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  • array, I/O file and standard deviation (c++)

    - by JohnWong
    double s_deviation(double data[],int cnt, double mean) { int i; double sum= 0; double sdeviation; double x; //x = mean(billy,a_size); for(i=0; i<cnt; i++) { sum += ((data[i]) - (mean)); } sdeviation = sqrt(sum/((double)cnt)); return sdeviation; } When I cout the result from this function, it gave me NaN. I tested the value of (mean) and data[i] using return data[i] and return mean they are valid. when i replaced mean with an actual number, the operation returned a finite number. but with mean as a variable, it produced NaH. I can't see anything wrong with my code at the moment. Again, I am sure mean, data are getting the right number based on those tests. Thank you

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  • Why can't I access the instance.__class__ attribute in Python?

    - by froadie
    I'm new to Python, and I know I must be missing something pretty simple, but why doesn't this very, very simple code work? class myClass: pass testObject = myClass print testObject.__class__ I get the following error: AttributeError: class myClass has no attribute '__class__' Doesn't every object in Python have a __class__ attribute?

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  • Sort database entries via a dropdown list

    - by Lin
    Hello! I'm curious if anyone could possibly help me, because I can't find anything exactly related to it anywhere, and it's driving me nuts. I'd like to have a dropdown list on a page, that will give the visitor the option to sort all entries by year. I have entries from i.e. 2001, 2005, 2009, 2010. The years should be displayed in the dropdown, so the visitor can easily just select all entries dated 2001 if they want. The year for each entry is located in the one database table I have. In other words, I simply want a "sort by" dropdown that you can see on pretty much any shopping site nowadays. But with set years. Thanks in advance for any replies!

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  • mapping list of different types implementing same function?

    - by sisif
    I want to apply a function to every element in a list (map) but the elements may have different types but all implement the same function (here "putOut") like an interface. However I cannot create a list of this "interface" type (here "Outputable"). How do I map a list of different types implementing the same function? main :: IO () main = do map putOut lst putStrLn "end" where lst :: [Outputable] -- ERROR: Class "Outputable" used as a type lst = [(Out1 1),(Out2 1 2)] class Outputable a where putOut :: a -> IO () -- user defined: data Out1 = Out1 Int deriving (Show) data Out2 = Out2 Int deriving (Show) instance Outputable Out1 where putOut out1 = putStrLn $ show out1 instance Outputable Out2 where putOut out2 = putStrLn $ show out2 I cannot define it this way: data Out = Out1 Int | Out2 Int Int putOut Out1 = ... putOut Out2 = ... because this is a library and users should be able to extend Out with their own types

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  • C++ function-pointer and inheritance

    - by pingvinus
    In parent class I have function, that operates under an array of functions, declared in child-class, number of functions for every child-class may vary. But since every function uses some object-variables, I can't declare them as static. I've try to do something like this: class A { public: typedef int (A::*func)(); func * fs; void f() { /*call functions from this->fs*/ } }; class B : public A { public: int smth; B(int smth) { this->smth = smth; this->fs = new func[1]; fs[0] = &B::f; } int f() { return smth + 1; } }; But, obviously it doesn't work. Any suggestions?

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  • C++ Template problem adding two data types

    - by Sara
    I have a template class with an overloaded + operator. This is working fine when I am adding two ints or two doubles. How do I get it to add and int and a double and return the double? template <class T> class TemplateTest { private: T x; public: TemplateTest<T> operator+(const TemplateTest<T>& t1)const { return TemplateTest<T>(x + t1.x); } } in my main function i have void main() { TemplateTest intTt1 = TemplateTest<int>(2); TemplateTest intTt2 = TemplateTest<int>(4); TemplateTest doubleTt1 = TemplateTest<double>(2.1d); TemplateTest doubleTt2 = TemplateTest<double>(2.5d); std::cout << intTt1 + intTt2 << /n; std::cout << doubleTt1 + doubleTt2 << /n; } I want to be able to also do this std::cout << doubleTt1 + intTt2 << /n;

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  • 3D and AI basics. The foundation before the coding.

    - by Allan
    Hi, everyone. (If you have the time and patience:) I've recently made the decision to study programming seriously and I'm about to order TAOCP and Concrete Mathematics to begin my studies (please don't get caught up on this). I'm very much interested in learning and understanding how 3D works but I'm aware that if I plan to do it right there's still a long walk before I get to actually play with 3D coding. Now to the question.. (tl;dr) Excluding programming itself, what disciplines do I have to be familiar with to code 3D? What kinds of mathematics? Physics? What else? What books do you recommend on such subjects? Now read it all again but replacing "3D" with "AI". Please don't recommend computer-specific books. The question is about the foundation to be learned before using the machine. Also, if possible, please keep the list brief; I plan to order one book on each subject but no more than that for now. Excuse me for any English mistakes, it's not my first language. Thank you.

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  • for line in open(filename)

    - by foosion
    I frequently see python code similar to for line in open(filename): do_something(line) When does filename get closed with this code? Would it be better to write with open(filename) as f: for line in f.readlines(): do_something(line)

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  • Java NullPointerException. Why?

    - by user292844
    I am new to Java. I just read that class variables in Java have default value. I tried the following program. I was expecting to get the output as 0, which is the default value on an integer, but I get the NullPointerException. What am I missing? class Test{ static Integer iVar; public static void main(String...args) { System.out.println(iVar.intValue()); } }

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  • How to join list of strings?

    - by satsurae
    Hi all, This is probably seriously easy to solve for most of you but I cannot solve this simply putting str() around it can I? I would like to convert this list: ['A','B','C'] into 'A B C'. Thanks in advance!!

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  • howto Debugging on PHP

    - by justjoe
    how we do basic debugging in PHP ? Can anybody share true horror story on debugging PHP application (or (even better) on PHP framework such Codeigniter and Wordpress) ? i love to hear real experience in case i have to encounter similar situation on my journey to learn PHP.

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  • Get information about a function in python, looking at source code

    - by Werner
    Hi, the following code comes from the matplotlib gallery: #!/usr/bin/env python from pylab import * x = array([10, 8, 13, 9, 11, 14, 6, 4, 12, 7, 5]) y = array([8.04, 6.95, 7.58, 8.81, 8.33, 9.96, 7.24, 4.26, 10.84, 4.82, 5.68]) I am new to python, and would like to change the content of x and y from an input file. I have two short questions: I could guess what array means, but once I see it on the code, how can I know to which library it belongs and more information about it? Should I use some kind of python debug commands? How do I insert the content of my input file into x? Thanks

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  • How to append() an element and set its style with css() at the same time with jQuery

    - by Acorn
    I tried: $('#canvas').append('<div class="tile"></div>').css({left: leftPos, top: topPos});, but that sets the style of #canvas rather than the appended element. I then tried: $('#canvas').append(('<div class="tile"></div>').css({left: leftPos, top: topPos}));, but that gives the error "Object <div class="tile"></div> has no method 'css'". How can I add the element and set its style at the same time?

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  • extract variables from an expression using javascript regexp

    - by powerboy
    For example, here is a string representing an expression: var str = 'total = sum(price * qty) * 1.09875'; I want to extract variables (i.e., 'total', 'price' and 'qty' but not 'sum' since 'sum' is a function name) from this expression. What is the regexp pattern in javascript? Variable name consists of letters, digits, or the underscore, beginning with letters or the underscore.

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  • C++: Trouble with templates (C2064)

    - by Rosarch
    I'm having compiler errors, and I'm not sure why. What am I doing wrong here: Hangman.cpp: set<char> Hangman::incorrectGuesses() { // Hangman line 103 return Utils::findAll_if<char>(guesses.begin(), guesses.end(), &Hangman::isIncorrectGuess); } bool Hangman::isIncorrectGuess(char c) { return correctAnswer.find(c) == string::npos; } Utils.h: namespace Utils { void PrintLine(const string& line, int tabLevel = 0); string getTabs(int tabLevel); template<class result_t, class Predicate> std::set<result_t> findAll_if(typename std::set<result_t>::iterator begin, typename std::set<result_t>::iterator end, Predicate pred) { std::set<result_t> result; // utils line 16 return detail::findAll_if_rec<result_t>(begin, end, pred, result); } } namespace detail { template<class result_t, class Predicate> std::set<result_t> findAll_if_rec(typename std::set<result_t>::iterator begin, typename std::set<result_t>::iterator end, Predicate pred, std::set<result_t> result) { // utils line 25 typename std::set<result_t>::iterator nextResultElem = find_if(begin, end, pred); if (nextResultElem == end) { return result; } result.insert(*nextResultElem); return findAll_if_rec(++nextResultElem, end, pred, result); } } This produces the following compiler errors: algorithm(83): error C2064: term does not evaluate to a function taking 1 arguments algorithm(95) : see reference to function template instantiation '_InIt std::_Find_if<std::_Tree_unchecked_const_iterator<_Mytree>,_Pr>(_InIt,_InIt,_Pr)' being compiled 1> with 1> [ 1> _InIt=std::_Tree_unchecked_const_iterator<std::_Tree_val<std::_Tset_traits<char,std::less<char>,std::allocator<char>,false>>>, 1> _Mytree=std::_Tree_val<std::_Tset_traits<char,std::less<char>,std::allocator<char>,false>>, 1> _Pr=bool (__thiscall Hangman::* )(char) 1> ] utils.h(25) : see reference to function template instantiation '_InIt std::find_if<std::_Tree_const_iterator<_Mytree>,Predicate>(_InIt,_InIt,_Pr)' being compiled 1> with 1> [ 1> _InIt=std::_Tree_const_iterator<std::_Tree_val<std::_Tset_traits<char,std::less<char>,std::allocator<char>,false>>>, 1> _Mytree=std::_Tree_val<std::_Tset_traits<char,std::less<char>,std::allocator<char>,false>>, 1> Predicate=bool (__thiscall Hangman::* )(char), 1> _Pr=bool (__thiscall Hangman::* )(char) 1> ] utils.h(16) : see reference to function template instantiation 'std::set<_Kty> detail::findAll_if_rec<result_t,Predicate>(std::_Tree_const_iterator<_Mytree>,std::_Tree_const_iterator<_Mytree>,Predicate,std::set<_Kty>)' being compiled 1> with 1> [ 1> _Kty=char, 1> result_t=char, 1> Predicate=bool (__thiscall Hangman::* )(char), 1> _Mytree=std::_Tree_val<std::_Tset_traits<char,std::less<char>,std::allocator<char>,false>> 1> ] hangman.cpp(103) : see reference to function template instantiation 'std::set<_Kty> Utils::findAll_if<char,bool(__thiscall Hangman::* )(char)>(std::_Tree_const_iterator<_Mytree>,std::_Tree_const_iterator<_Mytree>,Predicate)' being compiled 1> with 1> [ 1> _Kty=char, 1> _Mytree=std::_Tree_val<std::_Tset_traits<char,std::less<char>,std::allocator<char>,false>>, 1> Predicate=bool (__thiscall Hangman::* )(char) 1> ]

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  • utf8 format in xml

    - by hussain
    i want to know how to store this è (this type of symbols) in xml file if i store this symbol in xml file.. the file shows this symbol like ? i was inserted in front of xml file is <?xml version="1.0" encoding="UTF-8"?> but that doest not shows correct thanks and advance

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  • I know the big picture but can't put it in place

    - by Simbilim
    Hi, I'm interested in web development and by that I mean the bigger projects like facebook or twitter. I know the basics of java, css, php and mysql. I know there is a lot more out there. I read about it. But I don't know what the purpose is and how to put in place. Things like: Scribe, thrift, casandra, Unix/Linux, shell/perl/python scripting, PostgreSQL, MongoDB, non-relational NoSQL datastores, JVM, nginx I want to know why they need it, how they use it and what te purpose is. What I need is a book like technical background of facebook for dummies or so. Are there any books or websites that explain this from scratch? Thank you!

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  • how to determine count of tag

    - by peter
    I have a bit of xml file named Sample.xml which is shown below <?xml version="1.0" encoding="ISO-8859-1"?> <countries> <country> <text>Norway</text> <value>N</value> </country> <country> <text>Sweden</text> <value>S</value> </country> <country> <text>France</text> <value>F</value> </country> <country> <text>Italy</text> <value>I</value> </country> </countries> i have button named submit(button1).If i click that button i need to display the count(PartitionName="AIX") in a text box named textBox1, means How many PartitionName="AIX" is belonging to Type="NIC" Can any one give me the c# code I did like this,,but not able to get the answaer private void button1_Click(object sender, EventArgs e) { XmlDocument doc1 = new XmlDocument(); doc1.Load(@"D:\New Folder\WindowsFormsApplication3\WindowsFormsApplication3\Sample.xml"); XmlNodeList a = doc1.GetElementsByTagName("AIX"); textBox1.Text = a.Count.ToString(); }

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  • Creating a Modeless Dialog

    - by Tom
    I'm trying to create a child modeless dialog of a dialog and currently I'm using these style parameters: STYLE DS_SETFONT | DS_MODALFRAME | DS_FIXEDSYS | WS_POPUP | WS_CAPTION | WS_SYSMENU EXSTYLE WS_EX_TOOLWINDOW I'm not being able to transfer the control its parent dialog once i try to create its child dialog. is there anything else I'm missing in the process to make the dialog modeless?

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  • Importing data from file to array

    - by stamp
    I have 2 dimensional table in file, which look like this: 11, 12, 13, 14, 15 21, 22, 23, 24, 25 I want it to be imported in 2 dimensional array. I wrote this code: INTEGER :: SMALL(10) DO I = 1, 3 READ(UNIT=10, FMT='(5I4)') SMALL WRITE(UNIT=*, FMT='(6X,5I4)') SMALL ENDDO But it imports everything in one dimensional array.

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