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  • How do I implement graphs and graph algorithms in a functional programming language?

    - by brad
    Basically, I know how to create graph data structures and use Dijkstra's algorithm in programming languages where side effects are allowed. Typically, graph algorithms use a structure to mark certain nodes as 'visited', but this has side effects, which I'm trying to avoid. I can think of one way to implement this in a functional language, but it basically requires passing around large amounts of state to different functions, and I'm wondering if there is a more space-efficient solution.

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  • [Facebook Graph API - Android] I want to know the HTTPSConnection redirected to which URL?

    - by Mohammad Abdelaziz
    I am building an application that uses the Facebook Graph API. To get the access token I should send the following request https://graph.facebook.com/oauth/authorize? client_id=...& redirect_uri=http://www.example.com/callback It redirects to the redirect_uri with the code to be used as access token. How can I capture that the HttpsURLConnection is redirected and how to get the code? Is it possible or I need to have server that gets the access token?

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  • How can I store this kind of graph in neo4j for fast traversal?

    - by James
    This is a graph whose nodes exist in many connected components at once because a node's relationships are a collection of edge groups such that only one edge per edge group can be present at once. I need to be able to find all of the connected components that a node exists in. What would be the best way to store this graph in neo4j to quickly find all of the connected components that a node exists in? Is there a way to use the built in traversals to do this? Also: is there a name for this kind of graph? I'd appreciate any help/ideas. Update: Sorry for not being clear. All nodes are of the same type. Nodes have a variable number of edge groups. Exactly one edge from each edge group needs to be chosen for a particular connected component. I'm going to try to explain through example: Node x1 is related to: (x2 or x3 or x4) AND (x5 or x6) AND (x7) Node x2 is related to: (x8) AND (x9 or x10) So x1's first edge group is (x2, x3, x4), its second edge group is (x5, x6), and its third edge group is (x7). So here are a few connected components that x1 exists in: CC1: x1 is related to: x2, x5, x7 x2 is related to: x8 x9 CC2: x1 is related to: x2, x6, x7 x2 is related to: x8, x9 CC3: x1 is related to: x3, x5, x7 CC4: x1 is related to: x3, x6, x7 etc. I'm grateful for your help in this.

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  • How to return array of C++ objects from a PHP extension

    - by John Factorial
    I need to have my PHP extension return an array of objects, but I can't seem to figure out how to do this. I have a Graph object written in C++. Graph.getNodes() returns a std::map<int, Node*>. Here's the code I have currently: struct node_object { zend_object std; Node *node; }; zend_class_entry *node_ce; then PHP_METHOD(Graph, getNodes) { Graph *graph; GET_GRAPH(graph, obj) // a macro I wrote to populate graph node_object* n; zval* node_zval; if (obj == NULL) { RETURN_NULL(); } if (object_init_ex(node_zval, node_ce) != SUCCESS) { RETURN_NULL(); } std::map nodes = graph-getNodes(); array_init(return_value); for (std::map::iterator i = nodes.begin(); i != nodes.end(); ++i) { php_printf("X"); n = (node_object*) zend_object_store_get_object(node_zval TSRMLS_CC); n-node = i-second; add_index_zval(return_value, i-first, node_zval); } php_printf("]"); } When i run php -r '$g = new Graph(); $g->getNodes();' I get the output XX]Segmentation fault meaning the getNodes() function loops successfully through my 2-node list, returns, then segfaults. What am I doing wrong?

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  • Qt Graphics et performance - velours et QML Scene Graph, un article de Gunnar, traduit par Thibaut Cuvelier

    Le 11 décembre 2009, la documentation de QPainter subissait un énorme ajout concernant l'optimisation de son utilisation. En effet, le bon usage de cet outil n'était pas accessible à tous, il n'était pas présenté dans la documentation. Ceci ne fut qu'un prétexte à une série d'articles sur l'optimisation de QPainter et de Qt Graphics en général. Voici donc le premier article de cette série, les autres sont en préparation : Qt Graphics et performances : ce qui est critique et ce qui ne l'est pas Pensez-vous que cet ajout à la documentation de QPainter sera utile ? Trouvez-vous les performances de vos applications trop faibles ?...

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  • How to customize the renders in prefuse. Problem in customize images in prefuse layout

    - by user324926
    HI all, I have written a java application to show the images in different layouts. I am able to show it different layout correctly but some times the images are overlapped. Can you please help me, how to solve this problem. My code is given below `import javax.swing.JFrame; import java.awt.image.BufferedImage; import javax.imageio.ImageIO; import java.util.; import java.io.; import java.awt.Font; import prefuse.Constants; import prefuse.Display; import prefuse.Visualization; import prefuse.action.ActionList; import prefuse.action.RepaintAction; import prefuse.action.assignment.ColorAction; import prefuse.action.assignment.FontAction; import prefuse.action.assignment.DataColorAction; import prefuse.action.layout.graph.ForceDirectedLayout; import prefuse.action.layout.graph.; import prefuse.action.layout.; import prefuse.activity.Activity; import prefuse.controls.DragControl; import prefuse.controls.PanControl; import prefuse.controls.ZoomControl; import prefuse.data.Graph; import prefuse.data.io.DataIOException; import prefuse.data.io.GraphMLReader; import prefuse.render.DefaultRendererFactory; import prefuse.render.LabelRenderer; import prefuse.util.ColorLib; import prefuse.visual.VisualItem; import prefuse.visual.*; import prefuse.util.FontLib; import prefuse.action.assignment.DataSizeAction; import prefuse.data.*; import prefuse.render.ImageFactory; public class LayoutExample { public static void main(String[] argv) throws Exception { Graph graph = null; try { graph = new GraphMLReader().readGraph("/graphs.xml"); } catch ( DataIOException e ) { e.printStackTrace(); System.err.println("Error loading graph. Exiting..."); System.exit(1); } ImageFactory imageFactory = new ImageFactory(100,100); try { //load images and construct imageFactory. String images[] = new String[3]; images[0] = "data/images/switch.png"; images[1] = "data/images/ip_network.png"; images[2] = "data/images/router.png"; String[] names = new String[] {"Switch","Network","Router"}; BufferedImage img = null; for(int i=0; i < images.length ; i++) { try { img = ImageIO.read(new File(images[i])); imageFactory.addImage(names[i],img); } catch (IOException e){ } } } catch(Exception exp) { } Visualization vis = new Visualization(); vis.add("graph", graph); LabelRenderer nodeRenderer = new LabelRenderer("name", "type"); nodeRenderer.setVerticalAlignment(Constants.BOTTOM); nodeRenderer.setHorizontalPadding(0); nodeRenderer.setVerticalPadding(0); nodeRenderer.setImagePosition(Constants.TOP); nodeRenderer.setMaxImageDimensions(100,100); DefaultRendererFactory drf = new DefaultRendererFactory(); drf.setDefaultRenderer(nodeRenderer); vis.setRendererFactory(drf); ColorAction nText = new ColorAction("graph.nodes", VisualItem.TEXTCOLOR); nText.setDefaultColor(ColorLib.gray(100)); ColorAction nEdges = new ColorAction("graph.edges", VisualItem.STROKECOLOR); nEdges.setDefaultColor(ColorLib.gray(100)); // bundle the color actions ActionList draw = new ActionList(); //MAD - changing the size of the nodes dependent on the weight of the people final DataSizeAction dsa = new DataSizeAction("graph.nodes","size"); draw.add(dsa); draw.add(nText); draw.add(new FontAction("graph.nodes", FontLib.getFont("Tahoma",Font.BOLD, 12))); draw.add(nEdges); vis.putAction("draw", draw); ActionList layout = new ActionList(Activity.DEFAULT_STEP_TIME); BalloonTreeLayout balloonlayout = new BalloonTreeLayout("graph",50); layout.add(balloonlayout); Display d = new Display(vis); vis.putAction("layout", layout); // start up the animated layout vis.run("draw"); vis.run("layout"); d.addControlListener(new DragControl()); // pan with left-click drag on background d.addControlListener(new PanControl()); // zoom with right-click drag d.addControlListener(new ZoomControl()); // -- 6. launch the visualization ------------------------------------- // create a new window to hold the visualization JFrame frame = new JFrame("prefuse example"); // ensure application exits when window is closed frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.add(d); frame.pack(); // layout components in window frame.setVisible(true); // show the window } } ` Can anyone please let me know how to customize the image sizes / renders insuch way that images won't overlapped. Thanks R.Ravikumar

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  • Rails - how can I capture the URL that directed to the current action in my app?

    - by sa125
    Hi - I need to see what page a request came from in my controller so I could be able to redirect back to it. For example, if I'm on a page showing a specific product (say /products/1) and it has a link to its vendor (/vendors/12), I want to be able to detect inside the vendors_controller that I came to that page from /products/1. Is there a simple way in Rails to achieve this, so that I could access it via params or session? thanks.

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  • graphviz segmentation fault

    - by LucaB
    Hi I'm building a graph with many nodes, around 3000. I wrote a simple python program to do the trick with graphviz, but it gives me segmentation fault and I don't know why, if the graph is too big or if i'm missing something. The code is: #!/usr/bin/env python # Import graphviz import sys sys.path.append('..') sys.path.append('/usr/lib/graphviz') import gv # Import pygraph from pygraph.classes.graph import graph from pygraph.classes.digraph import digraph from pygraph.algorithms.searching import breadth_first_search from pygraph.readwrite.dot import write # Graph creation gr = graph() file = open('nodes.dat', 'r') line = file.readline() while line: gr.add_nodes([line[0:-1]]) line = file.readline() file.close() print 'nodes finished, beginning edges' edges = open('edges_ok.dat', 'r') edge = edges.readline() while edge: gr.add_edge((edge.split()[0], edge.split()[1])) edge = edges.readline() edges.close() print 'edges finished' print 'Drawing' # Draw as PNG dot = write(gr) gvv = gv.readstring(dot) gv.layout(gvv,'dot') gv.render(gvv,'svg','graph.svg') and it crashes at the gv.layout() call. The files are somthing like: nodes: node1 node2 node3 edges_ok: node1 node2 node2 node3

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  • Complex Entity Framework linked-graphs issue: how to limit change set / break the graph?

    - by Hightechrider
    I have an EDMX containing Sentences, and Words, say and a Sentence contains three Words, say. Appropriate FK relationships exist between the tables. I create some words: Word word1 = new Word(); Word word2 = ... I build a Sentence: Sentence x = new Sentence (word1, word2, word3); I build another Sentence: Sentence y = new Sentence (word1, word4, word5); I try to save x to the database, but EF builds a change set that includes everything, including y, word4 and word5 that aren't ready to save to the database. When SaveChanges() happens it throws an exception: Unable to determine the principal end of the ... relationship. Multiple added entities may have the same primary key. I think it does this because Word has an EntityCollection<Sentence> on it from the FK relationship between the two tables, and thus Sentence y is inextricably linked to Sentence x through word1. So I remove the Navigation Property Sentences from Word and try again. It still tries to put the entire graph into the change set. What suggestions do the Entity Framework experts have for ways to break this connection. Essentially what I want is a one-way mapping from Sentence to Word; I don't want an EntityCollection<Sentence> on Word and I don't want the object graph to get intertwined like this. Code sample: This puts two sentences into the database because Verb1 links them and EF explores the entire graph of existing objects and added objects when you do Add/SaveChanges. Word subject1 = new Word(){ Text = "Subject1"}; Word subject2 = new Word(){ Text = "Subject2"}; Word verb1 = new Word(){ Text = "Verb11"}; Word object1 = new Word(){ Text = "Object1"}; Word object2 = new Word(){ Text = "Object2"}; Sentence s1 = new Sentence(){Subject = subject1, Verb=verb1, Object=object1}; Sentence s2 = new Sentence(){Subject=subject2, Verb=verb1, Object=object2}; context.AddToSentences(s1); context.SaveChanges(); foreach (var s in context.Sentences) { Console.WriteLine(s.Subject + " " + s.Verb + " " + s.Object); }

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  • Do you know of a free .Net component for visual flow model graph design and editing?

    - by Ivan
    An app (C#4, WinForms, Entity Framework, SQL Server 2008) of mine maintains a graph of interconnected objects, each having some simple member fields and a set of many directed (in and out) one-to-one links to other objects. I'd like to offer a user an ability to view and edit this graph visually some way, creating and removing connections, modifying objects attributes values and introducing/dropping objects. I suppose there has to be a framework (at list a primitive kind of) for this as visual model design tools are pretty common to meet. Do you know one?

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  • Facebook Graph API: Feed publishing showing up as link type instead of status?

    - by Redth
    So I'm publishing to a Facebook Group's Feed in my app, using the Graph API. It works fine, except facebook keeps treating the published info as a 'link' feed item type instead of 'status' like it does when I enter the same from facebook's site. eg: string url = "https://graph.facebook.com/<id-of-group/feed?access_token=<access-token>"; string data = "message=hello"; webClient.UploadString(url, "POST", data); Now when I pull the feed items, the json that is returned has "item":"link", with "link":"http://www.facebook.com", whereas I'd expect it to be "item":"status" and no or an empty "link" property. Any ideas?

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  • How i access the array of CGPoints to draw the graph?

    - by Rajendra Bhole
    Hi, I have the code in which i want to develop the graph.The code is, NSArray *coordinate = [[NSArray alloc] initWithObjects: @"42,213", @"75,173", @"108,153", @"141,133", @"174,113", @"207,73", @"240,33", nil]; CGContextSetRGBFillColor(ctx, 255, 0, 0, 1.0); CGContextSetLineWidth(ctx, 8.0); for(int intIndex = 0; intIndex < [coordinate count]; fltX1+=33, intIndex++) { CGContextMoveToPoint(ctx, fltX1+37, fltY2+18); CGPoint point = [[coordinate objectAtIndex:intIndex] CGPointValue]; CGContextAddLineToPoint(ctx, point); CGContextStrokePath(ctx); } The problem is that the function of CGContextAddLineToPoint(ctx, point); not working properly. How i drawing the line in the graph using above code????????

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  • How to upload a picture for an event using the Facebook Graph API?

    - by Thorarin
    I would like to know how to add a picture to an event using the Facebook Graph API. I have seen this question and tried some variations on that theme, without any success. The official documentation doesn't seem to make any mention of it. I'm using PHP for this particular project and I've looked at the PHP SDK source code, which is not helpful in any way. Requesting metadata for pictures using https://graph.facebook.com/eventid/picture?metadata=1&access_token... doesn't seem to be recognized, so no help there either. Has anyone come across some example or documentation on how to do this? (don't care about which language it is in)

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  • Flex Custom UIComponents

    - by user164142
    I have created a graph component in AS3 which extends UIComponent. I created an mxml component which is just a Label. The idea is to use the label component to show the values on the graph when you hover over points. I have tried two approaches. Create the Label component using ClassFactory inside the graph so it gets created in the graph component and addChild is called there. The problem is it is always 0 in size. Create in main mxml file and pass in to graph using a setter, the sizing is perfect but the x an y dont relate to my graph :( I suppose its similar to flex and itemrenderers, but in my case i have a graph and another component which can be changed, at the moment it is just a Label. Thanks Neil

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  • Makefile can not find boost libraries installed by macports

    - by user327502
    I just installed boost 1.42.0 from macports using sudo port install boost. Everything worked fine. Now I have a project that I'm trying to build using a makefile. Everything builds fine until it comes to the file that needs the boost library. It says: src/graph.h:20:42: error: boost/graph/adjacency_list.hpp: No such file or directory That file is actually located in two places: /opt/local/include/boost/graph/adjacency_list.hpp and /opt/local/var/macports/software/boost/1.42.0_0/opt/local/include/boost/graph/adjacency_list.hpp In the file src/graph.h where it's looking for boost/graph/adjacency_list.hpp, the include statement is here: #include<boost/graph/adjacency_list.hpp> How do I make this work?

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  • How do I post a link to the feed of a page via the Graph API *as* the page?

    - by jsdalton
    I'm working on a plugin for a Wordpress blog that posts a link to every article published to a Facebook Page associated with the blog. I'm using the Graph API and I have authenticated myself, for the time being, via OAuth. I can successfully post a message to the page using curl via a POST request to https://graph.facebook.com/{mypageid}/feed` with e.g. message = "This is a test" and it published the message. The problem is that the message is "from" my user account. I'm an admin on this test page, and when I go to Facebook and post an update from the web, the link comes "from" my page. Is there a way to authenticate myself as a page? Or is there an alternate way to POST to a page feed that doesn't end up being interpreted as a comment from a user? Thanks for any thoughts or suggestions.

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  • How can I make Excel correlate data from two data sets into a single graph?

    - by Tom Ritter
    I have two datasets, one being sparser than the other. They look like this: Data Set 1: 4 50 5 55 6 60 7 70 8 80 Data Set 2: 4 10 6 20 8 30 I have several hundred points instead of this few. I want them in the same graph, the X axis being 4-8, the y axis being 0-100ish, and two lines, one for each data set. What I get is two lines, not correlated at all along the X axis, and the X axis being labeled from one of the two datasets, with the labels being wrong for the other. The smaller data set is one-point-per-tick on the x axis, when I need it to skip ticks and actually line up with the other data set. Not married to excel, willing to try this in something else if it's free.

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  • Core Plot never stops asking for data, hangs device

    - by Ben Collins
    I'm trying to set up a core plot that looks somewhat like the AAPLot example on the core-plot wiki. I have set up my plot like this: - (void)initGraph:(CPXYGraph*)graph forDays:(NSUInteger)numDays { self.cplhView.hostedLayer = graph; graph.paddingLeft = 30.0; graph.paddingTop = 20.0; graph.paddingRight = 30.0; graph.paddingBottom = 20.0; CPXYPlotSpace *plotSpace = (CPXYPlotSpace*)graph.defaultPlotSpace; plotSpace.xRange = [CPPlotRange plotRangeWithLocation:CPDecimalFromFloat(0) length:CPDecimalFromFloat(numDays)]; plotSpace.yRange = [CPPlotRange plotRangeWithLocation:CPDecimalFromFloat(0) length:CPDecimalFromFloat(1)]; CPLineStyle *lineStyle = [CPLineStyle lineStyle]; lineStyle.lineColor = [CPColor blackColor]; lineStyle.lineWidth = 2.0f; // Axes NSLog(@"Setting up axes"); CPXYAxisSet *xyAxisSet = (id)graph.axisSet; CPXYAxis *xAxis = xyAxisSet.xAxis; // xAxis.majorIntervalLength = CPDecimalFromFloat(7); // xAxis.minorTicksPerInterval = 7; CPXYAxis *yAxis = xyAxisSet.yAxis; // yAxis.majorIntervalLength = CPDecimalFromFloat(0.1); // Line plot with gradient fill NSLog(@"Setting up line plot"); CPScatterPlot *dataSourceLinePlot = [[[CPScatterPlot alloc] initWithFrame:graph.bounds] autorelease]; dataSourceLinePlot.identifier = @"Data Source Plot"; dataSourceLinePlot.dataLineStyle = nil; dataSourceLinePlot.dataSource = self; [graph addPlot:dataSourceLinePlot]; CPColor *areaColor = [CPColor colorWithComponentRed:1.0 green:1.0 blue:1.0 alpha:0.6]; CPGradient *areaGradient = [CPGradient gradientWithBeginningColor:areaColor endingColor:[CPColor clearColor]]; areaGradient.angle = -90.0f; CPFill *areaGradientFill = [CPFill fillWithGradient:areaGradient]; dataSourceLinePlot.areaFill = areaGradientFill; dataSourceLinePlot.areaBaseValue = CPDecimalFromString(@"320.0"); // OHLC plot NSLog(@"OHLC Plot"); CPLineStyle *whiteLineStyle = [CPLineStyle lineStyle]; whiteLineStyle.lineColor = [CPColor whiteColor]; whiteLineStyle.lineWidth = 1.0f; CPTradingRangePlot *ohlcPlot = [[[CPTradingRangePlot alloc] initWithFrame:graph.bounds] autorelease]; ohlcPlot.identifier = @"OHLC"; ohlcPlot.lineStyle = whiteLineStyle; ohlcPlot.stickLength = 2.0f; ohlcPlot.plotStyle = CPTradingRangePlotStyleOHLC; ohlcPlot.dataSource = self; NSLog(@"Data source set, adding plot"); [graph addPlot:ohlcPlot]; } And my delegate methods like this: #pragma mark - #pragma mark CPPlotdataSource Methods - (NSUInteger)numberOfRecordsForPlot:(CPPlot *)plot { NSUInteger maxCount = 0; NSLog(@"Getting number of records."); if (self.data1 && [self.data1 count] > maxCount) { maxCount = [self.data1 count]; } if (self.data2 && [self.data2 count] > maxCount) { maxCount = [self.data2 count]; } if (self.data3 && [self.data3 count] > maxCount) { maxCount = [self.data3 count]; } NSLog(@"%u records", maxCount); return maxCount; } - (NSNumber *)numberForPlot:(CPPlot *)plot field:(NSUInteger)fieldEnum recordIndex:(NSUInteger)index { NSLog(@"Getting record @ idx %u", index); return [NSNumber numberWithInt:index]; } All the code above is in the view controller for the view hosting the plot, and when initGraph is called, numDays is 30. I realize of course that this plot, if it even worked, would look nothing like the AAPLot example. The problem I'm having is that the view is never shown. It finished loading because viewDidLoad is the method that calls initGraph above, and the NSLog statements indicate that initGraph finishes. What's strange is that I return a value of 54 from numberOfRecordsForPlot, but the plot asks for more than 54 data points. in fact, it never stops asking. The NSLog statement in numberForPlot:field:recordIndex prints forever, going from 0 to 54 and then looping back around and continuing. What's going on? Why won't the plot stop asking for data and draw itself?

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  • Best and easiest algorithm to search for a vertex on a Graph?

    - by Nazgulled
    Hi, After implementing most of the common and needed functions for my Graph implementation, I realized that a couple of functions (remove vertex, search vertex and get vertex) don't have the "best" implementation. I'm using adjacency lists with linked lists for my Graph implementation and I was searching one vertex after the other until it finds the one I want. Like I said, I realized I was not using the "best" implementation. I can have 10000 vertices and need to search for the last one, but that vertex could have a link to the first one, which would speed up things considerably. But that's just an hypothetical case, it may or may not happen. So, what algorithm do you recommend for search lookup? Our teachers talked about Breadth-first and Depth-first mostly (and Dikjstra' algorithm, but that's a completely different subject). Between those two, which one do you recommend? It would be perfect if I could implement both but I don't have time for that, I need to pick up one and implement it has the first phase deadline is approaching... My guess, is to go with Depth-first, seems easier to implement and looking at the way they work, it seems a best bet. But that really depends on the input. But what do you guys suggest?

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