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  • List in a Python class shares the same object over 2 different instances?

    - by zfranciscus
    I created a class: class A: aList = [] now I have function that instantiate this class and add items into the aList. note: there are 2 items for item in items: a = A(); a.aList.append(item); I find that the first A and the second A object has the same number of items in their aList. I would expect that the first A object will have the first item in its list and the second A object will have the second item in its aList. Can anyone explain how this happens ? PS: I manage to solve this problem by moving the aList inside a constructor : def __init__(self): self.aList = []; but I am still curious about this behavior

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  • MySQL::Eliminating redundant elements from a table?

    - by Legend
    I have a table like this: +-------+---------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+---------+------+-----+---------+-------+ | v1 | int(11) | YES | MUL | NULL | | | v2 | int(11) | YES | MUL | NULL | | +-------+---------+------+-----+---------+-------+ There is a tremendous amount of duplication in this table. For instance, elements like the following: +------+------+ | v1 | v2 | +------+------+ | 1 | 2 | | 1 | 3 | | 1 | 4 | | 1 | 5 | | 1 | 6 | | 1 | 7 | | 1 | 8 | | 1 | 9 | | 2 | 1 | | 4 | 1 | | 5 | 1 | | 6 | 1 | | 7 | 1 | | 8 | 1 | | 9 | 1 | +------+------+ The table is large with 1540000 entries. To remove the redundant entries (i.e. to get a table having only (1,9) and no (9,1) entries), I was thinking of doing it with a subquery but is there a better way of doing this?

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  • Declaring an integer Range with step != 1 in Ruby

    - by Dan Tao
    Hey guys, I'm completely new to Ruby, so be gentle. Say I want to iterate over the range of even numbers from 2 to 100; how would I do that? Obviously I could do: (2..100).each do |x| if x % 2 == 0 # my code end end But, obviously (again), that would be pretty stupid. I know I could do something like: i = 2 while i <= 100 # my code i += 2 end I believe I could also write my own custom class that provides its own each method (?). I am almost sure that would be overkill, though. I'm interested in two things: Is it possible to do this with some variation of the standard Range syntax (i.e., (x..y).each)? Either way, what would be the most idiomatic "Ruby way" of accomplishing this (using a Range or otherwise)? Like I said, I'm new to the language; so any guidance you can offer on how to do things in a more typical Ruby style would be much appreciated.

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  • How to pass objects to functions in C++?

    - by Rakesh K
    I am new to C++ programming, but I have experience in Java. I need guidance on how to pass objects to functions in C++. Do I need to pass pointers, references, or non-pointer and non-reference values? I remember in Java there are no such issues since we pass just the variable that holds reference to the objects. It would be great if you could also explain where to use each of those options.

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  • Unix: cannot add "\\ \n" even with escaping to the end of line

    - by HH
    I try to convert clean columnwise data to tables in tex. I am unable to have "\ \n" at each end of line. Please, see the command at the end. Data $ echo `. ./bin/addTableTexTags.sh < .data_3` 10.31 & 8.50 & 7.40 10.34 & 8.53 & 7.81 8.22 & 8.62 & 7.78 10.16 & 8.53 & 7.44 10.41 & 8.38 & 7.63 10.38 & 8.57 & 8.03 10.13 & 8.66 & 7.41 8.50 & 8.60 & 7.15 10.41 & 8.63 & 7.21 8.53 & 8.53 & 7.12 $ cat .data_3 10.31 8.50 7.40 10.34 8.53 7.81 8.22 8.62 7.78 10.16 8.53 7.44 10.41 8.38 7.63 10.38 8.57 8.03 10.13 8.66 7.41 8.50 8.60 7.15 10.41 8.63 7.21 8.53 8.53 7.12 addTableTexTags.sh #!/bin/bash sed -e "s@[[:space:]]@\t\&\t@g" -e "s@[[:space:]]*&*[[:space:]]*\$@\t \\ \\\\n@g" // Tried Escaping "\\" with "/" here and there // but cannot get a line ending with "\\ \n".

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  • Python - Removing duplicates from a string

    - by Daniel
    def remove_duplicates(strng): """ Returns a string which is the same as the argument except only the first occurrence of each letter is present. Upper and lower case letters are treated as different. Only duplicate letters are removed, other characters such as spaces or numbers are not changed. >>> remove_duplicates('apple') 'aple' >>> remove_duplicates('Mississippi') 'Misp' >>> remove_duplicates('The quick brown fox jumps over the lazy dog') 'The quick brown fx jmps v t lazy dg' >>> remove_duplicates('121 balloons 2 u') '121 balons 2 u' """ s = strng.split() return strng.replace(s[0],"") Writing a function to get rid of duplicate letters but so far have been playing around for an hour and can't get anything. Help would be appreciated, thanks.

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  • How to provide global functionality in multi-user database app

    - by Mike B
    I have been building a multi-user database application (in C#/WPF 4.0) that manages tasks for all employees of a company. I now need to add some functionality such as sending an email reminder to someone when a critical task is due. How should this be done? Obviously I don’t want every instance of the program to be performing this function (Heh each user would get 10+ emails). Should I add the capability to the application as a "Mode" and then run a copy on the database server in this mode or would it be better to create a new app altogether to perform "Global" type tasks? Is there a better way?

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  • Java queue and multi-dimension array

    - by javaLearner.java
    First of all, this is my code (just started learning java): Queue<String> qe = new LinkedList<String>(); qe.add("b"); qe.add("a"); qe.add("c"); qe.add("d"); qe.add("e"); My question: Is it possible to add element to the queue with two values, like: qe.add("a","1"); // where 1 is integer So, that I know element "a" have value 1. If I want to add a number let say "2" to element a, I will have like a = 3. If this cant be done, what else in java classes that can handle this? I tried to use multi-dimention array, but its kinda hard to do the queue, like pop, push etc. (Maybe I am wrong) How to call specific element in the queue? Like, call element a, to check its value. [Note] Please don't give me links that ask me to read java docs. I was reading, and I still dont get it. The reason why I ask here is because, I know I can find the answer faster and easier.

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  • How to get unique value in jquery?

    - by jquerier
    I am learning jquery. I have following chunk of code in a html file: <table width="100%"> <tr> <td align='center'> <div> <a id='get_this' href='#'> <input type='hidden' id='id' value='1'><img src='images/1.gif'></a> </div> </td> <td align='center'> <div> <a id='get_this' href='#'> <input type='hidden' id='id' value='2'><img src='images/2.gif'></a> </div> </td> <td align='center'> <div> <a id='get_this' href='#'> <input type='hidden' id='id' value='3'><img src='images/3.gif'></a> </div> </td> </tr> What I want to do is, when I click any of the image, I can get the value, so that I can display the information. For example, I click the id=1, then I will display information on id1 in somewhere else. I tried this: $("a#get_this").click(function(){ var id = $('input[type=hidden]#id').val(); window.alert("You have chosen the id: " + id); }); It always return id: 1 to me.

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  • Exceptions confusion

    - by Misiur
    Hi there. I'm trying to build site using OOP in PHP. Everyone is talking about Singleton, hermetization, MVC, and using exceptions. So I've tried to do it like this: Class building whole site: class Core { public $is_core; public $theme; private $db; public $language; private $info; static private $instance; public function __construct($lang = 'eng', $theme = 'default') { if(!self::$instance) { try { $this->db = new sdb(DB_TYPE.':host='.DB_HOST.';dbname='.DB_NAME, DB_USER, DB_PASS); } catch(PDOException $e) { throw new CoreException($e->getMessage()); } try { $this->language = new Language($lang); } catch(LangException $e) { throw new CoreException($e->getMessage()); } try { $this->theme = new Theme($theme); } catch(ThemeException $e) { throw new CoreException($e->getMessage()); } } return self::$instance; } public function getSite($what) { return $this->language->getLang(); } private function __clone() { } } Class managing themes class Theme { private $theme; public function __construct($name = 'default') { if(!is_dir("themes/$name")) { throw new ThemeException("Unable to load theme $name"); } else { $this->theme = $name; } } public function getTheme() { return $this->theme; } public function display($part) { if(!is_file("themes/$this->theme/$part.php")) { throw new ThemeException("Unable to load theme part: themes/$this->theme/$part.php"); } else { return 'So far so good'; } } } And usage: error_reporting(E_ALL); require_once('config.php'); require_once('functions.php'); try { $core = new Core(); } catch(CoreException $e) { echo 'Core Exception: '.$e->getMessage(); } echo $core->theme->getTheme(); echo "<br />"; echo $core->language->getLang(); try { $core->theme->display('footer'); } catch(ThemeException $e) { echo $e->getMessage(); } I don't like those exception handlers - i don't want to catch them like some pokemons... I want to use things simple: $core-theme-display('footer'); And if something is wrong, and debug mode is enabled, then aplication show error. What should i do?

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  • how to get the parent dir location using python..

    - by zjm1126
    this code is get the templates/blog1/page.html in b.py: path = os.path.join(os.path.dirname(__file__), os.path.join('templates', 'blog1/page.html')) but i want to get the parent dir location: a |---b.py |---templates |--------blog1 |-------page.html and how to get the a location thanks

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  • How do I set up my @product=Product.find(params[:id]) to have a product_url?

    - by montooner
    Trying to recreate { script/generate scaffold }, and I've gotten thru a number of Rails basics. I suspect that I need to configure default product url somewhere. But where do I do this? Setup: Have: def edit { @product=Product.find(params[:id]) } Have edit.html.erb, with an edit form posting to action = :create Have def create { ... }, with the code redirect_to(@product, ...) Getting error: undefined method `product_url' for #< ProductsController:0x56102b0 My def update: def update @product = Product.find(params[:id]) respond_to do |format| if @product.update_attributes(params[:product]) format.html { redirect_to(@product, :notice => 'Product was successfully updated.') } format.xml { head :ok } else format.html { render :action => "edit" } format.xml { render :xml => @product.errors, :status => :unprocessable_entity } end end end

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  • Use C function in C++ program; "multiply-defined" error

    - by eom
    I am trying to use this code for the Porter stemming algorithm in a C++ program I've already written. I followed the instructions near the end of the file for using the code as a separate module. I created a file, stem.c, that ends after the definition and has extern int stem(char * p, int i, int j) ... It worked fine in Xcode but it does not work for me on Unix with gcc 4.1.1--strange because usually I have no problem moving between the two. I get the error ld: fatal: symbol `stem(char*, int, int)' is multiply-defined: (file /var/tmp//ccrWWlnb.o type=FUNC; file /var/tmp//cc6rUXka.o type=FUNC); ld: fatal: File processing errors. No output written to cluster I've looked online and it seems like there are many things I could have wrong, but I'm not sure what combination of a header file, extern "C", etc. would work.

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