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  • What was that tutorial on pointers?

    - by pecker
    Hello, I once read a tutorial/article on Pointers somewhere. It was not a general tutorial but it explained how to clearly understand the complex & confusing pointers (especially like the ones that are usually asked in interview). It was more like http://www.codeweblog.com/right-left-rule-complex-pointer-analysis/ I'm unable to find it. Could any one post it here. PS: I did tried to google it but couldn't find. I'm asking it here because I thought it was popular.

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  • How to make Visual C++ 9 not emit code that is actually never called?

    - by sharptooth
    My native C++ COM component uses ATL. In DllRegisterServer() I call CComModule::RegisterServer(): STDAPI DllRegisterServer() { return _Module.RegisterServer(FALSE); // <<< notice FALSE here } FALSE is passed to indicate to not register the type library. ATL is available as sources, so I in fact compile the implementation of CComModule::RegisterServer(). Somewhere down the call stack there's an if statement: if( doRegisterTypeLibrary ) { //<< FALSE goes here // do some stuff, then call RegisterTypeLib() } The compiler sees all of the above code and so it can see that in fact the if condition is always false, yet when I inspect the linker progress messages I see that the reference to RegisterTypeLib() is still there, so the if statement is not eliminated. Can I make Visual C++ 9 perform better static analysis and actually see that some code is never called and not emit that code?

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  • XNA or C# Pop-up progress bar for the LoadContent() method

    - by Warlax
    Hey people, We wrote a small game using Microsoft's XNA Game Studio 3.1. The LoadContent() takes a long time because, other than loading models, and config files, we're also running some one-time (per run) terrain analysis. We are not C# or XNA programmers... we're Java programmers, and want to be able to give the user some feedback that the system is loading. Preferably, this will be through a simple pop-up with a progress bar that will say something simple like "loading please wait". The progress bar doesn't have to be a 0 to 1 progress bar, it can instead be one of those 'back and forth' progress bars. I was hoping for some quick copy-paste ready code to just do that - as it is not a central piece of our project, nor do we have a need to delve into too much documentation. I appreciate you time, effort, and possible donation. Thanks.

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  • Convert object to DateRange

    - by user655832
    I'm querying an underlying PostgreSQL database using Pandas 0.8. Pandas is returning the DataFrame properly but the underlying timestamp column in my database is being returned as a generic "object" type in Pandas. As I would eventually like to seasonal normalization of my data I am curious as to how to convert this generic "object" column to something that is appropriate for analysis. Here is my current code to retrieve the data: # get records from db example import pandas.io.sql as psql import psycopg2 # define query to get all subs created this year QRY = """ select i i, i * random() f, case when random() > 0.5 then true else false end t, (current_date - (i*random())::int)::timestamp with time zone tsz from generate_series(1,1000) as s(i) order by 4 ; """ CONN_STRING = "host='localhost' port=5432 dbname='postgres' user='postgres'" # connect to db conn = psycopg2.connect(CONN_STRING) # get some data set index on relid column df = psql.frame_query(QRY, con=conn) print "Row count retrieved: %i" % (len(df),) Thanks for any help you can render. M

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  • How to get the top keys from a hash by value

    - by Kirs Kringle
    I have a hash that I sorted by values greatest to least. How would I go about getting the top 5? There was a post on here that talked about getting only one value. What is the easiest way to get a key with the highest value from a hash in Perl? I understand that so would lets say getting those values add them to an array and delete the element in the hash and then do the process again? Seems like there should be an easier way to do this then that though. My hash is called %words. use strict; use warnings; use Tk; #Learn to install here: http://factscruncher.blogspot.com/2012/01/easy-way-to-install-tk- on-strawberry.html #Reading in the text file my $file0 = Tk::MainWindow->new->Tk::getOpenFile; open( my $filehandle0, '<', $file0 ) || die "Could not open $file0\n"; my @words; while ( my $line = <$filehandle0> ) { chomp $line; my @word = split( /\s+/, lc($line)); push( @words, @word ); } for (@words) { s/[\,|\.|\!|\?|\:|\;|\"]//g; } #Counting words that repeat; put in hash my %words_count; $words_count{$_}++ for @words; #Reading in the stopwords file my $file1 = "stoplist.txt"; open( my $filehandle1, '<', $file1 ) or die "Could not open $file1\n"; my @stopwords; while ( my $line = <$filehandle1> ) { chomp $line; my @linearray = split( " ", $line ); push( @stopwords, @linearray ); } for my $w ( my @stopwords ) { s/\b\Q$w\E\B//ig; } #Comparing the array to Hash and deleteing stopwords my %words = %words_count; for my $stopwords ( @stopwords ) { delete $words{ $stopwords }; } #Sorting Hash Table my @keys = sort { $words{$b} <=> $words{$a} or "\L$a" cmp "\L$b" } keys %words; #Starting Statistical Work my $value_count = 0; my $key_count = 0; #Printing Hash Table $key_count = keys %words; foreach my $key (@keys) { $value_count = $words{$key} + $value_count; printf "%-20s %6d\n", $key, $words{$key}; } my $value_average = $value_count / $key_count; #my @topwords; #foreach my $key (@keys){ #if($words{$key} > $value_average){ # @topwords = keys %words; # } #} print "\n", "The number of values: ", $value_count, "\n"; print "The number of elements: ", $key_count, "\n"; print "The Average: ", $value_average, "\n\n";

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  • Screening (multi)collinearity in a reggresion model

    - by aL3xa
    I hope that this one is not going to be "ask-and-answer" question... here goes: (multi)collinearity refers to extremely high correlations between predictors in the regression model. How to cure them... well, sometimes you don't need to "cure" collinearity, since it doesn't affect regression model itself, but interpretation of an effect of individual predictors. One way to spot collinearity is to put each predictor as a dependent variable, and other predictors as independent variables, determine R2, and if it's larger than .9 (or .95), we can consider predictor redundant. This is one "method"... what about other approaches? Some of them are time consuming, like excluding predictors from model and watching for b-coefficient changes - they should be noticeably different. Of course, we must always bare in mind specific context/goal of analysis... Sometimes, only remedy is to repeat a research, but right now, I'm interested in various ways of screening redundant predictors when (multi)collinearity occurs in a regression model.

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  • How does one modify the thread scheduling behavior when using Threading Building Blocks (TBB)?

    - by J Teller
    Does anyone know how to modify the thread scheduling (specifically affinity) when using TBB? Doing a high level analysis on a simple parallel-for application, it seems like TBB is specifying the underlying threads' affinity in a way that reduces performance. Specifically, the cores I'm running on have hyper-threading enabled, and it looks like TBB is affinitizing threads to the same core even if there is a different core left completely unloaded. FWIW, I realize it's likely that TBB is doing the "right thing" and that changing the threads' affinity will only reduce performance. I'd just like to experiment with it to see if that's really the case.

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  • Screen capture during testing

    - by Edwward
    This is an application for reviewing performance tests. Simple in concept, tricky to describe. Picture: 1) Recording interactions with a WPF program so the inputs can be played back. 2) Playing the inputs back while doing a continuous screen capture. 3) Capturing wall time as well as continuous CPU percentages during playback. 4) Repeating steps (2) and (3) lots of times. 5) Writing the relevant stuff out to files/db. 6) Reading it and putting it all in a fancy UI for easy review/analysis. The killer for me is (2). I could use some guidance on a good, possibly commercial, screen capture SDK. I would also welcome the news that my whole problem already has a solution. And of course any thoughts on the overall idea would also be great. Thanks. Ed

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  • Java resource management: please help to understand Findbugs results.

    - by java.is.for.desktop
    Hello, everyone! Findbugs bugs me about a method which opens two Closeable instances, but I can't understand why. Source public static void sourceXmlToBeautifiedXml(File input, File output) throws TransformerException, IOException, JAXBException { FileReader fileReader = new FileReader(input); FileWriter fileWriter = new FileWriter(output); try { // may throw something sourceXmlToBeautifiedXml(fileReader, fileWriter); } finally { try { fileReader.close(); } finally { fileWriter.close(); } } } Findbugs analysis Findbugs tells me Method [...] may fail to clean up java.io.Reader [...] and points to the line with FileReader fileReader = ... Question Who is wrong: me or Findbugs?

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  • Have you switched from CodeIgniter to Kohana?

    - by Eli
    Hi All, I usually just work with straight PHP, but want to try MVC and see if a framework will really speed up development. After much waffling, analysis paralysis, and many dumb SO questions, I thought I had settled on CodeIgniter for my next PHP project. However, I am now seriously considering Kohana. Has anyone made the switch from CI to Kohana? If so, why? What's better about the actual code, libraries, etc? Edit: Hi All, I did end up going with Kohana. It's easy to use, but more importantly, it's easy NOT to use, since there are a lot of things I like to work with native PHP for. It's ridiculously extensible, well coded, and seems like it is beginning to pull out ahead of CI in a few things like putting views in views, passing subview data, etc. I am sure CI will catch up, but Kohana should be 3 steps ahead by then =o)

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  • Leak caused by fread

    - by Jack
    I'm profiling code of a game I wrote and I'm wondering how it is possible that the following snippet causes an heap increase of 4kb (I'm profiling with Heapshot Analysis of Xcode) every time it is executed: u8 WorldManager::versionOfMap(FILE *file) { char magic[4]; u8 version; fread(magic, 4, 1, file); <-- this is the line fread(&version,1,1,file); fseek(file, 0, SEEK_SET); return version; } According to the profiler the highlighted line allocates 4.00Kb of memory with a malloc every time the function is called, memory which is never released. This thing seems to happen with other calls to fread around the code, but this was the most eclatant one. Is there anything trivial I'm missing? Is it something internal I shouldn't care about? Just as a note: I'm profiling it on an iPhone and it's compiled as release (-O2).

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  • Performance Overhead of Perf Event Subsystem in Linux Kernel

    - by Bo Xiao
    Performance counters for Linux are a new kernel-based subsystem that provide a framework for all things performance analysis. It covers hardware level (CPU/PMU, Performance Monitoring Unit) features and software features (software counters, tracepoints) as well. Since 2.6.33, the kernel provide 'perf_event_create_kernel_counter' kernel api for developers to create kernel counter to collect system runtime information. What I concern most is the performance impact on overall system when tracepoint/ftrace is enabled. There are no docs I can find about them. I was once told that ftrace was implemented by dynamically patching code, will it slow the system dramatically?

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  • Processing an n-ary ANTLR AST one child at a time

    - by Chris Lieb
    I currently have a compiler that uses an AST where all children of a code block are on the same level (ie, block.children == {stm1, stm2, stm3, etc...}). I am trying to do liveness analysis on this tree, which means that I need to take the value returned from the processing of stm1 and then pass it to stm2, then take the value returned by stm2 and pass it to stm3, and so on. I do not see a way of executing the child rules in this fashion when the AST is structured this way. Is there a way to allow me to chain the execution of the child grammar items with my given AST, or am I going to have to go through the painful process of refactoring the parser to generate a nested structure and updating the rest of the compiler to work with the new AST? Example ANTLR grammar fragment: block : ^(BLOCK statement*) ; statement : // stuff ; What I hope I don't have to go to: block : ^(BLOCK statementList) ; statementList : ^(StmLst statement statement+) | ^(StmLst statement) ; statement : // stuff ;

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  • Extracting rightmost N bits of an integer

    - by srandpersonia
    In the yester Code Jam Qualification round http://code.google.com/codejam/contest/dashboard?c=433101#s=a&a=0 , there was a problem called Snapper Chain. From the contest analysis I came to know the problem requires bit twiddling stuff like extracting the rightmost N bits of an integer and checking if they all are 1. I saw a contestant's(Eireksten) code which performed the said operation like below: (((K&(1<<N)-1))==(1<<N)-1) I couldn't understand how this works. What is the use of -1 there in the comparison?. If somebody can explain this, it would be very much useful for us rookies. Also, Any tips on identifying this sort of problems would be much appreciated. I used a naive algorithm to solve this problem and ended up solving only the smaller data set.(It took heck of a time to compile the larger data set which is required to be submitted within 8 minutes.). Thanks in advance.

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  • Java source code generation frameworks

    - by Superfilin
    I have a set of Java 5 source files with old-style Doclet tags, comments and annotations. And based on that I would like to write a generator for another set of Java classes. What is the best way to do that? And are there any good standalone libraries for code analysis/generation in Java? Any shared exprience in this field is appreciated. So, far I have found these: JaxME's Java Source Reflection - seems good, but it does not seem to support annotations. Also it had no release since 2006. Annogen - uses JDK's Doclet generator, which has some bugs under 1.5 JDK. Also it had no releases for a long time. Javaparser - seems good as well and pretty recent, but only supports Visitor pattern for a single class i.e. no query mechanism like in the 2 above packages.

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  • Practical Python-based visual programming environment?

    - by Who8MyLunch
    I am looking for a practical visual programming environment based on Python. My primary application is algorithm development for processing remote-sensing imagery. I was initially inspired by LabVIEW from National Instruments, but that is more geared towards laboratory measurements and simulations. I write a lot of prototype code in Python and do a lot of interactive analysis with IPython. Does there exist a visual framework where a "program" is represented by connected nodes which each read data, do some work, and output data to the next node? I would like to use Python to write the code residing in each node. So far the best I've seen is Orange http://www.ailab.si/orange/, but it does not have the ability to start/stop individual nodes.

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  • Is my TFS2010 backup/restore hosed?

    - by bwerks
    Hi all, I recently set up a sandbox TFS to test TFS-specific features without interfering with the production TFS. I was happy I did this sooner than I thought--I hadn't been backing up the encryption key from SSRS and upon restoring the reporting databases, they remained inactive, requiring initialization that could only come from applying the encryption key. Said encryption key was lost when I nuked the partition after backing up the TFS databases. The only option I seemed to have is to delete the encrypted data. I'm fine with this, since there wasn't much in there to begin with, however once they're deleted I'm not quite sure how to configure TFS to recognize a new installation of these services while using the restored versions of everything else. Unfortunately, the TFS help file doesn't seem to account for this state though. Is there a way to essentially rebuild the reporting and analysis databases? Or are they gone forever?

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  • R: including model specifications in xtable(anova(...))

    - by HamiltonUlmer
    Hello R comrades: I have a bunch of loglinear models, which, for our purposes will just be glm() objects called mx, my, mz. I want to get a nicely-formatted xtable of the analysis of deviance, so naturally I would want to perform xtable(anova(mx, my, mz, test = "Chisq")). The vanilla output of xtable, however, doesn't include the model specifications. I'd like to include those for all the ANOVA tests I'm running, so if there is not a param I'm missing that does this I'll probably just have to hack up my own solution. But looking over the help page, there doesn't seem to be an easy way to include the model specifications. Any thoughts? Alternatives? If it helps this was done in 2.9.1 with xtable 1.5-5.

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  • Simple and efficient distribution of C++/Boost source code (amalgamation)

    - by Arrieta
    Hello: My job mostly consists of engineering analysis, but I find myself distributing code more and more frequently among my colleagues. A big pain is that not every user is proficient in the intricacies of compiling source code, and I cannot distribute executables. I've been working with C++ using Boost, and the problem is that I cannot request every sysadmin of every network to install the libraries. Instead, I want to distribute a single source file (or as few as possible) so that the user can g++ source.c -o program. So, the question is: can you pack the Boost libraries with your code, and end up with a single file? I am talking about the Boost libraries which are "headers only" or "templates only". As an inspiration, please look at the distribution of SQlite or the Lemon Parser Generator; the author amalgamates the stuff into a single source file which is trivial to compile. Thank you.

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  • Random List of millions of elements in Python Efficiently

    - by eWizardII
    Hello, I have read this answer potentially as the best way to randomize a list of strings in Python. I'm just wondering then if that's the most efficient way to do it because I have a list of about 30 million elements via the following code: import json from sets import Set from random import shuffle a = [] for i in range(0,193): json_data = open("C:/Twitter/user/user_" + str(i) + ".json") data = json.load(json_data) for j in range(0,len(data)): a.append(data[j]['su']) new = list(Set(a)) print "Cleaned length is: " + str(len(new)) ## Take Cleaned List and Randomize it for Analysis shuffle(new) If there is a more efficient way to do it, I'd greatly appreciate any advice on how to do it. Thanks,

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  • How can I use splne() with ggplot?

    - by David
    I would like to fit my data using spline(y~x) but all of the examples that I can find use a spline with smoothing, e.g. lm(y~ns(x), df=_). I want to use spline() specifically because I am using this to do the analysis represented by the plot that I am making. Is there a simple way to use spline() in ggplot? I have considered the hackish approach of fitting a line using geom_smooth(aes(x=(spline(y~x)$x, y=spline(y~x)$y)) but I would prefer not to have to resort to this. Thanks!

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  • fortran error I/O

    - by jpcgandre
    I get this error when compiling: forrtl: severe (256): unformatted I/O to unit open for formatted transfers, unit 27, file C:\Abaqus_JOBS\w.txt The error occurs in the beginning of the analysis. At the start, the file w.txt is created but is empty. The error may be related to the fact that I want to read from an empty file. My code is: OPEN(27, FILE = "C:/Abaqus_JOBS/w.txt", status = "UNKNOWN") READ(27, *, iostat=stat) w IF (stat .NE. 0) CALL del_file(27, stat) SUBROUTINE del_file(uFile, stat) IMPLICIT NONE INTEGER uFile, stat C If the unit is not open, stat will be non-zero CLOSE(unit=uFile, status='delete', iostat=stat) END SUBROUTINE Ref: Close multiple files If you agree with my opion about the cause of the error, is there a way to solve it? Thanks

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  • RUP (Rational Unified Process)

    - by tony
    I have chosen to use the development method RUP (Rational Unified Process) in my project. This is a method I've never used before. I've also included some elements from Scrum in the development process. The question is what the requirement specifications should contain in a RUP-model? Is it functional and non-functional requirements? And what should be included in a technical analysis and security requirements for RUP? Can’t find any information. Notes about this would be helpful. Hope people with RUP experience can share some useful experiences

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  • Excel - check if row contains ANY value *more than once*

    - by user2536778
    I am doing data analysis and sometimes I need to check and to make sure each row in excel does not have any repeated value. I hope that there is a formula where each time if there's a repeated value in the same row, the value will be highlighted and it doesn't matter what value it is, as long as it's repeated in the same row. I try to search it everywhere but the closest I can find is below question & answer ( which couldn't apply to me as I need a formula that can highlight any value that's repeated and not only zero): I have rows which contain grades for students (numerical values), where the number 0 means they missed a class. I want the row to be highlighted in one color if they have "0" 3 or 4 times, and in another color if they have "0" 5 times or more. =COUNTIF(1:1,0)=5 Anyone can help me? Thanks in advance!

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  • Reference-counted object is used after it is released

    - by EndyVelvet
    Doing code analysis of the project and get the message "Reference-counted object is used after it is released" on the line [defaults setObject: deviceUuid forKey: @ "deviceUuid"]; I watched this topic Obj-C, Reference-counted object is used after it is released? But the solution is not found. ARC disabled. // Get the users Device Model, Display Name, Unique ID, Token & Version Number UIDevice *dev = [UIDevice currentDevice]; NSString *deviceUuid; if ([dev respondsToSelector:@selector(uniqueIdentifier)]) deviceUuid = dev.uniqueIdentifier; else { NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults]; id uuid = [defaults objectForKey:@"deviceUuid"]; if (uuid) deviceUuid = (NSString *)uuid; else { CFStringRef cfUuid = CFUUIDCreateString(NULL, CFUUIDCreate(NULL)); deviceUuid = (NSString *)cfUuid; CFRelease(cfUuid); [defaults setObject:deviceUuid forKey:@"deviceUuid"]; } } Please help find the cause.

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