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  • Function calculating the probability of a letter in an sentence

    - by Mike
    I have a function that is supposed to calculate the number of times a letter occurs in a sentence, and based on that, calculate the probability of it occurring in the sentence. To accomplish this, I have a sentence: The Washington Metropolitan Area is the most educated and affluent metropolitan area in the United States. An array of structures, containing the letter, the number of times it occurs, and the probability of it occurring, with one structure for each letter character and an additional structure for punctuation and spaces: struct letters { char letter; int occur; double prob; }box[53]; This is the function itself: void probability(letters box[53], int sum { cout<<sum<<endl<<endl; for(int c8=0;c8<26;c8++) { box[c8].prob = (box[c8].occur/sum); cout<<box[c8].letter<<endl; cout<<box[c8].occur<<endl; cout<<box[c8].prob<<endl<<endl; } } It correctly identifies that there are 90 letters in the sentence in the first line, prints out the uppercase letter as per the structure in the second line of the for loop, and prints out the number of times it occurs. It continually prints 0 for the probability. What am I doing wrong?

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  • Questions on Juval Lowy's IDesign C# Coding Standard

    - by Jan
    We are trying to use the IDesign C# Coding standard. Unfortunately, I found no comprehensive document to explain all the rules that it gives, and also his book does not always help. Here are the open questions that remain for me (from chapter 2, Coding Practices): No. 26: Avoid providing explicit values for enums unless they are integer powers of 2 No. 34: Always explicitly initialize an array of reference types using a for loop No. 50: Avoid events as interface members No. 52: Expose interfaces on class hierarchies No. 73: Do not define method-specific constraints in interfaces No. 74: Do not define constraints in delegates Here's what I think about those: I thought that providing explicit values would be especially useful when adding new enum members at a later point in time. If these members are added between other already existing members, I would provide explicit values to make sure the integer representation of existing members does not change. No idea why I would want to do this. I'd say this totally depends on the logic of my program. I see that there is alternative option of providing "Sink interfaces" (simply providing already all "OnXxxHappened" methods), but what is the reason to prefer one over the other? Unsure what he means here: Could this mean "When implementing an interface explicitly in a non-sealed class, consider providing the implementation in a protected virtual method that can be overridden"? (see Programming .NET Components 2nd Edition, end of chapter “Interfaces and Class Hierarchies”). I suppose this is about providing a "where" clause when using generics, but why is this bad on an interface? I suppose this is about providing a "where" clause when using generics, but why is this bad on a delegate?

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  • Performing measures within the execution of a c++ code every t milliseconds

    - by user506901
    Given a while loop and the function ordering as follows: int k=0; int total=100; while(k<total){ doSomething(); if(approx. t milliseconds elapsed) { measure(); } ++k; } I want to perform 'measure' every t-th milliseconds. However, since 'doSomething' can be close to the t-th millisecond from the last execution, it is acceptable to perform the measure after approximately t milliseconds elapsed from the last measure. My question is: how could this be achieved? One solution would be to set timer to zero, and measure it after every 'doSomething'. When it is withing the acceptable range, I perform measures, and reset. However, I'm not which c++ function I should use for such a task. As I can see, there are certain functions, but the debate on which one is the most appropriate is outside of my understanding. Note that some of the functions actually take into account the time taken by some other processes, but I want my timer to only measure the time of the execution of my c++ code (I hope that is clear). Another thing is the resolution of the measurements, as pointed out below. Suppose the medium option of those suggested.

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  • Finding the digit root of a number

    - by Jessica M.
    Study question is to find the digit root of a already provided number. The teacher provides us with the number 2638. In order to find the digit root you have to add each digit separately 2 + 6 + 3 + 8 = 19. Then you take the result 19 and add those two digits together 1 + 9 = 10. Do the same thing again 1 + 0 = 1. The digit root is 1. My first step was to use the variable total to add up the number 2638 to find the total of 19. Then I tried to use the second while loop to separate the two digits by using the % I have to try and solve the problem by using basic integer arithmetic (+, -, *, /). 1.Is it necessary and or possible to solve the problem using nested while loops? 2.Is my math correct? 3. As I wrote it here it does not run in Eclipse. Am I using the while loops correctly? import acm.program.*; public class Ch4Q7 extends ConsoleProgram { public void run(){ println("This program attempts to find the digit root of your number: "); int n = readInt("Please enter your number: "); int total = 0; int root = total; while (n > 0 ){ total = total + (n %10); n = (n / 10); } while ( total > 0 ){ root = total; total = ((total % 10) + total / 10); } println("your root should be " + root); } }

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  • Two Objects created with the same Address in Flex

    - by James
    Hi, I have an issue in flex which is causing a bit of a headache! I am adding objects to an ArrayCollection but in doing so, another ArrayCollection is also picking up these changes even though there is no binding occurring. I can see from the debug that the two ACs have the same address but for the life of me can't figure out why. I have two Array Collections: model.index.rows //The main array collection model.index.holdRows //The array collection that imitates the above This phantom data binding occurs only for the first iteration in the loop and for all others it will just write it the once. The reason this is proving troublesome is that it creates duplicate entries in my datagrid. public override function handleMessage(message:IMessage):void { super.handleMessage(message); if (message is IndexResponse) { var response:IndexResponse = message as IndexResponse; model.index.rows.removeAll(); model.index.indexIsEmpty = response.nullIndex; if (model.index.indexIsEmpty !== true) { //Update the index model from the response. Note: each property of the row object will be shown in the UI as a column in the grid response.index.forEach(function(entry:EntryData, i:int, a:Array):void { var row:Object = { fileID: entry.fileID, dadName: entry.dadName }; entry.tags.forEach(function(tag:Tag, i:int, a:Array):void { row[tag.name] = tag.value; }); model.index.rows.addItem(row); }); if(model.index.indexForNetworkView == true){ model.index.holdRows.source = model.index.holdRows.source.concat(model.index.rows.source); model.index.indexCounter++; model.index.indexForNetworkView = false; controller.indexController.showNetwork(model.index.indexCounter); } model.index.rows.refresh(); controller.networkController.show(); } } Has anyone else who has encountered something simillar propose a solution?

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  • In perl, how can I call a method whose name I have in a string?

    - by Ryan Thompson
    I'm trying to write some abstract code for searching through a list of similar objects for the first one whose attributes match specific values. In order to do this, I need to call a bunch of accessor methods and check all their values one by one. I'd like to use an abstraction like this: sub verify_attribute { my ($object, $attribute_method, $wanted_value) = @_; if ( call_method($object, $attribute_method) ~~ $wanted_value ) { return 1; } else { return; } } Then I can loop through a hash whose keys are accessor method names and whose values are the values I'm looking for for those attributes. For example, if that hash is called %wanted, I might use code like this to find the object I want: my $found_object; FINDOBJ: foreach my $obj (@list_of_objects) { foreach my $accessor (keys %wanted) { next FINDOBJ unless verify_attribute($obj, $accessor, $wanted{$accessor}); } # All attrs verified $found_object = $obj; last FINDOBJ; } Of course, the only problem is that call_method does not exsit. Or does it? How can I call a method if I have a string containing its name? Or is there a better solution to this whole problem?

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  • All Callbacks on GUI Thread - Multithreading issues possible?

    - by miguel
    We have an external data provider which, in its construtor, takes a callback thread for returning data upon. There are some issues in the system which I am suspicious are related to threading, however, in theory they cannot be, due to the fact that the callbacks should all be returned on the same thread. My question is, does code like this require thread synchronisation? class Foo { ExternalDataProvider _provider; public Foo() { // This is the c'tor for the xternal data provider, taking a callback loop as param _provider = new ExternalDataProvider(UILoop); _provider.DataArrived += ExternalProviderCallbackMethod; } public ExternalProviderCallbackMethod(...) { //...(code omitted) var itemArray[] = new String[4] { "item1", "item2", "item3", "item4" }; for (int i = 0; i < itemArray.Length; i++) { string s = itemArray[i]; switch(s) { case "item1": DoItem1Action(); break; case "item2": DoItem2Action(); break; default: DoDefaultAction(); break; } //...(code omitted) } } } The issue is that, very infrequently, DoItem2Action is executingwhen DoItem1Action should be exectuing. Is it at all possible threading is at fault here? In theory, as all callbacks are arriving on the same thread, they should be serialized, right? So there should be no need for thread sync here?

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  • Callbacks on GUI Thread

    - by miguel
    We have an external data provider which, in its construtor, takes a callback thread for returning data upon. There are some issues in the system which I am suspicious are related to threading, however, in theory they cannot be, due to the fact that the callbacks should all be returned on the same thread. My question is, does code like this require thread synchronisation? class Foo { ExternalDataProvider _provider; public Foo() { // This is the c'tor for the xternal data provider, taking a callback loop as param _provider = new ExternalDataProvider(UILoop); _provider.DataArrived += ExternalProviderCallbackMethod; } public ExternalProviderCallbackMethod() { var itemArray[] = new String[4] { "item1", "item2", "item3", "item4" }; for (int i = 0; i < itemArray.Length; i++) { string s = itemArray[i]; switch(s) { case "item1": DoItem1Action(); break; case "item2": DoItem2Action(); break; default: DoDefaultAction(); break; } } } } The issue is that, very infrequently, DoItem2Action is executingwhen DoItem1Action should be exectuing. Is it at all possible threading is at fault here? In theory, as all callbacks are arriving on the same thread, they should be serialized, right? So there should be no need for thread sync here?

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  • GetIpAddrTable() leaks memory. How to resolve that?

    - by Stabledog
    On my Windows 7 box, this simple program causes the memory use of the application to creep up continuously, with no upper bound. I've stripped out everything non-essential, and it seems clear that the culprit is the Microsoft Iphlpapi function "GetIpAddrTable()". On each call, it leaks some memory. In a loop (e.g. checking for changes to the network interface list), it is unsustainable. There seems to be no async notification API which could do this job, so now I'm faced with possibly having to isolate this logic into a separate process and recycle the process periodically -- an ugly solution. Any ideas? // IphlpLeak.cpp - demonstrates that GetIpAddrTable leaks memory internally: run this and watch // the memory use of the app climb up continuously with no upper bound. #include <stdio.h> #include <windows.h> #include <assert.h> #include <Iphlpapi.h> #pragma comment(lib,"Iphlpapi.lib") void testLeak() { static unsigned char buf[16384]; DWORD dwSize(sizeof(buf)); if (GetIpAddrTable((PMIB_IPADDRTABLE)buf, &dwSize, false) == ERROR_INSUFFICIENT_BUFFER) { assert(0); // we never hit this branch. return; } } int main(int argc, char* argv[]) { for ( int i = 0; true; i++ ) { testLeak(); printf("i=%d\n",i); Sleep(1000); } return 0; }

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  • Understanding Async Concept in WebServices

    - by 8EM
    I've had the thrill recently of developing web service applications. Most of my experience is with GWT and mainly doing most things on the client side then doing an async call back for any additional data needed. However at the moment, I want a process that will be triggered on the client side, then on the server side, a loop will occur, where if a certain condition is met, it will 'push' back to the client. This will hopefully remove the processor usage on the client side and also saves bandwidth. What is this called? I understand 'polling' is where the client side continuously hits a server, however what I want is the opposite. Is this possible? Am I misunderstanding what happened when I trigger an AsyncService in GWT? Please advise. EDIT: Just for further clarification: Having some kind of weather data service. Where, you trigger 'go' on the client side, then on the server side, it checks to see the degrees, if it has moved since last time, it will spit back the degrees to the client, if it hasn't, it will keep looping.

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  • Objective C: Function returning correct data for the first time of call and null for other times

    - by Kooshal Bhungy
    Hi all, Am a beginner in objective C, i am implementing a function that would query a web server and display the returning string in console. I am calling the function (getDatafromServer) repeatedly in a loop. The problem is that the first time am getting the value whereas the other times, it returns me a (null) in console... I've searched about memory management and check out on the forums but none have worked. Can you please guys tell me where am wrong in the codes below? Thanks in advance.... @implementation RequestThread +(void)startthread:(id)param{ while (true) { //NSLog(@"Test threads"); sleep(5); NSLog(@"%@",[self getDatafromServer]); } } +(NSString *) getDatafromServer{ NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; NSString *myRequestString = @"name=Hello%20&[email protected]"; NSData *myRequestData = [NSData dataWithBytes:[myRequestString UTF8String] length:[myRequestString length]]; NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL: [NSURL URLWithString:@"http://192.168.1.32/gs/includes/widget/getcalls.php?user=asdasd&passw=asdasdasd"]]; [request setHTTPMethod:@"POST"]; [request setHTTPBody: myRequestData]; [request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"content-type"]; NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil]; NSString *myString = [NSString stringWithUTF8String:[returnData bytes]]; [myRequestString release]; [request release]; [returnData release]; return myString; [pool release]; } @end

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  • How to get timestamp of tick precision in .NET / C#?

    - by Hermann
    Up until now I used DateTime.Now for getting timestamps, but I noticed that if you print DateTime.Now in a loop you will see that it increments in descrete jumps of approx. 15 ms. But for certain scenarios in my application I need to get the most accurate timestamp possible, preferably with tick (=100 ns) precision. Any ideas? Update: Apparently, StopWatch / QueryPerformanceCounter is the way to go, but it can only be used to measure time, so I was thinking about calling DateTime.Now when the application starts up and then just have StopWatch run and then just add the elapsed time from StopWatch to the initial value returned from DateTime.Now. At least that should give me accurate relative timestamps, right? What do you think about that (hack)? NOTE: StopWatch.ElapsedTicks is different from StopWatch.Elapsed.Ticks! I used the former assuming 1 tick = 100 ns, but in this case 1 tick = 1 / StopWatch.Frequency. So to get ticks equivalent to DateTime use StopWatch.Elapsed.Ticks. I just learned this the hard way. NOTE 2: Using the StopWatch approach, I noticed it gets out of sync with the real time. After about 10 hours, it was ahead by 5 seconds. So I guess one would have to resync it every X or so where X could be 1 hour, 30 min, 15 min, etc. I am not sure what the optimal timespan for resyncing would be since every resync will change the offset which can be up to 20 ms.

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  • PHP Form multiple buttons

    - by Ken
    I have a form with 2 buttons, that depending on which is selected will either be deleted or edited from the database. Those are each individual pages using SQL statements (questionedit and questiondelete). However, when i press a button, nothing happens...Any Ideas Here is my javascript <script type="text/javascript"> function SelectedButton(button) { if(button == 'edit') { document.testedit_questionform.action ="testedit_questionedit.php"; } else if(button == 'delete') { document.testedit_questionform.action ="testedit_questiondelete.php"; } document.forms[].testedit_questionform.submit(); } </script> Here is my form (being echoed from a loop) <form name=\"testedit_questionform\" action=\"SelectedButton\" method=\"POST\"> <span class=\"grid_11 prefix_1\" id=\"\" > Question:<input type=\"text\" name=\"QuestionText\" style=\"width:588px; margin-left:10px;\" value=\"$row[0]\"/> <input type=\"button\" value=\"Edit\" name=\"Operation\"onclick=\"submitForm(\'edit\')\" /> <input type=\"button\" value=\"Delete\" name=\"Operation\"onclick=\"submitForm(\'delete\')\" /> <input type=\"hidden\" name=\"QId\" value=\"$row[3]\" /><br />"); </form>

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  • What's the proper approach for writing multi-path "story" flows?

    - by Basiclife
    Hi, I wonder if you can help me. I'm writing a game (2d) which allows players to take multiple routes, some of which branch/merge - perhaps even loop. Each section of the game will decide which section is loaded next. I'm calling each section an IStoryElement - And I'm wondering how best to link these elements up in a way that is easily changed/configured and at the same time, graphable I'm going to have an engine/factory assembly which will load the appropriate StoryElement(s) based on various config options. I initially planned to give each StoryElement a NextElement() As IStoryElement property and a Completed() event. When the vent fires, the engine reads the NextElement property to find the next StoryElement. The downside to this is that if I ever wanted to graph all the routes through the game, I would be unable to - I couldn't determine all possible targets for each StoryElement. I considered a couple of other solutions but they all feel a little clunky - eg Do I need an additional layer of abstraction? ie StoryElementPlayers or similar - Each one would be responsible for stringing together multiple StoryElement perhaps a Series and a ChoicePlayer with each responsible for graphing its own StoryElement - But this will just move the problem up a layer. In short, I need some way of emulating a simple but dynamic workflow (but I'd rather not actually use WWF). Is there a pattern for something this simple? All the ones I've managed to find relate to more advanced control flow (parallel processing, etc.)

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  • Callers block until getFoo() has a value ready?

    - by Sean Owen
    I have a Java Thread which exposes a property which other threads want to access: class MyThread extends Thread { private Foo foo; ... Foo getFoo() { return foo; } ... public void run() { ... foo = makeTheFoo(); ... } } The problem is that it takes some short time from the time this runs until foo is available. Callers may call getFoo() before this and get a null. I'd rather they simply block, wait, and get the value once initialization has occurred. (foo is never changed afterwards.) It will be a matter of milliseconds until it's ready, so I'm comfortable with this approach. Now, I can make this happen with wait() and notifyAll() and there's a 95% chance I'll do it right. But I'm wondering how you all would do it; is there a primitive in java.util.concurrent that would do this, that I've missed? Or, how would you structure it? Yes, make foo volatile. Yes, synchronize on an internal lock Object and put the check in a while loop until it's not null. Am I missing anything?

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  • Computation overhead in C# - Using getters/setters vs. modifying arrays directly and casting speeds

    - by Jeffrey Kern
    I was going to write a long-winded post, but I'll boil it down here: I'm trying to emulate the graphical old-school style of the NES via XNA. However, my FPS is SLOW, trying to modify 65K pixels per frame. If I just loop through all 65K pixels and set them to some arbitrary color, I get 64FPS. The code I made to look-up what colors should be placed where, I get 1FPS. I think it is because of my object-orented code. Right now, I have things divided into about six classes, with getters/setters. I'm guessing that I'm at least calling 360K getters per frame, which I think is a lot of overhead. Each class contains either/and-or 1D or 2D arrays containing custom enumerations, int, Color, or Vector2D, bytes. What if I combined all of the classes into just one, and accessed the contents of each array directly? The code would look a mess, and ditch the concepts of object-oriented coding, but the speed might be much faster. I'm also not concerned about access violations, as any attempts to get/set the data in the arrays will done in blocks. E.g., all writing to arrays will take place before any data is accessed from them. As for casting, I stated that I'm using custom enumerations, int, Color, and Vector2D, bytes. Which data types are fastest to use and access in the .net Framework, XNA, XBox, C#? I think that constant casting might be a cause of slowdown here. Also, instead of using math to figure out which indexes data should be placed in, I've used precomputed lookup tables so I don't have to use constant multiplication, addition, subtraction, division per frame. :)

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  • Reduce file size for charts pasted from excel into word

    - by Steve Clanton
    I have been creating reports by copying some charts and data from an excel document into a word document. I am pasting into a content control, so i use ChartObject.CopyPicture in excel and ContentControl.Range.Paste in word. This is done in a loop: Set ws = ThisWorkbook.Worksheets("Charts") With ws For Each cc In wordDocument.ContentControls If cc.Range.InlineShapes.Count > 0 Then scaleHeight = cc.Range.InlineShapes(1).scaleHeight scaleWidth = cc.Range.InlineShapes(1).scaleWidth cc.Range.InlineShapes(1).Delete .ChartObjects(cc.Tag).CopyPicture Appearance:=xlScreen, Format:=xlPicture cc.Range.Paste cc.Range.InlineShapes(1).scaleHeight = scaleHeight cc.Range.InlineShapes(1).scaleWidth = scaleWidth ElseIf ... Next cc End With Creating these reports using Office 2007 yielded files that were around 6MB, but creating them (using the same worksheet and document) in Office 2010 yields a file that is around 10 times as large. After unzipping the docx, I found that the extra size comes from emf files that correspond to charts that are pasted in using VBA. Where they range from 360 to 900 KB before, they are 5-18 MB. And the graphics are not visibly better. I am able to CopyPicture with the format xlBitmap, and while that is somewhat smaller, it is larger than the emf generated by Office 2007 and noticeably poorer quality. Are there any other options for reducing the file size? Ideally, I would like to produce a file with the same resolution for the charts as I did using Office 2007. Is there any way that uses VBA only (without modifying the charts in the spreadsheet)?

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  • Vectorize matrix operation in R

    - by Fernando
    I have a R x C matrix filled to the k-th row and empty below this row. What i need to do is to fill the remaining rows. In order to do this, i have a function that takes 2 entire rows as arguments, do some calculations and output 2 fresh rows (these outputs will fill the matrix). I have a list of all 'pairs' of rows to be processed, but my for loop is not helping performance: # M is the matrix # nrow(M) and k are even, so nLeft is even M = matrix(1:48, ncol = 3) # half to fill k = nrow(M)/2 # simulate empty rows to be filled M[-(1:k), ] = 0 cat('before fill') print(M) # number of empty rows to fill nLeft = nrow(M) - k nextRow = k + 1 # list of rows to process (could be any order of non-empty rows) idxList = matrix(1:k, ncol = 2) for ( i in 1 : (nLeft / 2)) { row1 = M[idxList[i, 1],] row2 = M[idxList[i, 2],] # the two columns in 'results' will become 2 rows in M # fake result, return 2*row1 and 3*row2 results = matrix(c(2*row1, 3*row2), ncol = 2) # fill the matrix M[nextRow, ] = results[, 1] nextRow = nextRow + 1 M[nextRow, ] = results[, 2] nextRow = nextRow + 1 } cat('after fill') print(M) I tried to vectorize this, but failed... appreciate any help on improving this code, thanks!

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  • Runtime Error 1004 using Select with several workbooks

    - by Johaen
    I have an Excel workbook which pulls out data from two other workbooks. Since the data changes hourly there is the possibility that this macro is used more than one time a day for the same data. So I just want to select all previous data to this date period and want to delete them. Later on the data will be copied in anyway. But as soon as I want to use WBSH.Range(Cells(j, "A"), Cells(lastRow - 1, "M")).Select the code stopes with Error 1004 Application-defined or object-defined error. Followed just a snippet of the code with the relevant part. What is wrong here? 'Set source workbook Dim currentWb As Workbook Set currentWb = ThisWorkbook Set WBSH = currentWb.Sheets("Tracking") 'Query which data from the tracking files shoud get pulled out to the file CheckDate = Application.InputBox(("From which date you want to get data?" & vbCrLf & "Format: yyyy/mm/dd "), "Tracking data", Format(Date - 1, "yyyy/mm/dd")) 'states the last entry which is done ; know where to start ; currentWb File With currentWb.Sheets("Tracking") lastRow = .Range("D" & .Rows.Count).End(xlUp).Row lastRow = lastRow + 1 End With 'just last 250 entries get checked since not so many entries are made in one week j = lastRow - 250 'Check if there is already data to the look up date in the analyses sheet and if so deletes these records Do j = j + 1 'Exit Sub if there is no data to compare to prevent overflow If WBSH.Cells(j + 1, "C").Value = "" Then Exit Do End If Loop While WBSH.Cells(j, "C").Value < CheckDate If j <> lastRow - 1 Then 'WBSH.Range(Cells(j, "A"), Cells(lastRow - 1, "M")).Select 'Selection.ClearContents End If Thank you!

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  • Optimizing a "set in a string list" to a "set as a matrix" operation

    - by Eric Fournier
    I have a set of strings which contain space-separated elements. I want to build a matrix which will tell me which elements were part of which strings. For example: "" "A B C" "D" "B D" Should give something like: A B C D 1 2 1 1 1 3 1 4 1 1 Now I've got a solution, but it runs slow as molasse, and I've run out of ideas on how to make it faster: reverseIn <- function(vector, value) { return(value %in% vector) } buildCategoryMatrix <- function(valueVector) { allClasses <- c() for(classVec in unique(valueVector)) { allClasses <- unique(c(allClasses, strsplit(classVec, " ", fixed=TRUE)[[1]])) } resMatrix <- matrix(ncol=0, nrow=length(valueVector)) splitValues <- strsplit(valueVector, " ", fixed=TRUE) for(cat in allClasses) { if(cat=="") { catIsPart <- (valueVector == "") } else { catIsPart <- sapply(splitValues, reverseIn, cat) } resMatrix <- cbind(resMatrix, catIsPart) } colnames(resMatrix) <- allClasses return(resMatrix) } Profiling the function gives me this: $by.self self.time self.pct total.time total.pct "match" 31.20 34.74 31.24 34.79 "FUN" 30.26 33.70 74.30 82.74 "lapply" 13.56 15.10 87.86 97.84 "%in%" 12.92 14.39 44.10 49.11 So my actual questions would be: - Where are the 33% spent in "FUN" coming from? - Would there be any way to speed up the %in% call? I tried turning the strings into factors prior to going into the loop so that I'd be matching numbers instead of strings, but that actually makes R crash. I've also tried going for partial matrix assignment (IE, resMatrix[i,x] <- 1) where i is the number of the string and x is the vector of factors. No dice there either, as it seems to keep on running infinitely.

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  • How to optimize paging for large in memory database

    - by snakefoot
    I have an application where the entire database is implemented in memory using a stl-map for each table in the database. Each item in the stl-map is a complex object with references to other items in the other stl-maps. The application works with a large amount of data, so it uses more than 500 MByte RAM. Clients are able to contact the application and get a filtered version of the entire database. This is done by running through the entire database, and finding items relevant for the client. When the application have been running for an hour or so, then Windows 2003 SP2 starts to page out parts of the RAM for the application (Eventhough there is 16 GByte RAM on the machine). After the application have been partly paged out then a client logon takes a long time (10 mins) because it now generates a page fault for each pointer lookup in the stl-map. I can see it is possible to tell Windows to lock memory in RAM, but this is generally only recommended for device drivers, and only for "small" amounts of memory. I guess a poor mans solution could be to loop through the entire memory database, and thus tell Windows we are still interested in keeping the datamodel in RAM. I guess another poor mans solution could be to disable the pagefile completely on Windows. I guess the expensive solution would be a SQL database, and then rewrite the entire application to use a database layer. Then hopefully the database system will have implemented means to for fast access. Are there other more elegant solutions ?

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  • How to insert several thousand columns into sqlite3?

    - by user291071
    Similar to my last question, but I ran into problem lets say I have a simple dictionary like below but its Big, when I try inserting a big dictionary using the methods below I get operational error for the c.execute(schema) for too many columns so what should be my alternate method to populate an sql databases columns? Using the alter table command and add each one individually? import sqlite3 con = sqlite3.connect('simple.db') c = con.cursor() dic = { 'x1':{'y1':1.0,'y2':0.0}, 'x2':{'y1':0.0,'y2':2.0,'joe bla':1.5}, 'x3':{'y2':2.0,'y3 45 etc':1.5} } # 1. Find the unique column names. columns = set() for _, cols in dic.items(): for key, _ in cols.items(): columns.add(key) # 2. Create the schema. col_defs = [ # Start with the column for our key name '"row_name" VARCHAR(2) NOT NULL PRIMARY KEY' ] for column in columns: col_defs.append('"%s" REAL NULL' % column) schema = "CREATE TABLE simple (%s);" % ",".join(col_defs) c.execute(schema) # 3. Loop through each row for row_name, cols in dic.items(): # Compile the data we have for this row. col_names = cols.keys() col_values = [str(val) for val in cols.values()] # Insert it. sql = 'INSERT INTO simple ("row_name", "%s") VALUES ("%s", "%s");' % ( '","'.join(col_names), row_name, '","'.join(col_values) )

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  • c# Convert LINQ var result to actual type

    - by DrBob
    In c#, Given the following code: public class Person { public int PersonID { get; set; } public int Age { get; set; } public string Name { get; set; } } and List<Person> people = new List<Person>(); for (int i = 0; i != 15; i++) { Person p = new Person(); p.PersonID = i; p.Age = i * 12; p.Name = "Name " + i; people.Add(p); } var sortedPeople = from qPeople in people where qPeople.Age > 0 && qPeople.Age < 25 || qPeople.Age > 100 orderby qPeople.Age descending select qPeople; Can I load the results of sortedPeople back into a List<Person without a loop? Thanks.

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  • Freeing ImageData when deleting a Canvas

    - by user578770
    I'm writing a XUL application using HTML Canvas to display Bitmap images. I'm generating ImageDatas and imporingt them in a canvas using the putImageData function : for(var pageIndex=0;pageIndex<100;pageIndex++){ this.img = imageDatas[pageIndex]; /* Create the Canvas element */ var imgCanvasTmp = document.createElementNS("http://www.w3.org/1999/xhtml",'html:canvas'); imgCanvasTmp.setAttribute('width', this.img.width); imgCanvasTmp.setAttribute('height', this.img.height); /* Import the image into the Canvas */ imgCanvasTmp.getContext('2d').putImageData(this.img, 0, 0); /* Use the Canvas into another part of the program (Commented out for testing) */ // this.displayCanvas(imgCanvasTmp,pageIndex); } The images are well imported but there seems to be a memory leak due to the putImageData function. When exiting the "for" loop, I would expect the memory allocated for the Canvas to be freed but, by executing the code without executing putImageData, I noticed that my program at the end use 100Mb less (my images are quite big). I came to the conclusion that the putImageData function prevent the garbage collector to free the allocated memory. Do you have any idea how I could force the garbage collector to free the memory? Is there any way to empty the Canvas? I already tried to delete the canvas using the delete operator or to use the clearRect function but it did nothing. I also tried to reuse the same canvas to display the image at each iteration but the amount of memory used did not changed, as if the image where imported without deleting the existing ones...

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  • Why does JavaScript's getElementsByClassName provide an object that is NOT an array?

    - by Paragon
    I'm trying to get a list in JavaScript (not using jQuery) of all the elements on the page with a specific class name. I therefore employ the getElementsByClassName() function as follows: var expand_buttons = document.getElementsByClassName('expand'); console.log(expand_buttons, expand_buttons.length, expand_buttons[0]); Note that I have three anchor elements on my page with the class 'expand'. This console.log() outputs [] 0 undefined Next, for kicks, I threw expand_buttons into its own array as follows: var newArray = new Array(expand_buttons); console.log(newArray, newArray.length); This suddenly outputs [NodeList[3]] 1 and I can click through the nodelist and see the attributes of the three 'expand' anchor elements on the page. It's also worth noting that I was able to get my code working in a w3schools test page. It may also be of note that my use of document.getElementsByName actually does output (to the console) an array of elements, but when I ask for its length, it tells me 0. Similarly, if I try to access an array element using array_name[0] as normal, it outputs 'undefined', despite there clearly being an element inside of an array when I print the object to the console. Does anybody have any idea why this might be? I just want to loop through DOM elements, and I'm avoiding jQuery at the moment because I'm trying to practice coding with vanilla JavaScript. Thanks, ParagonRG

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