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  • Ruby on Rails : How can i display data for the current view from a different table

    - by krishkule
    This might be a easy-to-answer question, but its a pain in the bum for me.... So... I have two tables - Chords - |id|chord|name|rating|artist_id| Artists - |id|artist| (the relations : chords : belongs_to :artist artists : has_many :chords ) And in the index page for "chords" i want to display chord,name,rating from Chords table AND artist from the Artists table this is the code for the chrod's index.html.erb : <table border="1"> <%@chords.each do |chord|%> <tr> <td><%=chord.artist.artist%></td> <td><%= link_to chord.name, chord %></td> <td><%=chord.rating%></td> <td><%= chord.created_at %></td> </tr> <%end%> </table> The error message is : undefined method `artist' for nil:NilClass Actually, at first it worked, but when i started to create the "new.html.erb" page and the create,new controllers, it stopped working - thats why this is so confusing for me! I will be glad to hear any critique and suggestions! Thank you

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  • passing self data into a recursive function

    - by user272689
    I'm trying to set a function to do something like this def __binaryTreeInsert(self, toInsert, currentNode=getRoot(), parentNode=None): where current node starts as root, and then we change it to a different node in the method and recursivly call it again. However, i cannot get the 'currentNode=getRoot()' to work. If i try calling the funcion getRoot() (as above) it says im not giving it all the required variables, but if i try to call self.getRoot() it complains that self is an undefined variable. Is there a way i can do this without having to specify the root while calling this method?

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  • Weird IF THAN not working with Requested data from URL text problem

    - by StealthRT
    Hey all, i am checking for an internet connection by checking for a file on my server. The file only has the word LIVE displayed on the page. No HTML or anything else is there, just the word LIVE. When i run this code, i do get the NSLog as saying "LIVE" but once i go to check it with the IF statement, it fails and i just do not know why??? NSString* myFile = [NSString stringWithFormat:@"http://www.xxx.com/iPodTouchPing.html"]; NSString* myFileURLString = [myFile stringByReplacingPercentEscapesUsingEncoding:NSASCIIStringEncoding]; NSData *myFileData = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:myFileURLString]]; NSString *returnedMyFileContents=[[[NSString alloc] initWithData:myFileData encoding:NSASCIIStringEncoding] autorelease]; NSLog(@"%@", connected); if (connected == @"LIVE") { ... What am i doing wrong? I can not seem to find the reason?? David

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  • Binary search in rotated sorted list

    - by Algorist
    I am having a sorted list which is rotated and I would like to do a binary search on that list to find the minimum element. Lets suppose initial list is {1,2,3,4,5,6,7,8} rotated list can be like {5,6,7,8,1,2,3,4} Normal binary search doesn't work in this case. Any idea how to do this.

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  • java: copy-on-write data structure?

    - by Jason S
    Is there anything in Java that implements something like the following interface MSet<T> extends Iterable<T> { /** * return a new set which consists of this set plus a new element. * This set is not changed. */ MSet<T> add(T t); /** * return a new set which consists of this set minus a designated element. * This set is not changed. */ MSet<T> remove(T t); }

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  • Cannot access data in a xml string

    - by Jess McKenzie
    I am trying to create an array that I can include the perent category Name and the child category Name. I can so far access the below object fine using $xml->Subcategories; but if I try my code below I get an empty array why? PHP: foreach ($catDetailsXml->Category as $value) { $categoryDetails[] = array('CategoryNumber' => $value->Number); } Structure: object(SimpleXMLElement)#13 (1) { ["Category"]=> array(5) { [0]=> object(SimpleXMLElement)#14 (4) { ["Name"]=> string(19) "Commercial Property" ["Number"]=> string(10) "0350-0100-" ["Subcategories"]=> object(SimpleXMLElement)#35 (1) { ["Category"]=> array(3) { [0]=> object(SimpleXMLElement)#36 (4) { ["Name"]=> string(9) "Car parks" ["Number"]=> string(15) "0350-0100-8946-" ["Subcategories"]=> object(SimpleXMLElement)#39 (0) { } }

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  • Determine stale data

    - by Andrei
    Say I have a file of this format 12:04:21 .3 12:10:21 1.3 12:13:21 1.4 12:14:21 1.3 ..and so on I want to find repeated numbers in the second column for, say, 10 consequent timestamps, thereby finding staleness. and I want to output the beginning and and end of the stale timestamp range Can someone help me come up with it? You can use awk, bash Thanks

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  • Checking status after wait()

    - by Helper Method
    After creating a child process and exiting it immediately (_exit()), I want to perform a wait and check the status. Now I wonder if in the 'else' branch of the if/else construct I also need to check for WIFSIGNALED. As far as I understand, if I perform a wait, a) an error could have occured (-1), the child could have terminated normally by an (exit() or _exit()), or it could have been terminated by a signal, so the check could be omitted, right? //remainder omitted int status; pid_t t_pid = wait(&status); if (t_pid == -1) { perror("wait"); exit(EXIT_FAILURE); } if (WIFEXITED(status)) { printf("child terminated normally, status = %d\n", WEXITSTATUS(status) ); } else { // <-- do it have to check for WIFSIGNALED() here? printf("child was terminated by a signal, signum = %d\n", WTERMSIG(status) ); }

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  • Scraping data from Flash (Games)

    - by awegawef
    I saw this video, and I am really curious how it was performed. Does anyone have any ideas? My intuition is that he scraped pixels from the screen (one per 'box'), and then fed that into some program to determine the next move. Is scraping pixel-by-pixel the way to do this, or is there a better way? I am looking to do something similar with either Java or Python. Thanks

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  • choose the best class if 2 class have same P (c|d), naive bayes

    - by ryandi
    Hello I have some question about naive bayes classifier . In my project I have to classify a text into a class from 4 available class. In naive bayes we have formula like cmap=argmax.P(d|c).P(c) I have standarize the amount of training document of each class, so I got a same P(c) value for each class (0.25). Here's my question: What if a testing document token doesn't have any token which belong to any of those 4 class(in document training)? Resulted to all of the class have same value of P(d|c).P(c). Which class should i pick? What if the token exist, and 2 class or more have same value of P(d|c).P(c) what should I do? Thank you..

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  • Big-O for calculating all routes from GPS data

    - by HH
    A non-critical GPS module use lists because it needs to be modifiable, new routes added, new distances calculated, continuos comparisons. Well so I thought but my team member wrote something I am very hard to get into. His pseudo code int k =0; a[][] <- create mapModuleNearbyDotList -array //CPU O(n) for(j = 1 to n) // O(nlog(m)) for(i =1 to n) for(k = 1 to n) if(dot is nearby) adj[i][j]=min(adj[i][j], adj[i][k] + adj[k][j]); His ideas transformations of lists to tables His worst case time complexity is O(n^3), where n is number of elements in his so-called table. Exception to the last point with Finite structure: O(mlog(n)) where n is number of vertices and m is the amount of neighbour vertices. Questions about his ideas why to waste resources to transform constantly-modified lists to table? Fast? only point where I to some extent agree but cannot understand the same upper limits n for each for-loops -- perhaps he supposed it circular why does the code take O(mlog(n)) to proceed in time as finite structure? The term finite may be wrong, explicit?

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  • How do I remove the leaves of a binary tree?

    - by flopex
    I'm trying to remove all of the leaves. I know that leaves have no children, this is what I have so far. public void removeLeaves(BinaryTree n){ if (n.left == null && n.right == null){ n = null; } if (n.left != null) removeLeaves(n.left); if (n.right != null) removeLeaves(n.right); }

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  • Imputing missing data in aligned sequences

    - by Kwame Oduro
    I want a simple perl script that can help me impute missing nucleotides in aligned sequences: As an example, my old_file contains the following aligned sequences: seq1 ATGTC seq2 ATGTC seq3 ATNNC seq4 NNGTN seq5 CTCTN So I now want to infer all Ns in the file and get a new file with all the Ns inferred based on the majority nucleotide at a particular position. My new_file should look like this: seq1 ATGTC seq2 ATGTC seq3 ATGTC seq4 ATGTC seq5 CTCTC A script with usage: "impute_missing_data.pl old_file new_file" or any other approach will be helpful to me. Thank you.

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  • Merge two lists of objects which hold different data

    - by C.McAtackney
    I have an object "Project" which has a number of fields, one of which is "Name". I have one spreadsheet of projects which contains some of these fields, and another which contains the rest. However, Both spreadsheets have the "Name" field. I've read them in and populated two List, only populating the available fields from that particular source. E.g. a Project from List 1 looks like; {Name="MyProj", Type="Form", Priority=NULL}, whereas a Project from List 2 {Name="MyProj", Type=NULL, Priority="High"}. Now, I want to merge these two lists into one in which each Project object has all of its fields populated, with the Name field being used to match the elements. How can I achieve this? Are there any nice ways of doing this concisely? Thanks

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  • Python - from file to data structure?

    - by Seafoid
    Hi, I have large file comprising ~100,000 lines. Each line corresponds to a cluster and each entry within each line is a reference i.d. for another file (protein structure in this case), e.g. 1hgn 1dju 3nmj 8kfn 9opu 7gfb 4bui I need to read in the file as a list of lists where each line is a sublist, thus preserving the integrity of the cluster, e.g. nested_list = [['1hgn', '1dju', '3nmj', '8kfn'], ['9opu', '7gfb'], ['4bui']] My current code creates a nested list but the entries within each list are a single string and not comma separated. Therefore, I cannot splice the list with indices so easily. Any help greatly appreciated. Thanks, S :-)

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  • sending data packet just before closing socket

    - by xopht
    Before disconnect the client, the server wants to send some info to the client - why do I(server) disconnect you(client). If I send packet to the info and close the client socket immediately, closesocket() returns -1 and if I use linger option to work closesocket() successfully, the info cannot be sent completely. How can I complete this and is it possible to know socket buffer is empty(means my packet sent all)? thx.

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  • Error inserting data in binary tree

    - by chepe263
    I copied this code (in spanish) http://www.elrincondelc.com/nuevorincon/index.php?pag=codigos&id=4 and wrote a new one. This is my code: #include <cstdlib> #include <conio.h> #include <iostream> using namespace std; struct nodoarbol { int dato; struct nodoarbol *izq; struct nodoarbol *der; }; typedef nodoarbol Nodo; typedef Nodo *Arbol; void insertar(Arbol *, int); void inorden(Arbol); void postorden(Arbol); void preorden(Arbol); void insertar(Arbol *raiz, int nuevo){ if (*raiz==NULL){ *raiz = (Nodo *)malloc(sizeof(Nodo)); if (*raiz != NULL){ (*raiz)->dato=nuevo; (*raiz)->der=NULL; (*raiz)->izq=NULL; } else{ cout<<"No hay memoria suficiente u ocurrio un error"; } } else{ if (nuevo < (*raiz)->dato) insertar( &((*raiz)->izq), nuevo ); else if (nuevo > (*raiz)->dato) insertar(&((*raiz)->der), nuevo); } }//inseertar void inorden(Arbol raiz){ if (raiz != NULL){ inorden(raiz->izq); cout << raiz->dato << " "; inorden(raiz->der); } } void preorden(Arbol raiz){ if (raiz != NULL){ cout<< raiz->dato << " "; preorden(raiz->izq); preorden(raiz->der); } } void postorden(Arbol raiz){ if (raiz!=NULL){ postorden(raiz->izq); postorden(raiz->der); cout<<raiz->dato<<" "; } } int main() { int i; i=0; int val; Arbol raiz = NULL; for (i=0; i<10; i++){ cout<<"Inserte un numero"; cin>>val; insertar( (raiz), val); } cout<<"\nPreorden\n"; preorden(raiz); cout<<"\nIneorden\n"; inorden(raiz); cout<<"\nPostorden\n"; postorden(raiz); return 0; } I'm using netbeans 7.1.1, mingw32 compiler This is the output: make[2]: Leaving directory `/q/netbeans c++/NetBeansProjects/treek' make[1]: Leaving directory `/q/netbeans c++/NetBeansProjects/treek' main.cpp: In function 'int main()': main.cpp:110:30: error: cannot convert 'Arbol {aka nodoarbol*}' to 'Nodo** {aka nodoarbol**}' for argument '1' to 'void insertar(Nodo**, int)' make[2]: *** [build/Release/MinGW-Windows/main.o] Error 1 make[1]: *** [.build-conf] Error 2 make: *** [.build-impl] Error 2 BUILD FAILED (exit value 2, total time: 11s) I don't understand what's wrong since i just copied the code (and rewrite it to my own code). I'm really good in php, asp.net (vb) and other languages but c is a headche for me. I've been struggling with this problem for about an hour. Could somebody tell me what could it be?

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  • drag-drop and data binding in MVVM

    - by Benny
    My ViewModel: class ViewModel { public string FileName {get;set;} } and in my View I bind a label's content to ViewModel's FileName. now When I do drag-drop a file to my View, How can I update the label's Content property, so that the ViewMode's FileName also get updated via binding? Directly set the label's Content property won't work, it just simply clear the binding.

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  • NSFetchedResultsController deallocated instance

    - by Jesse Armand
    Anyone ever encountered this ? -[NSFetchedResultsController _restoreCachedSectionInfo]: message sent to deallocated instance While performing fetch with performFetch: using NSFetchedResultsController instance. I'm sure the NSFetchedResultsController is retained before performing the fetch.

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  • Strange behavior: save video recorded within app?

    - by Josue Espinosa
    I allow the user to record a video within my app, then later play it again. When a user records a video, I save the URL of the video, then play the video later from the saved URL. I save the video both in the Photos app and in my app. If I delete the video within the photos app, it still plays. After about 7 days, the video gets deleted. I think I am saving in my tmp directory, but i'm not sure. Here is what I am doing: -(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info { NSString *mediaType = [info objectForKey: UIImagePickerControllerMediaType]; [self dismissViewControllerAnimated:YES completion:nil]; // Handle a movie capture if (CFStringCompare ((__bridge_retained CFStringRef) mediaType, kUTTypeMovie, 0) == kCFCompareEqualTo) { NSString *moviePath = [NSString stringWithFormat:@"%@",[[info objectForKey:UIImagePickerControllerMediaURL] path]]; NSURL *videoURL = [info objectForKey:UIImagePickerControllerMediaURL]; NSData *videoData = [NSData dataWithContentsOfURL:videoURL]; _justRecordedVideoURL = [NSString stringWithFormat:@"%@",videoURL]; AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate]; _managedObjectContext = [appDelegate managedObjectContext]; Video *video = [NSEntityDescription insertNewObjectForEntityForName:@"Video" inManagedObjectContext:_managedObjectContext]; [video setVideoData:videoData]; [video setVideoURL:[NSString stringWithFormat:@"%@",videoURL]]; NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init]; dateFormatter.dateStyle = NSDateFormatterLongStyle; [dateFormatter setDateStyle:NSDateFormatterLongStyle]; NSDate *date = [dateFormatter dateFromString:[dateFormatter stringFromDate:[NSDate date]]]; NSString *dateAdded = [dateFormatter stringFromDate:date]; [video setDate_recorded:dateAdded]; if(_currentAthlete != nil){ [video setWhosVideo:_currentAthlete]; } NSError *error = nil; if(![_managedObjectContext save:&error]){ //handle dat error } NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths objectAtIndex:0]; NSString *tempPath = [documentsDirectory stringByAppendingFormat:@"/vid1.mp4"]; BOOL success = [videoData writeToFile:tempPath atomically:NO]; if(success == FALSE){ NSLog(@"Video was not successfully saved."); } if (UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(moviePath)) { UISaveVideoAtPathToSavedPhotosAlbum(moviePath, self, @selector(video:didFinishSavingWithError:contextInfo:), nil); } } } Am I saving it incorrectly? When I go to play the video, it works fine, after a couple days the video will play without audio, then eventually it will be gone. Any ideas why?

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  • Huge Graph Structure

    - by Harph
    I'm developing an application in which I need a structure for represent a huge graph (between 1000000 and 6000000 nodes and 100 or 600 edges) in memory. The edges representation will contain some attribute of the relation. I have tried a memory map representation, arrays, dictionaries and string for represent that structure in memory, but this always crash because the memory limit. I would to get an advice of how can I represent this, or something similar. By the way, I'm using python.

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  • Django query filter a set of data

    - by dana
    if a have a query like following = Relations.objects.filter(initiated_by = request.user) in which i'm having all the users followed by the currently logged in user, and i want to display those user's blog posts. Using a query like: blog = New.objects.filter(created_by = following) it only shows me the blog posts of the user with the id = 1 (though the currently logged in user doesn't actually follow him) in template i have : {% for object in blog %} <a href='/accounts/profile_view/{{object.created_by}}/'> {{object.created_by}}</a> <br /> {{object.post}}<br /> {% endfor %} Where am i wrong?

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  • algorithm - How to sort a 0/1 array with 2n/3 comparisons?

    - by Jackson Tale
    In Algorithm Design Manual, there is such an excise 4-26 Consider the problem of sorting a sequence of n 0’s and 1’s using comparisons. For each comparison of two values x and y, the algorithm learns which of x < y, x = y, or x y holds. (a) Give an algorithm to sort in n - 1 comparisons in the worst case. Show that your algorithm is optimal. (b) Give an algorithm to sort in 2n/3 comparisons in the average case (assuming each of the n inputs is 0 or 1 with equal probability). Show that your algorithm is optimal. For (a), I think it is fairly easy. I can choose a[n-1] as pivot, then do something like in quicksort partition, scan 0 to n - 2, find the middle point where left side is all 0 and right side is all 1, this take n - 1 comparisons. But for (b), I can't get a clue. It says "each of the n inputs is 0 or 1 with equal probability", so I guess I can assume the numbers of 0 and 1 equal? But how can I get a result which is related to 1/3? divide the whole array into 3 groups? Thanks

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  • about Sorting Algorithms

    - by matin1234
    Hi I want to know that we always use Sorting algorithm like (Insertion Sort or Merge Sort,...) just for lists and arrays?? and we do not use these algorithms for stack or queue ??? thanks

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