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  • How do I find out if the variable is declared in Python?

    - by golergka
    I want to use a module as a singleton referenced in other modules. It looks something like this (that's not actually a code I'm working on, but I simplified it to throw away all unrelated stuff): main.py import singleton import printer def main(): singleton.Init(1,2) printer.Print() if __name__ == '__main__': pass singleton.py variable1 = '' variable2 = '' def Init(var1, var2) variable1 = var1 variable2 = var2 printer.py import singleton def Print() print singleton.variable1 print singleton.variable2 I expect to get output 1/2, but instead get empty space. I understand that after I imported singleton to the print.py module the variables got initialized again. So I think that I must check if they were intialized before in singleton.py: if not (variable1): variable1 = '' if not (variable2) variable2 = '' But I don't know how to do that. Or there is a better way to use singleton modules in python that I'm not aware of :)

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  • How do I create efficient instance variable mutators in Matlab?

    - by Trent B
    Previously, I implemented mutators as follows, however it ran spectacularly slowly on a recursive OO algorithm I'm working on, and I suspected it may have been because I was duplicating objects on every function call... is this correct? %% Example Only obj2 = tripleAllPoints(obj1) obj.pts = obj.pts * 3; obj2 = obj1 end I then tried implementing mutators without using the output object... however, it appears that in MATLAB i can't do this - the changes won't "stick" because of a scope issue? %% Example Only tripleAllPoints(obj1) obj1.pts = obj1.pts * 3; end For application purposes, an extremely simplified version of my code (which uses OO and recursion) is below. classdef myslice properties pts % array of pts nROW % number of rows nDIM % number of dimensions subs % sub-slices end % end properties methods function calcSubs(obj) obj.subs = cell(1,obj.nROW); for i=1:obj.nROW obj.subs{i} = myslice; obj.subs{i}.pts = obj.pts(1:i,2:end); end end function vol = calcVol(obj) if obj.nROW == 1 obj.volume = prod(obj.pts); else obj.volume = 0; calcSubs(obj); for i=1:obj.nROW obj.volume = obj.volume + calcVol(obj.subs{i}); end end end end % end methods end % end classdef

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  • How do I test if a variable is a number in bash?

    - by Flávio Amieiro
    I just can't figure out how do I make sure an argument passed to my script is a number or not. All I want to do is something like this: test *isnumber* $1 && VAR=$1 || echo "need a number" Any help? UPDATE: I managed (whit Charles' help) to do it, but I'm not yet sure it's the best way to do that (even though it worked on my tests). This is how it ended up: [[ $1 =~ "^[0-9]+$" ]] && echo "numero" && exit 0 || echo "nao numero" && exit 1

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  • How do I get user input to refer to a variable in Python?

    - by somefreakingguy
    I would like to get user input to refer to some list in my code. I think it's called namespace? So, what would I have to do to this code for me to print whatever the user inputs, supposing they input 'list1' or 'list2'? list1 = ['cat', 'dog', 'juice'] list2 = ['skunk', 'bats', 'pogo stick'] x = raw_input('which list would you like me to print?') I plan to have many such lists, so a series of if...then statements seems unruly.

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  • is an instance variable in an action of a controller available for all the controllers view?

    - by fenec
    I am just trying to printout the parameters that have been entered into my form. basically i create a new bet then i display the parameters: MIGRATION enter code here class CreateBets < ActiveRecord::Migration def self.up create_table :bets do |t| t.integer :accepted ,:default = 0 t.integer :user_1_id #proposer t.integer :user_2_id #receiver t.integer :team_1_id #proposer's team t.integer :team_2_id #receiver's team t.integer :game_id t.integer :winner t.integer :amount t.timestamps end end def self.down drop_table :bets end end CONTROLLER bets_controller.erb enter code here class BetsController < ApplicationController def index redirect_to new_bet_path end def new @b=Bet.new end def create @@points=params[:points] @@winner=params[:winner] end end VIEWS New.erb New Bet <% facebook_form_for Bet.new do |f| %> <%= f.text_field :amount, :label=>"points" %> <%= f.text_field :winner, :label=>"WinningTeam" %> <%= f.buttons "Bet" %> <% end %> create.erb enter code here points:<%= @@points %> <br> winner:<%= @@winner %>

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  • How can I alter an external variable from inside my AJAX?

    - by tmedge
    I keep on having these same two problems. I have been trying to use Remy Sharp's wonderful tagSuggest plugin, and it works great. Until I try to use an AJAX call to get tags from my database. My setGlobalTags() works great, with my defined myTagList at the top of the function. What I want to do is set myTagList equal to the result from my AJAX. My problem is that I can neither call setGlobalTags() from inside my success or error functions, nor actually alter the original myTagList. Also, I keep on having this other issue as well. I keep this code in my Master page, and my AJAX returns 'success' on almost every page. I only (and always) get the error alert when I navigate to a page that actually contains something of id="ParentTags". I don't see why this is happening, because my $('#ParentTags').tagSuggest(); is definitely after my AJAX call. I realize that this is probably just some dumb conventions error, but I am new to this and I'm here to learn from you guys. Thanks in advance! $(function() { var myTagList = ['test', 'testMore', 'testALot']; $.ajax({ type: "POST", url: 'Admin/GetTagList', dataType: 'json', success: function(resultTags) { myTagList = resultTags; alert(myTagList[0]); setGlobalTags(myTagList); }, error: function() { alert('Error'); setGlobalTags(myTagList); } }); setGlobalTags(myTagList); $('#ParentTags').tagSuggest(); });

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  • What's the environment variable for the path to the desktop?

    - by Scott Langham
    I'm writing a Windows batch file and want to copy something to the desktop. I think I can use this: %UserProfile%\Desktop\ However, I'm thinking, that's probably only going to work on an English OS. Is there a way I can do this in a batch file that will work on any internationalized version? UPDATE I tried the following batch file: REG QUERY "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders" /v Desktop FOR /F "usebackq tokens=3 skip=4" %%i in (`REG QUERY "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders" /v Desktop`) DO SET DESKTOPDIR=%%i FOR /F "usebackq delims=" %%i in (`ECHO %DESKTOPDIR%`) DO SET DESKTOPDIR=%%i ECHO %DESKTOPDIR% And got this output: S:\REG QUERY "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders" /v Desktop HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders Desktop REG_EXPAND_SZ %USERPROFILE%\Desktop S:\FOR /F "usebackq tokens=3 skip=4" %i in (`REG QUERY "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folder s" /v Desktop`) DO SET DESKTOPDIR=%i S:\FOR /F "usebackq delims=" %i in (`ECHO ECHO is on.`) DO SET DESKTOPDIR=%i S:\SET DESKTOPDIR=ECHO is on. S:\ECHO ECHO is on. ECHO is on.

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  • Creating a variable-speed slideshow based on USB input on OSX.

    - by Dave A
    I have a friend who is trying to put together a geeky little contraption for a wedding, where people can view a slideshow. Neither of us use Macs, nor have programmed for one, but for various reasons it has to run on a Mac. There will be a USB ammeter hooked up to a bike dynamo. What we want is for a slideshow to be run, and advance at a speed relative to how fast someone is pedaling on a stationary bike. After much googling, it seems like we could load an iPhoto slideshow up via applescript. Is it possible to pause the slideshow and advance it with keypress commands? The applescript commands would be run via a bash script or similar that would monitor the value returned by the USB ammeter's command-line app and issue the keypress events accordingly. Is there some other app that could be likewise scripted to display photos?Hoping someone has some hints to get us started in the right direction! Thanks!

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  • R Question. Numeric variable vs. Non-numeric and "names" function

    - by Michael
    > scores=cbind(UNCA.score, A.score, B.score, U.m.A, U.m.B) > names(scores)=c('UNCA.scores', 'A.scores', 'B.scores','UNCA.minus.A', 'UNCA.minus.B') > names(scores) [1] "UNCA.scores" "A.scores" "B.scores" "UNCA.minus.A" "UNCA.minus.B" > summary(UNCA.scores) X6.69230769230769 Min. : 4.154 1st Qu.: 7.333 Median : 8.308 Mean : 8.451 3rd Qu.: 9.538 Max. :12.000 > is.numeric(UNCA.scores) [1] FALSE > is.numeric(scores[,1]) [1] TRUE My question is, what is the difference between UNCA.scores and scores[,1]? UNCA.scores is the first column in the data.frame 'scores', but they are not the same thing, since one is numeric and the other isn't. If UNCA.scores is just a label here how can I make it be equivalent to 'scores[,1]? Thanks!

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  • Why do condition variables sometimes erroneously wake up?

    - by aspo
    I've known for eons that the way you use a condition variable is lock while not task_done wait on condition variable unlock Because sometimes condition variables will spontaneously wake. But I've never understood why that's the case. In the past I've read it's expensive to make a condition variable that doesn't have that behavior, but nothing more than that. So... why do you need to worry about falsely being woken up when waiting on a condition variable?

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  • Manipulating the address of a variable to store a smaller type?

    - by Sidnicious
    This is what I get for pampering myself with high-level programming languages. I have a function which writes a 32-bit value to a buffer, and a uint64_t on the stack. Is the following code a sane way to store it? uint64_t size = 0; // ... getBytes((uint32_t*)&size+0x1); I'm assuming that this would be the canonical, safe style: uint64_t size = 0; // ... uint32_t smallSize; getBytes(&smallSize); size = smallSize;

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  • How can I pass a const array or a variable array to a function in C?

    - by CSharperWithJava
    I have a simple function Bar that uses a set of values from a data set that is passed in in the form of an Array of data structures. The data can come from two sources: a constant initialized array of default values, or a dynamically updated cache. The calling function determines which data is used and should be passed to Bar. Bar doesn't need to edit any of the data and in fact should never do so. How should I declare Bar's data parameter so that I can provide data from either set? union Foo { long _long; int _int; } static const Foo DEFAULTS[8] = {1,10,100,1000,10000,100000,1000000,10000000}; static Foo Cache[8] = {0}; void Bar(Foo* dataSet, int len);//example function prototype Note, this is C, NOT C++ if that makes a difference; Edit Oh, one more thing. When I use the example prototype I get a type qualifier mismatch warning, (because I'm passing a mutable reference to a const array?). What do I have to change for that?

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  • How do I get Mathematica to thread a 2-variable function over two lists, using functional programmin

    - by Leah Wrenn Berman
    Lets say I have a function f[x_, y_], and two lists l1, l2. I'd like to evaluate f[x,y] where x runs over the list l1 and y runs over the list l2, and I'd like to do it without having to make all pairs of the form {l1[[i]],l2[[j]]}. (Motivation: I'm trying to implement some basic Haskell programs in Mathematica. In particular, I'd like to be able to code the Haskell program isMatroid::[[Int]]->Bool isMatroid b =and[or[sort(union(xs\\[x])[y]'elem'b|y<-ys]|xs<-b,ys<-b, xs<-x] I think I can do the rest of it, if I can figure out the original question, but I'd like the code to be Haskell-like. Any suggestions for implementing Haskell-like code in Mathematica would be appreciated.)

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  • How can I access a JavaScript variable value in JSP?

    - by Pramod
    function modification() { alert(document.getElementById("record").value); var rec=document.getElementById("record").value; <% Connection connect = DriverManager.getConnection("jdbc:odbc:DSN","scott","tiger"); Statement stm=connect.createStatement(); String record=""; // I want value of "rec" here. ResultSet rstmt=stm.executeQuery("select * from "+record); %> }

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  • How to set a property of a C# 4 dynamic object when you have the name in another variable

    - by Kieran Benton
    I'm looking for a way to modify properties on a dynamic C# 4.0 object with the name of the property known only at runtime. Is there a way to do something like (ExpandoObject is just used as an example, this could be any class that implements IDynamicMetaObjectProvider): string key = "TestKey"; dynamic e = new ExpandoObject(); e[key] = "value"; Which would be equivalent to: dynamic e = new ExpandoObject(); e.TestKey = "value"; Or is the only way forward reflection?

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  • How can you pre-define a variable that will contain an anonymous type?

    - by HitLikeAHammer
    In the simplified example below I want to define result before it is assinged. The linq queries below return lists of anonymous types. result will come out of the linq queries as an IEnumerable<'a but I can't define it that way at the top of the method. Is what I am trying to do possible (in .NET 4)? bool large = true; var result = new IEnumerable(); //This is wrong List<int> numbers = new int[]{1,2,3,4,5,6,7,8,9,10}.ToList<int>(); if (large) { result = from n in numbers where n > 5 select new { value = n }; } else { result = from n in numbers where n < 5 select new { value = n }; } foreach (var num in result) { Console.WriteLine(num.value); } EDIT: To be clear I know that I do not need anonymous types in the example above. It is just to illustrate my question with a small, simple example.

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  • How do I maximize a function in Mathematica which takes in a variable length list as input?

    - by Mike
    I have a time-series like function which gives an output based on a list of real numbers(i.e. you can run the function on a list of 1,2,3,... real numbers). The issue I'm encountering is how to maximize the function for a given list length(subject to a set of constraints). I could fix the function to a fixed number of real numbers(i.e. f [x_Real, y_Real] instead of f[x_List]) and treat x and y as the first two elements of the list, and call Maximize on the function, but this is not really elegant. I want to be able to easily change the number of elements in the list. What is the best way to optimize a function like I described, which takes a list as an argument, for a fixed list length?

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