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• Can you explain what's going on in this Ruby code?

  - by samoz

  I'm trying to learn Ruby as well as Ruby on Rails right now. I'm following along with Learning Rails, 1st edition, but I'm having a hard time understanding some of the code. I generally do work in C, C++, or Java, so Ruby is a pretty big change for me. I'm currently stumped with the following block of code for a database migrator: def self.up create_table :entries do |t| t.string :name t.timestamps end end Where is the t variable coming from? What does it actually represent? Is it sort of like the 'i' in a for(i=0;i<5;i++) statement? Also, where is the :entries being defined at? (entries is the name of my controller, but how does this function know about that?)

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• Matlab: Randomize and Split

  - by Null-Hypothesis

  I have following data matrix in Matlab, I am trying to actually split this into multiple segments by passing a variable to a matlab function. But before splitting I would like to shuffle the matrix. The size of my matrix is 150X4 s.data 5.1000 3.5000 1.4000 0.2000 4.9000 3.0000 1.4000 0.2000 4.7000 3.2000 1.3000 0.2000 4.6000 3.1000 1.5000 0.2000 5.0000 3.6000 1.4000 0.2000 .. s = data: [150x4 double] labels: [150x1 double] Coming from R environment I find MatLab is very strange. Initially I thought the columns in matrix has a relationshop like in a R dataframe but thats wrong in my assumption.

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• Kohana -- Command Line

  - by swt83

  I'm trying to "faux-fork" a process (an email being sent via SMTP) in my web application, and the application is built on Kohana. $command = 'test/email'; exec('php index.php '.$command.' > /dev/null/ &', $errors, $response); I'm getting an error -- Notice: Undefined index: SERVER_NAME When I look into Kohana's index.php file, I see that it is looking for a variable named SERVER_NAME, but I guess it is coming up NULL because Kohana couldn't detect this value and set it prior to run. Any ideas how to get Kohana to run via command line?

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• AS3 Memory management when instantiating extended classes

  - by araid

  I'm developing an AS3 application which has some memory leaks I can't find, so I'd like to ask some newbie questions about memory management. Imagine I have a class named BaseClass, and some classes that extend this one, such as ClassA, ClassB, etc. I declare a variable: myBaseClass:BaseClass = new ClassA(); After a while, I use it to instantiate a new object: myBaseClass = new ClassB(); some time after myBaseClass = new ClassC(); and the same thing keeps happening every x millis, triggered by a timer. Is there any memory problem here? Are the unused instances correctly deleted by the garbage collector? Thanks!

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• Return popupmenu selection in MATLAB using one line of code

  - by Doresoom

  I have a GUI which uses a selection from a popupmenu in another callback. Is there a way to return the selected value of the popupmenu in only one line without creating any temporary variables? I've tried several solutions, but I've only managed two lines with one temporary variable: Three lines: list=get(handles.popupmenu1,'String'); val=get(handles.popupmenu1,'Value'); str=list{val}; Two lines: temp=get(handles.popupmenu1,{'String','Value'}); str=temp{1}{temp{2}}; Can anyone shave it down to one? PS, It's a dynamic menu, so I can't just use get(handles.popupmenu1,'Value') and ignore the string component altogether.)

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• android: Check if a View is bringed to front

  - by user329692

  Hi Guys! I made a custom component which simple extends a WebView This component is used into activities that are loaded from a tabhost. This component creates a timertask too. I'd like to execute the task only if the activity that contains the component is visible. Ex: public class MyWebView extends WebView { public MyWebView(Context context, AttributeSet as) { super(context,as); /** More code **/ TimerTask ttask = new TimerTask() { @Override public void run() { if (iamvisible) doStuff(); } }; timer = new Timer(); timer.schedule(ttask, refreshInterval * 1000, refreshInterval * 1000); } } How can I set the iamvisible variable? I tried overriding onWindowFocusChanged and onWindowVisibilityChanged but with no luck Regards in advance

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• filtering elements from list of lists in Python?

  - by user248237

  I want to filter elements from a list of lists, and iterate over the elements of each element using a lambda. For example, given the list: a = [[1,2,3],[4,5,6]] suppose that I want to keep only elements where the sum of the list is greater than N. I tried writing: filter(lambda x, y, z: x + y + z >= N, a) but I get the error: <lambda>() takes exactly 3 arguments (1 given) How can I iterate while assigning values of each element to x, y, and z? Something like zip, but for arbitrarily long lists. thanks, p.s. I know I can write this using: filter(lambda x: sum(x)..., a) but that's not the point, imagine that these were not numbers but arbitrary elements and I wanted to assign their values to variable names.

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• How to put/get INT to/from a WCHAR array ?

  - by nimo

  how can I put a INT type variable to a wchar array ? Thanks EDIT: Sorry for the short question. Yes we can cast INT to a WCHAR array using WCHAR*, but when we are retrieving back the result (WCHAR[] to INT), I just realize that we need to read size of 2 from WCHAR array since INT is 4 BYTEs which is equal to 2 WCHARs. WCHAR arData[20]; INT iVal = 0; wmemcpy((WCHAR*)&iVal, arData, (sizeof(INT))/2); Is this the safest way to retrieve back INT value from WCHAR array

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• About the fix for the interference between Company mode and Yasnippet

  - by janoChen

  Emacs wiki says: Company does interfere with Yasnippet’s native behaviour. Here’s a quick fix: http://gist.github.com/265010 The code is the following: (define-key company-active-map "\t" 'company-yasnippet-or-completion) (defun company-yasnippet-or-completion () (interactive) (if (yas/expansion-at-point) (progn (company-abort) (yas/expand)) (company-complete-common))) (defun yas/expansion-at-point () "Tested with v0.6.1. Extracted from `yas/expand-1'" (first (yas/current-key))) I placed that code in my .emacs and the following message appeared: Warning (initialization): An error occurred while loading `c:/Documents and Settings/Alex.AUTOINSTALL.001/Application Data/.emacs.elc': Symbol's value as variable is void: company-active-map To ensure normal operation, you should investigate and remove the cause of the error in your initialization file. Start Emacs with the `--debug-init' option to view a complete error backtrace. Do I have to place the fix code inside a YASnippet's .el file? or in my .emacs (which throws me an error)?

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• a simple secenerio to implement java script asp.net C#, question rephrased

  - by user287745

  i had asked this question before but got no answer correct. so, this is a simple thing textbox.text='user typing'; button:-store the value to a variable and a database. very simple nothing to it but there should be no post back, that is the page must not load again, try ajax? tried it not working i must a lot of time trying to implement this using java script ajax and read many many post, but for some reason i cannot implement the functionality correctly. please help. thank you

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• how to use expressons as function parameters in powershell

  - by rmeador

  This is a very simple task in every language I have ever used, but I can't seem to figure it out in PowerShell. An example of what I'm talking about in C: abs(x + y) The expression x + y is evaluated, and the result passed to abs as the parameter... how do I do that in PowerShell? The only way I have figured out so far is to create a temporary variable to store the result of the expression, and pass that. PowerShell seems to have very strange grammar and parsing rules that are constantly catching me by surprise, just like this situation. Does anyone know of documentation or a tutorial that explains the basic underlying theory of the language? I can't believe these are all special cases, there must be some rhyme or reason that no tutorial I have yet read explains. And yes, I've read this question, and all of those tutorials are awful. I've pretty much been relegated to learning from existing code.

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• Documenting preprocessor defines in Doxygen

  - by Fire Lancer

  Is it possible to document preprocessor defines in Doxygen? I expected to be able to do it just like a variable or function, however the Doxygen output appears to have "lost" the documentation for the define, and does not contain the define its self either. I tried the following /**My Preprocessor Macro.*/ #define TEST_DEFINE(x) (x*x) and /**@def TEST_DEFINE My Preprocessor Macro. */ #define TEST_DEFINE(x) (x*x) I also tried putting them within a group (tried defgroup, addtogroup and ingroup) rather than just at the "file scope" however that had no effect either (although other items in the group were documented as intended). I looked through the various Doxygen options, but couldn't see anything that would enable (or prevent) the documentation of defines.

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• Float multiple fixed-width / varible-height boxes into 2 columns

  - by Jeremy H

  I'll try to explain this as best I can. I have multiple divs that are fixed-width but variable height. I want to float these boxes into two columns inside a fixed-width container. What happens when a give them all a float: left value, I get something like this: ######### ######### # box 1 # # box 2 # ######### # ..... # ......... # ..... # ......... ######### ######### ######### # box 3 # # box 4 # # ..... # # ..... # ######### ######### ######### ######### # box 5 # # box 6 # # ..... # ######### # ..... # ######### (The periods are white space) What I really would really like is the top of box 3 to touch the bottom of box 1. Any easy way to acheive this?

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• R: how can I concatenate a list?

  - by John

  I'm trying to produce a single variable which is a concatenation of two chars e.g to go from "p30s4" "p28s4" to "p30s4 p28s4". I've tried cat and paste as shown below. Both return empty variables. What am I doing wrong? > blah = c("p30s4","p28s4") > blah [1] "p30s4" "p28s4" > foo = cat(blah) p30s4 p28s4 > foo NULL > foo = paste(cat(blah)) p30s4 p28s4 > foo character(0)

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• asp.net regex to find anchor tags and replace their url

  - by ace

  Hi -i'm trying to find all the anchor tags and appending the href value with a variable. for example <a href="/page.aspx">link</a> will become <a href="/page.aspx?id=2"> <A hRef='http://www.google.com'><img src='pic.jpg'></a> will become <A hRef='http://www.google.com?id=2'><img src='pic.jpg'></a> I'm able to match all the anchor tags and href values using regex, then i manually replace the values using string.replace, however i dont think its the efficient way to do this. Is there a solution where i can use something like regex.replace(html,newurlvalue)

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• XQuery fn:replace not behaving as expected

  - by CoolGravatar

  I have an Excel worksheet in XML format which contains <Cell ss:StyleID="s127"><Data ss:Type="String">A01-Replace</Data></Cell> I want to replace @A01-Replace with a different string. I'm using the XQuery's replace function like so: let $excel := doc("excel.xml") let $test := "another string" return replace($excel, "(A[0-9]+-Replace)", $test) Before calling replace, the variable $excel is valid XML upon output. However, when I output $excel after I call the replace function, all of the XML tags have been stripped, and $excel is a string with the content of the cells as its values. I would like to keep the XML tags there. Any ideas?

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• How to increment a value using a C-Preprocessor in Objective-C?

  - by mystify

  Example: I try to do this: static NSInteger stepNum = 1; #define METHODNAME(i) -(void)step##i #define STEP METHODNAME(stepNum++) @implementation Test STEP { // do stuff... [self nextFrame:@selector(step2) afterDelay:1]; } STEP { // do stuff... [self nextFrame:@selector(step3) afterDelay:1]; } STEP { // do stuff... [self nextFrame:@selector(step4) afterDelay:1]; } // ... When building, Xcode complains that it can't increment stepNum. This seems logical to me, because at this time the code is not "alive" and this pre-processing substitution stuff happens before actually compiling the source code. Is there another way I could have an variable be incremented on every usage of STEP macro, the easy way?

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• Build Path issue with Java Android project when starting Eclipse

  - by Matt Smith

  I booted up eclipse to start on a project, and without typing in a word I already have several errors. package department.namespace; import android.app.Activity; import android.os.Bundle; public class DepartmentActivity extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } } At package department.namespace, it says: multiple marks at this line and the type java.lang.Object cannot be resolved. It is indirectly referenced from required .class files The import android.os cannot be resolved. Override cannot be resolved as a type The method OnCreate(Bundle) is undefined for the type Activity R. cannot be resolved as a variable. Since this JUST came up when I started Eclipse, how do I fix this?

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• How to skip extra lines before the header of a tab delimited delimited file in R

  - by Michael Dunn

  The software I am using produces log files with a variable number of lines of summary information followed by lots of tab delimited data. I am trying to write a function that will read the data from these log files into a data frame ignoring the summary information. The summary information never contains a tab, so the following function works: read.parameters <- function(file.name, ...){ lines <- scan("tmp.log", what="character", sep="\n") first.line <- min(grep("\\t", lines)) return(read.delim(file.name, skip=first.line-1, ...)) } However, these logfiles are quite big, and so reading the file twice is very slow. Surely there is a better way?

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• AS3 Accessing Variables of Parent Class From Child

  - by TheDarkIn1978

  i'm trying to assign a parent's variable from the parent's child //Parent public class Main extends Sprite { public var selectedSquare:Sprite; public function Main() { //inits and adds new Square child class to display list } ... ------- //Child public function dragSquare(evt:MouseEvent):void { Sprite(parent).selectedSquare = this; //evil doesn't work! parent.addChild(this); this.startDrag(); } i'm receiving this error, but i'm casting parent from displayObjectContainer to a Sprite so i have no idea why it's not working. 1119: Access of possibly undefined property selectedSquare through a reference with static type flash.display:Sprite.

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• How to build third party libraries with Android NDK

  - by heiko.witte

  How can I compile third party libraries with the android NDK? I am compiling a wrapper which implements the JNI functions as a shared lib, which depends on another 3rd party lib (HTK). I don't know how to setup the makefile. The following does not work: LOCAL_PATH := $(call my-dir) include $(CLEAR_VARS) include HTKLib/Android.mk LOCAL_PATH := $(call my-dir) include $(CLEAR_VARS) LOCAL_MODULE := gaitfuncs LOCAL_SRC_FILES := gaitfuncs.c %LOCAL_LDLIBS := -L$(SYSROOT)/usr/lib -llog include $(BUILD_SHARED_LIBRARY) The second makefile should then build a static lib which my shared lib links to. How can I include this subdir makefile properly? Is this the correct way of doing it? And as a bonus: Are there wildcards for the LOCAL_SRC_FILES variable to take all files ending in .c for example. Thanks!

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• When to pass by value?

  - by Dervin Thunk

  Dear all. I was wondering if there are examples of situations where you would purposefully pass an argument by value in C. Let me rephrase. When do you purposefully use C's pass-by-value for large objects? Or, when do you care that the object argument is fully copied in a local variable? EDIT: Now that I think about it, if you can avoid pointers, then do. Nowadays, "deep" copying is possible for mostly everything in small apps, and shallow copying is more prone to pointer bugs. Maybe.

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• How do I create multiple submit buttons for the same form in Rails?

  - by Angela

  I need to have multiple submit buttons. I have a form which creates an instance of Contact_Call. One button creates it as normal. The other button creates it but needs to have a different :attribute value from the default, and it also needs to set the attribute on a different, but related model used in the controller. How do I do that? I can't change the route, so is there a way to send a different variable that gets picked up by [:params]? And if I do then, what do I do in the controller, set up a case statement?

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• using subset but old variables still left

  - by user2520852

  I am working with a data set, which is basically daily usage data (let's just say variable X and Y) by different cities (about 150 cities). I have created a subset of data for only specific cities, choosing just 3 of the 150 cities. Then when I do tapply by cities, I get means for 3 cities but also get NA for all other 147 cities that was in the data set. I am using the below coding df<-read.csv(...) df_sub<-subset(df,df$City==1|df$City==3|df$City==19) X_Breakdown<-tapply(X,df_sub$City, mean, na.rm=TRUE) Print(X_Breakdown) City 1 City 2 15 NA City 3 City 4 12 NA City 5 City 6 NA NA Hope you get the idea. I would like to get a dataset that only contains the 3 cities that I'm interested in. It seems that the set of variables is encoded in R, is there a way to fix this? Kindly advise. Thanks

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• ASP.NET C# Application Object Getters and Setters

  - by kellax

  I have had a hard time finiding a newbie friendly example of accessing Application Object. I have few things ( arrays ) i would like to store in Application Object to keep as persistant data for about 2h till AppRecycle Anyhow i know how to set an Application Object variable this way: // One way String[] users = new String[1000]; Application["users"] = users; // Another way Application.Add("users", users); However i do not know how to access these variables once in Application Object there is a Getter method Get however it requires int index and other one Contents which get's everything. Here i try to retrive my String[] array but gives me a error that i am trying to convert Object to String. String[] usersTable = Application["users"]; // Since this is an object i also tried Application.users but gives error

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