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  • Is the FoldLeft function available in R?

    - by JSmaga
    Hi, I would like to know if there is an implementation of the foldLeft function (and foldRight?) in R. The language is supposed to be "rather" functional oriented and hence I think there should be something like this, but I could not find it in the documentation. To me, foldLeft function applies on a list and has the following signature: foldLeft[B](z : B)(f : (B, A) => B) : B It is supposed to return the following result: f(... (f(f(z, a0), a1) ...), an) if the list is [a0, a1, ..., an]. (I use the definition of the Scala List API) Does anybody know if such a function exists in R?

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  • How to delete Drawn Line in java?

    - by Jeyjey
    Hello Folks, well this is my code: import javax.swing.; import javax.; import java.awt.; import java.awt.Color; import java.awt.Graphics.; import java.awt.event.*; import javax.swing.UIManager; public class SimpleGUI extends JFrame{ public SimpleGUI(){ this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE) ; } public void go(){ Drawpanel = new Mypanel(); JFrame frame = new JFrame("Chasing Line"); frame.getContentPane().add(BorderLayout.CENTER, Drawpanel); frame.setSize(300,300); frame.setVisible(true); Drawpanel.addMouseMotionListener(new java.awt.event.MouseMotionAdapter() { public void mouseMoved(java.awt.event.MouseEvent evt) { DrawpanelMouseMoved(evt); } }); } public void DrawpanelMouseMoved(java.awt.event.MouseEvent evt) { xpos=evt.getX(); ypos=evt.getY(); System.out.println("Coordinates : X :"+ xpos+"Y: "+ypos); Drawpanel.paintImage(xpos,ypos); } class Mypanel extends JPanel{ public void paintImage(int xpost,int ypost){ Graphics d = getGraphics(); d.setColor(Color.black); d.drawLine(xpost, 0, xpost, this.getHeight()); d.setColor(Color.red); d.drawLine(0, ypost, this.getWidth(),ypost); this.validate(); } } // end the inner class public static void main(String[] args){ try { UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel"); } catch(Exception e) { System.err.println("Look and feel not set"); } SimpleGUI win = new SimpleGUI(); win.go(); } Mypanel Drawpanel; private int xpos=0; private int ypos=0; } // close SimpleGUI class The problem is how can i delete the old lines?, i mea,make only the current x and y lines appear on the screen, make the intersection between both lines "follow" the mouse pointer. thanks for any reply.

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  • How to implemenet Password Resets

    - by Sanju
    Hi, I have an existing application that i want to implement password resets after 30 days. But i dont want the user to use the same password as the last 5 times. How do i go about doing this or is there any links i can follow. Please help Thanks,

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  • error : [0.8879153] kernel panic -not syncing VFS unable to mount fs unknow block (8.3)

    - by Fiasco
    hello i installed ubuntu using wubit inside the windows and started working on it then i got this error afer updating [0.8879153] kernel panic -not syncing VFS unable to mount fs unknow block (8.3) and i can't user rescue mode and it's give me another error no filesystem could mount root ..... i looked at grub folder and didn' find any file on disks/boot/grub/ so i tryed to user super grub to fix it but it didn' work and it keep giving me. any idea plz .

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  • errors on shell

    - by lego69
    somebody knows what does this error mean? Usage: tcsh [ -bcdefilmnqstvVxX ] [ argument ... ]. I receive this error after I enter in my script this row #! /bin/tcsh -f

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  • What 20 Lines (or less) of code did you find really useful?

    - by Ygam
    You can share your code or other's code. Here's a snippet from an array function in Kohana: public static function rotate($source_array, $keep_keys = TRUE) { $new_array = array(); foreach ($source_array as $key => $value) { $value = ($keep_keys === TRUE) ? $value : array_values($value); foreach ($value as $k => $v) { $new_array[$k][$key] = $v; } } return $new_array; } It was helpful when I was uploading multiple images using multiple file upload forms. It turned this array array('images' => array( 'name' => array( 0 => 'img1', 1 => 'img0', 2 =>'img2' ), 'error' => array( 0 => '', 1 => '', 2 => '' into : array('images' => array( 0 => array( 'name' => 'img1' 'error' => '' ),//rest goes here How about you? What 20 or less lines of code did you find useful?

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  • What are the best websites/web applications for specific languages?

    - by JM4
    Browsing around Stackoverflow, I get overwhelmed with the number of "Why should I learn Python/Ruby/PHP/.Net/jQuery..." and the list goes on. Most answers, although good, are usually battles from language A programmer to language B programmer detailing why one piece sucks more than another. People can discuss the theoretical benefits of one over another but in the end, money/glitz talks and the rest walks. I am more interested in the potential opportunity that can come from one language or another over others. A little background, I am a project manager turned novice 'programmer' out of corporate necessity within the small company I currently work with so I have both relatively no set preference or experience, more out of curiosity. While I realize all are not created equal and for similar things, I think it would be interesting to start a list of the best websites / web applications built on specific languages/frameworks just to highlight the possibilities with each and give somebody like me motivation to say "How the heck was that done? Time to buy a book/take a class and learn." Tell me and I will forget, Show me and I will learn, Involve me and I will understand - Teton Lakota

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  • Abort early in a fold

    - by Heptic
    What's the best way to terminate a fold early? As a simplified example, imagine I want to sum up the numbers in an Iterable, but if I encounter something I'm not expecting (say an odd number) I might want to terminate. This is a first approximation def sumEvenNumbers(nums: Iterable[Int]): Option[Int] = { nums.foldLeft (Some(0): Option[Int]) { case (None, _) => None case (Some(s), n) if n % 2 == 0 => Some(s + n) case (Some(_), _) => None } } However, this solution is pretty ugly (as in, if I did a .foreach and a return -- it'd be much cleaner and clearer) and worst of all, it traverses the entire iterable even if it encounters a non-even number. So what would be the best way to write a fold like this, that terminates early? Should I just go and write this recursively, or is there a more accepted way?

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  • Multiplying numbers on horizontal, vertial, and diagonal lines

    - by untwisted
    I'm currently working on a project Euler problem (www.projecteuler.net) for fun but have hit a stumbling block. One of the problem provides a 20x20 grid of numbers and asks for the greatest product of 4 numbers on a straight line. This line can be either horizontal, vertical, or diagonal. Using a procedural language I'd have no problem solving this, but part of my motivation for doing these problems in the first place is to gain more experience and learn more Haskell. As of right now I'm reading in the grid and converting it to a list of list of ints, eg -- [[Int]]. This makes the horizontal multiplication trivial, and by transposing this grid the vertical also becomes trivial. The diagonal is what is giving me trouble. I've thought of a few ways where I could use explicit array slicing or indexing, to get a solution, but it seems overly complicated and hackey. I believe there is probably an elegant, functional solution here, and I'd love to hear what others can come up with.

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  • Efficiently get the size of a parameter pack up to a certain index

    - by NmdMystery
    I want to be able to determine the number of bytes that are in a subset of a parameter pack from 0 to a given index. Right now I'm using a non-constexpr way of doing this. Below is my code: template <size_t index, typename... args> struct pack_size_index; template <size_t index, typename type_t, typename... args> struct pack_size_index <index, type_t, args...> { static const size_t index_v = index; static const size_t value(void) { if (index_v > 0) { return sizeof(type_t) + pack_size_index<index - 1, args...>::value(); } return 0; } }; template <size_t index> struct pack_size_index <index> { static const size_t index_v = index; static const size_t value(void) { return 0; } }; Usage: //output: 5 (equal to 1 + 4) std::cout << pack_size_index<2, bool, float, int, double>::value() << std::endl; //output: 20 (equal to 8 + 8 + 4) std::cout << pack_size_index<3, double, double, float, int>::value() << std::endl; This gets the job done, but this uses runtime comparison and the resulting executable increases in size rapidly whenever this is used. What's a less expensive way of doing this?

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  • What type of programs are C/C++ used for now?

    - by Ryan Detzel
    I started off with C in school, went to Java and now I primarily use the P's(Php, Perl, Python) so my exposure to the lower level languages have all but disappeared. I would like to get back into it but I can never justify using C over Perl or Python. What real-world apps are being built with these languages? Any suggestions if I want to dive back in, what can I do with C/C++ that I can't easily do with Perl/Python?

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  • possible implementations of casting in c++

    - by lego69
    I have this snippet of the code in my header: class A { private: int player; public: A(int initPlayer = 0); A(const A&); A& operator=(const A&); ~A(); void foo() const; friend int operator==(const A& i, const A& member) const; }; implementation of the operator== int operator==(const A& i, const A& member) const{ if(i.player == member.player){ return 1; } return 0; } and I need casting for this part of my code: A *pa1 = new A(a2); assert(i == *pa1); i - is some int, which my function receives I receive an error non-member function, How can I fix it? thanks in advance

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  • how to detect datacard connect and disconnect event on win32

    - by Vinayaka Karjigi
    Hi All, I have a data card, as soon as i insert the data card, i am getting the events by using wm_device_change event. But I also want to get event, when my data connect actually connects to out side world. I mean to say, as soon as we click on connect/disconnect button of data card,i want to get the event. exactly speaking wanted to know, when connection is established and disconnected. data card is vodaphone data card and i am trying to browse using that data card. what ever is the SDK, somewhere the OS should get the event of connection and disconnection to network is there any way to access that event which OS is getting. as i can see in notificaiton the changes of vodaphone connection and LAN connection data card is a USB device having SIM within it, and can be used to access internet through GPRS. can i know how to do this in win32 c/c++ programe. with regards Vinayaka Karjigi

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  • what is the accepted naming convention for int, string, array, list, object, etc...

    - by RJ
    The company I work for now uses a set naming convention for their C# variables such as iSomeName for int, sSomeName for string, aSomeName for arrays, bSomeName for boolean, dSomeName for datetime and so on. My previous employer did not use the i, s, a, b and d prefixes and just named the variables a good understandable name. My impression is that these prefixes lost favor a while ago and from what I read it is not the current trend. It seems fine to me either way as long as the variable is descriptive enough to understand what it is doing but I was wondering what the now-a-day accepted practice is for naming variables?

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  • Do we really need high level languages? [closed]

    - by i_love_c
    Seeing the amount of softwares developed (and still being developed) in C and considering the fact that C currently tops the TIOBE chart, I have this one question for you all: Do we really need high level languages like C# or F# or Ruby? Don't you think these so-called high level languages are actually spoiling programmers and resulting in suboptimal and non-efficient softwares?

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