond_to? 'primes' end end context "The primes method of Math" do should "return [] for 0" do assert_equal [], Math.primes(0) end should "return [1] for 1 " do assert_equal [1], Math.primes(1) end should "return [1,2] for 2" do assert_equal [1,2], Math.primes(2) end should "return [1,3] for 3" do assert_equal [1,3], Math.primes(3) end should "return [1,2] for 4" do assert_equal [1,2,2], Math.primes(4) end should "return [1,5] for 5" do assert_equal [1,5], Math.primes(5) end should "return [1,2,3] for 6" do assert_equal [1,2,3], Math.primes(6) end should "return [1,3] for 9" do assert_equal [1,3,3], Math.primes(9) end should "return [1,2,5] for 10" do assert_equal [1,2,5], Math.primes(10) end end # context "Functionnal Acceptance test 1" do # context "the prime factors of 14101980 are 1,2,2,3,5,61,3853"do # should "return [1,2,3,5,61,3853] for ${14101980*14101980}" do # assert_equal [1,2,2,3,5,61,3853], Math.primes(14101980*14101980) # end # end # end end and the naive algorithm I created by this approach module Math def self.primes(n) if n==0 return [] else primes=[1] for i in 2..n do if n%i==0 while(n%i==0) primes<<i n=n/i end end end primes end end end

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  • Efficient list compacting

    - by Patrik
    Suppose you have a list of unsigned ints. Suppose some elements are equal to 0 and you want to push them back. Currently I use this code (list is a pointer to a list of unsigned ints of size n for (i = 0; i < n; ++i) { if (list[i]) continue; int j; for (j = i + 1; j < n && !list[j]; ++j); int z; for (z = j + 1; z < n && list[z]; ++z); if (j == n) break; memmove(&(list[i]), &(list[j]), sizeof(unsigned int) * (z - j))); int s = z - j + i; for(j = s; j < z; ++j) list[j] = 0; i = s - 1; } Can you think of a more efficient way to perform this task? The snippet is purely theoretical, in the production code, each element of list is a 64 bytes struct EDIT: I'll post my solution. Many thanks to Jonathan Leffler. void RemoveDeadParticles(int * list, int * n) { int i, j = *n - 1; for (; j >= 0 && list[j] == 0; --j); for (i = 0; i < j; ++i) { if (list[i]) continue; memcpy(&(list[i]), &(list[j]), sizeof(int)); list[j] = 0; for (; j >= 0 && list[j] == 0; --j); if (i == j) break; } *n = i + 1; }

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  • Efficient algorithm to distribute work?

    - by Zwei Steinen
    It's a bit complicated to explain but here we go. We have problems like this (code is pseudo-code, and is only for illustrating the problem. Sorry it's in java. If you don't understand, I'd be glad to explain.). class Problem { final Set<Integer> allSectionIds = { 1,2,4,6,7,8,10 }; final Data data = //Some data } And a subproblem is: class SubProblem { final Set<Integer> targetedSectionIds; final Data data; SubProblem(Set<Integer> targetedSectionsIds, Data data){ this.targetedSectionIds = targetedSectionIds; this.data = data; } } Work will look like this, then. class Work implements Runnable { final Set<Section> subSections; final Data data; final Result result; Work(Set<Section> subSections, Data data) { this.sections = SubSections; this.data = data; } @Override public void run(){ for(Section section : subSections){ result.addUp(compute(data, section)); } } } Now we have instances of 'Worker', that have their own state sections I have. class Worker implements ExecutorService { final Map<Integer,Section> sectionsIHave; { sectionsIHave = {1:section1, 5:section5, 8:section8 }; } final ExecutorService executor = //some executor. @Override public void execute(SubProblem problem){ Set<Section> sectionsNeeded = fetchSections(problem.targetedSectionIds); super.execute(new Work(sectionsNeeded, problem.data); } } phew. So, we have a lot of Problems and Workers are constantly asking for more SubProblems. My task is to break up Problems into SubProblem and give it to them. The difficulty is however, that I have to later collect all the results for the SubProblems and merge (reduce) them into a Result for the whole Problem. This is however, costly, so I want to give the workers "chunks" that are as big as possible (has as many targetedSections as possible). It doesn't have to be perfect (mathematically as efficient as possible or something). I mean, I guess that it is impossible to have a perfect solution, because you can't predict how long each computation will take, etc.. But is there a good heuristic solution for this? Or maybe some resources I can read up before I go into designing? Any advice is highly appreciated!

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  • Is this postgres function cost efficient or still have to clean

    - by kiranking
    There are two tables in postgres db. english_all and english_glob First table contains words like international,confidential,booting,cooler ...etc I have written the function to get the words from english_all then perform for loop for each word to get word list which are not inserted in anglish_glob table. Word list is like I In Int Inte Inter .. b bo boo boot .. c co coo cool etc.. for some reason zwnj(zero-width non-joiner) is added during insertion to english_all table. But in function I am removing that character with regexp_replace. Postgres function for_loop_test is taking two parameter min and max based on that I am selecting words from english_all table. function code is like DECLARE inMinLength ALIAS FOR $1; inMaxLength ALIAS FOR $2; mviews RECORD; outenglishListRow english_word_list;--custom data type eng_id,english_text BEGIN FOR mviews IN SELECT id,english_all_text FROM english_all where wlength between inMinLength and inMaxLength ORDER BY english_all_text limit 30 LOOP FOR i IN 1..char_length(regexp_replace(mviews.english_all_text,'(?)$','')) LOOP FOR outenglishListRow IN SELECT distinct on (regexp_replace((substring(mviews.english_all_text from 1 for i)),'(?)$','')) mviews.id, regexp_replace((substring(mviews.english_all_text from 1 for i)),'(?)$','') where regexp_replace((substring(mviews.english_all_text from 1 for i)),'(?)$','') not in(select english_glob.english_text from english_glob where i=english_glob.wlength) order by regexp_replace((substring(mviews.english_all_text from 1 for i)),'(?)$','') LOOP RETURN NEXT outenglishListRow; END LOOP; END LOOP; END LOOP; END; Once I get the word list I will insert that into another table english_glob. My question is is there any thing I can add to or remove from function to make it more efficient. edit Let assume english_all table have words like footer,settle,question,overflow,database,kingdom If inMinLength = 5 and inmaxLength=7 then in the outer loop footer,settle,kingdom will be selected. For above 3 words inner two loop will apply to get words like f,fo,foo,foot,foote,footer,s,se,set,sett,settl .... etc. In the final process words which are bold will be entered into english_glob with another parameter like 1 to denote it is a proper word and stored in the another filed of english_glob table. Remaining word will be stored with another parameter 0 because in the next call words which are saved in database should not be fetched again. edit2: This is a complete code CREATE TABLE english_all ( id serial NOT NULL, english_all_text text NOT NULL, wlength integer NOT NULL, CONSTRAINT english_all PRIMARY KEY (id), CONSTRAINT english_all_kan_text_uq_id UNIQUE (english_all_text) ) CREATE TABLE english_glob ( id serial NOT NULL, english_text text NOT NULL, is_prop integer default 1, CONSTRAINT english_glob PRIMARY KEY (id), CONSTRAINT english_glob_kan_text_uq_id UNIQUE (english_text) ) insert into english_all(english_text) values ('ant'),('forget'),('forgive'); on function call with parameter 3 and 6 fallowing rows should fetched a an ant f fo for forg forge forget next is insert to another table based on above row insert into english_glob(english_text,is_prop) values ('a',1),('an',1), ('ant',1),('f',0), ('fo',0),('for',1), ('forg',0),('forge',1), ('forget',1), on function call next time with parameter 3 and 7 fallowing rows should fetched.(because f,fo,for,forg are all entered in english_glob table) forgi forgiv forgive

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  • Making an efficient algorithm

    - by James P.
    Here's my recent submission for the FB programming contest (qualifying round only requires to upload program output so source code doesn't matter). The objective is to find two squares that add up to a given value. I've left it as it is as an example. It does the job but is too slow for my liking. Here's the points that are obviously eating up time: List of squares is being recalculated for each call of getNumOfDoubleSquares(). This could be precalculated or extended when needed. Both squares are being checked for when it is only necessary to check for one (complements). There might be a more efficient way than a double-nested loop to find pairs. Other suggestions? Besides this particular problem, what do you look for when optimizing an algorithm? public static int getNumOfDoubleSquares( Integer target ){ int num = 0; ArrayList<Integer> squares = new ArrayList<Integer>(); ArrayList<Integer> found = new ArrayList<Integer>(); int squareValue = 0; for( int j=0; squareValue<=target; j++ ){ squares.add(j, squareValue); squareValue = (int)Math.pow(j+1,2); } int squareSum = 0; System.out.println( "Target=" + target ); for( int i = 0; i < squares.size(); i++ ){ int square1 = squares.get(i); for( int j = 0; j < squares.size(); j++ ){ int square2 = squares.get(j); squareSum = square1 + square2; if( squareSum == target && !found.contains( square1 ) && !found.contains( square2 ) ){ found.add(square1); found.add(square2); System.out.println( "Found !" + square1 +"+"+ square2 +"="+ squareSum); num++; } } } return num; }

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  • Writing an optimised and efficient search engine with mySQL and ColdFusion

    - by Mel
    I have a search page with the following scenarios listed below. I was told there was a better way to do it, but not how, and that I am using too many if statements, and that it's prone to causing an error through url manipulation: Search.cfm will processes a search made from a search bar present on all pages, with one search input (titleName). If search.cfm is accessed manually (through URL not through using the simple search bar on all pages) it displays an advanced search form with three inputs (titleName, genreID, platformID) or it evaluates searchResponse variable and decides what to do. If simple search query is blank, has no results, or less than 3 characters it displays an error If advanced search query is blank, has no results, or less than 3 characters it displays an error If any successful search returns results, they come back normally. The top-of-page logic is as follows: <!---SET DEFAULT VARIABLE---> <cfparam name="variables.searchResponse" default=""> <!---CHECK TO SEE IF SIMPLE SEARCH A FORM WAS SUBMITTED AND EXECUTE SEARCH IF IT WAS---> <cfif IsDefined("Form.simpleSearch") AND Len(Trim(Form.titleName)) LTE 2> <cfset variables.searchResponse = "invalidString"> <cfelseif IsDefined("Form.simpleSearch") AND Len(Trim(Form.titleName)) GTE 3> <!---EXECUTE METHOD AND GET DATA---> <cfinvoke component="myComponent" method="simpleSearch" searchString="#Form.titleName#" returnvariable="simpleSearchResult"> <cfset variables.searchResponse = "simpleSearchResult"> </cfif> <!---CHECK IF ANY RECORDS WERE FOUND---> <cfif IsDefined("variables.simpleSearchResult") AND simpleSearchResult.RecordCount IS 0> <cfset variables.searchResponse = "noResult"> </cfif> <!---CHECK IF ADVANCED SEARCH FORM WAS SUBMITTED---> <cfif IsDefined("Form.AdvancedSearch") AND Len(Trim(Form.titleName)) LTE 2> <cfset variables.searchResponse = "invalidString"> <cfelseif IsDefined("Form.advancedSearch") AND Len(Trim(Form.titleName)) GTE 2> <!---EXECUTE METHOD AND GET DATA---> <cfinvoke component="myComponent" method="advancedSearch" returnvariable="advancedSearchResult" titleName="#Form.titleName#" genreID="#Form.genreID#" platformID="#Form.platformID#"> <cfset variables.searchResponse = "advancedSearchResult"> </cfif> <!---CHECK IF ANY RECORDS WERE FOUND---> <cfif IsDefined("variables.advancedSearchResult") AND advancedSearchResult.RecordCount IS 0> <cfset variables.searchResponse = "noResult"> </cfif> I'm using the searchResponse variable to decide what the the page displays, based on the following scenarios: <!---ALWAYS DISPLAY SIMPLE SEARCH BAR AS IT'S PART OF THE HEADER---> <form name="simpleSearch" action="search.cfm" method="post"> <input type="hidden" name="simpleSearch" /> <input type="text" name="titleName" /> <input type="button" value="Search" onclick="form.submit()" /> </form> <!---IF NO SEARCH WAS SUBMITTED DISPLAY DEFAULT FORM---> <cfif searchResponse IS ""> <h1>Advanced Search</h1> <!---DISPLAY FORM---> <form name="advancedSearch" action="search.cfm" method="post"> <input type="hidden" name="advancedSearch" /> <input type="text" name="titleName" /> <input type="text" name="genreID" /> <input type="text" name="platformID" /> <input type="button" value="Search" onclick="form.submit()" /> </form> </cfif> <!---IF SEARCH IS BLANK OR LESS THAN 3 CHARACTERS DISPLAY ERROR MESSAGE---> <cfif searchResponse IS "invalidString"> <cfoutput> <h1>INVALID SEARCH</h1> </cfoutput> </cfif> <!---IF SEARCH WAS MADE BUT NO RESULTS WERE FOUND---> <cfif searchResponse IS "noResult"> <cfoutput> <h1>NO RESULT FOUND</h1> </cfoutput> </cfif> <!---IF SIMPLE SEARCH WAS MADE A RESULT WAS FOUND---> <cfif searchResponse IS "simpleSearchResult"> <cfoutput> <h1>Search Results</h1> </cfoutput> <cfoutput query="simpleSearchResult"> <!---DISPLAY QUERY DATA---> </cfoutput> </cfif> <!---IF ADVANCED SEARCH WAS MADE A RESULT WAS FOUND---> <cfif searchResponse IS "advancedSearchResult"> <cfoutput> <h1>Search Results</h1> <p>Your search for "#Form.titleName#" returned #advancedSearchResult.RecordCount# result(s).</p> </cfoutput> <cfoutput query="advancedSearchResult"> <!---DISPLAY QUERY DATA---> </cfoutput> </cfif> Is my logic a) not efficient because my if statements/is there a better way to do this? And b) Can you see any scenarios where my code can break? I've tested it but I have not been able to find any issues with it. And I have no way of measuring performance. Any thoughts and ideas would be greatly appreciated. Many thanks

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  • Smart Phones Shockingly Energy Efficient; Lead to Decreased Household Power Consumption

    - by Jason Fitzpatrick
    Given how often our smart phones and tablets spend plugged in and topping off their battery reserves, it’s easy to assume they’re sucking down a lot of power. Analysis shows the lilliputian but powerful devices are surprisingly efficient and may be decreasing our overall power consumption. Courtesy of energy-centric blog Outlier, we’re treated to a look at the power sipping habits of popular smart phones and mobile devices. The simple take away? They use shockingly little electricity over the course of the year–you can charge your new iPhone for a year of regular usage for under a buck. The more complex analysis? The proliferation of tiny and energy efficient devices is displacing heavier energy consumers (large televisions, desktop computers, etc.) and driving a more efficient gadget-to-consumption ratio is many households. Hit up the link below to read the full post. How Much Does It Take to Charge an iPhone [via Mashable] 7 Ways To Free Up Hard Disk Space On Windows HTG Explains: How System Restore Works in Windows HTG Explains: How Antivirus Software Works

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  • What is an Efficient algorithm to find Area of Overlapping Rectangles

    - by namenlos
    My situation Input: a set of rectangles each rect is comprised of 4 doubles like this: (x0,y0,x1,y1) they are not "rotated" at any angle, all they are "normal" rectangles that go "up/down" and "left/right" with respect to the screen they are randomly placed - they may be touching at the edges, overlapping , or not have any contact I will have several hundred rectangles this is implemented in C# I need to find The area that is formed by their overlap - all the area in the canvas that more than one rectangle "covers" (for example with two rectangles, it would be the intersection) I don't need the geometry of the overlap - just the area (example: 4 sq inches) Overlaps shouldn't be counted multiple times - so for example imagine 3 rects that have the same size and position - they are right on top of each other - this area should be counted once (not three times) Example The image below contains thre rectangles: A,B,C A and B overlap (as indicated by dashes) B and C overlap (as indicated by dashes) What I am looking for is the area where the dashes are shown - AAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAA--------------BBB AAAAAAAAAAAAAAAA--------------BBB AAAAAAAAAAAAAAAA--------------BBB AAAAAAAAAAAAAAAA--------------BBB BBBBBBBBBBBBBBBBB BBBBBBBBBBBBBBBBB BBBBBBBBBBBBBBBBB BBBBBB-----------CCCCCCCC BBBBBB-----------CCCCCCCC BBBBBB-----------CCCCCCCC CCCCCCCCCCCCCCCCCCC CCCCCCCCCCCCCCCCCCC CCCCCCCCCCCCCCCCCCC CCCCCCCCCCCCCCCCCCC

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  • Memory efficient way of inserting an array of objects with Core Data

    - by randombits
    I'm working on a piece of code for an iPhone application that fetches a bunch of data from a server and builds objects from it on the client. It ends up creating roughly 40,000 objects. They aren't displayed to the user, I just need to create instances of NSManagedObject and store them to persistent storage. Am I wrong in thinking that the only way to do this is to create a single object, then save the context? is it best to create the objects all at once, then somehow save them to the context after they're created and stored in some set or array? If so, can one show some example code for how this is done or point me in the direction to code where this is done? The objects themselves are relatively straight forward models with string or integer attributes and don't contain any complex relationships.

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  • Finding most efficient transmission size in varying network latency scenarios

    - by rwmnau
    I'm building a .NET remoting client/server that will be transmitting thousands of files, of varying sizes (everything from a few bytes to hundreds of MB), and I'm curious about a general method for finding the appropriate transmission size. As I see it, there's the following tradeoff: Serialize entire file into a transmission object and transmit at once, regardless of size. This would be the fastest, but a failure during tranmission requires that the whole file be re-transmitted. If the file size is larger than something small (like 4KB), break it into 4KB chunks and transmit those, re-assembling on the server. In addition to the complexity of this, it's slower because of continued round-trips and acknowledgements, though a failure of any one piece doesn't waste much time. The ideal transmission method (when taking into account negotiation latency vs. failure rate) is somewhere in between, and I'm wondering about how to find out the best size for that particular client. Do I have some dynamic tuning step in my transmission that looks at the current bytes/second average, and then raises the transmission size until the speed starts to drop (failures overwhelm negotiation cost)? Or is there some other method for determining ideal transmission size? The application will be multi-threaded, so number of threads also factors in to the calculation. I'm not looking for a formula (though I'll take one if you've got it), but just what to consider as I create this process.

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  • Writing an efficient cron job script utilizing Zend_Mail_Storage_Imap.

    - by fireeyedboy
    I'm new to the IMAP protocol and Zend_Mail_Storage and I'm writing a small php script for a cron job that should regularly poll an IMAP account and check for new messages, and send an e-mail if new messages have arrived. As you can imagine, I want to only poll the IMAP account for relevant messages, and I only want to send a new e-mail if new messages have arrived since the last polled new message. So I thought of keeping track of the last message I polled with some unique identifier for a message. But I'm a bit uncertain about whether the methods I want to utilize for this do what I expect them to do though. So my questions are: Does the iterator position of Zend_Mail_Storage_Imap actually resemble some IMAP unique identifier for messages, or is it simply only and internal position of Zend_Mail_Storage_Abstract? For instance, if I tell it to seek() to message 5 (which I stored from an earlier session) will it indeed seek to the appropriate message on the IMAP server, even if for instance messages have been deleted since last session? Would keeping track of this latest polled message id in a file suffice for a cron job that, say, polls the account every 5 or 10 minutes? Or is this too naive, and should I be using a database for instance. Or is there maybe a much easier way to keep track of such state with Zend_Mail_Storage_Abstract? Also, do I need to poll every IMAP folder? Or is everything accumulated when I poll INBOX? If you could shed some light on any of these matters, I'ld appreciate it. Thanks in advance.

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  • More efficient programming than Web.py?

    - by Luke Stanley
    I love webpy, it's really quite Pythonic but I don't like having to add the url mappings and create a class, typically with just 1 function inside it. I'm interested in minimising code typing and prototyping fast. Does anyone have any up and coming suggestions such as Bobo, Bottle, Denied, cherrypy for a lover of webpy's good things? What makes it a good reason? Also I don't mind missing out (strongly) text based templating systems, I use object oriented HTML generation.

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  • Most efficient way of creating tree from adjacency list

    - by Jeff Meatball Yang
    I have an adjacency list of objects (rows loaded from SQL database with the key and it's parent key) that I need to use to build an unordered tree. It's guaranteed to not have cycles. This is taking wayyy too long (processed only ~3K out of 870K nodes in about 5 minutes). Running on my workstation Core 2 Duo with plenty of RAM. Any ideas on how to make this faster? public class StampHierarchy { private StampNode _root; private SortedList<int, StampNode> _keyNodeIndex; // takes a list of nodes and builds a tree // starting at _root private void BuildHierarchy(List<StampNode> nodes) { Stack<StampNode> processor = new Stack<StampNode>(); _keyNodeIndex = new SortedList<int, StampNode>(nodes.Count); // find the root _root = nodes.Find(n => n.Parent == 0); // find children... processor.Push(_root); while (processor.Count != 0) { StampNode current = processor.Pop(); // keep a direct link to the node via the key _keyNodeIndex.Add(current.Key, current); // add children current.Children.AddRange(nodes.Where(n => n.Parent == current.Key)); // queue the children foreach (StampNode child in current.Children) { processor.Push(child); nodes.Remove(child); // thought this might help the Where above } } } } public class StampNode { // properties: int Key, int Parent, string Name, List<StampNode> Children }

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  • Make Python Socket Server More Efficient

    - by BenMills
    I have very little experience working with sockets and multithreaded programming so to learn more I decided to see if I could hack together a little python socket server to power a chat room. I ended up getting it working pretty well but then I noticed my server's CPU usage spiked up over 100% when I had it running in the background. Here is my code in full: http://gist.github.com/332132 I know this is a pretty open ended question so besides just helping with my code are there any good articles I could read that could help me learn more about this? My full code: import select import socket import sys import threading from daemon import Daemon class Server: def __init__(self): self.host = '' self.port = 9998 self.backlog = 5 self.size = 1024 self.server = None self.threads = [] self.send_count = 0 def open_socket(self): try: self.server = socket.socket(socket.AF_INET6, socket.SOCK_STREAM) self.server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) self.server.bind((self.host,self.port)) self.server.listen(5) print "Server Started..." except socket.error, (value,message): if self.server: self.server.close() print "Could not open socket: " + message sys.exit(1) def remove_thread(self, t): t.join() def send_to_children(self, msg): self.send_count = 0 for t in self.threads: t.send_msg(msg) print 'Sent to '+str(self.send_count)+" of "+str(len(self.threads)) def run(self): self.open_socket() input = [self.server,sys.stdin] running = 1 while running: inputready,outputready,exceptready = select.select(input,[],[]) for s in inputready: if s == self.server: # handle the server socket c = Client(self.server.accept(), self) c.start() self.threads.append(c) print "Num of clients: "+str(len(self.threads)) self.server.close() for c in self.threads: c.join() class Client(threading.Thread): def __init__(self,(client,address), server): threading.Thread.__init__(self) self.client = client self.address = address self.size = 1024 self.server = server self.running = True def send_msg(self, msg): if self.running: self.client.send(msg) self.server.send_count += 1 def run(self): while self.running: data = self.client.recv(self.size) if data: print data self.server.send_to_children(data) else: self.running = False self.server.threads.remove(self) self.client.close() """ Run Server """ class DaemonServer(Daemon): def run(self): s = Server() s.run() if __name__ == "__main__": d = DaemonServer('/var/servers/fserver.pid') if len(sys.argv) == 2: if 'start' == sys.argv[1]: d.start() elif 'stop' == sys.argv[1]: d.stop() elif 'restart' == sys.argv[1]: d.restart() else: print "Unknown command" sys.exit(2) sys.exit(0) else: print "usage: %s start|stop|restart" % sys.argv[0] sys.exit(2)

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  • Most efficient algorithm for merging sorted IEnumerable<T>

    - by franck
    Hello, I have several huge sorted enumerable sequences that I want to merge. Theses lists are manipulated as IEnumerable but are already sorted. Since input lists are sorted, it should be possible to merge them in one trip, without re-sorting anything. I would like to keep the defered execution behavior. I tried to write a naive algorithm which do that (see below). However, it looks pretty ugly and I'm sure it can be optimized. It may exist a more academical algorithm... IEnumerable<T> MergeOrderedLists<T, TOrder>(IEnumerable<IEnumerable<T>> orderedlists, Func<T, TOrder> orderBy) { var enumerators = orderedlists.ToDictionary(l => l.GetEnumerator(), l => default(T)); IEnumerator<T> tag = null; var firstRun = true; while (true) { var toRemove = new List<IEnumerator<T>>(); var toAdd = new List<KeyValuePair<IEnumerator<T>, T>>(); foreach (var pair in enumerators.Where(pair => firstRun || tag == pair.Key)) { if (pair.Key.MoveNext()) toAdd.Add(pair); else toRemove.Add(pair.Key); } foreach (var enumerator in toRemove) enumerators.Remove(enumerator); foreach (var pair in toAdd) enumerators[pair.Key] = pair.Key.Current; if (enumerators.Count == 0) yield break; var min = enumerators.OrderBy(t => orderBy(t.Value)).FirstOrDefault(); tag = min.Key; yield return min.Value; firstRun = false; } } The method can be used like that: // Person lists are already sorted by age MergeOrderedLists(orderedList, p => p.Age); assuming the following Person class exists somewhere: public class Person { public int Age { get; set; } } Duplicates should be conserved, we don't care about their order in the new sequence. Do you see any obvious optimization I could use?

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  • addSublayer vs addSubView which is more efficient?

    - by soonio
    I have 5 UIImageViews for displaying 5 images. For my app, I need swap the order of them depending on some events. I achieve this by calling: [anImageView1 removeFromSuperview]; [self.view insertSubview:anImageView1 aboveSubview:anImageView2]; Recently, I've come across a different method for doing this using 1 UIView and 5 UIImageViews. Each layer of UIImageViews are added to this UIView by calling [aView.layer addSublayer:anImageView1.layer]; [aView.layer addSublayer:anImageView2.layer]; etc. and then in order to swap the order of things by calling [anImageView1.layer removeFromSuperLayer]; [aView.layer insertSublayer:anImageView1 above: anImageView2] Both methods work fine, but can someone please point out which method is better and why? I really can't seem to be able to find much on CALayer... Please help! Thank you so much!

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