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  • What is the most efficient way to determine if a directed graph is singly connected?

    - by zebraman
    I am working on an assignment where one of the problems asks to derive an algorithm to check if a directed graph G=(V,E) is singly connected (there is at most one simple path from u to v for all distinct vertices u,v of V. Of course you can brute force check it, which is what I'm doing right now, but I want to know if there's a more efficient way. Could anyone point me in the right direction?

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  • Good Java graph algorithm library?

    - by Nick Fortescue
    Has anyone had good experiences with any Java libraries for Graph algorithms. I've tried JGraph and found it ok, and there are a lot of different ones in google. Are there any that people are actually using successfully in production code or would recommend? To clarify, I'm not looking for a library that produces graphs/charts, I'm looking for one that helps with Graph algorithms, eg minimum spanning tree, Kruskal's algorithm Nodes, Edges, etc. Ideally one with some good algorithms/data structures in a nice Java OO API.

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  • need prefuse graph edges like arrows

    - by merve
    Hello, I did my homework and searched both google for a sample and a topic that is answered before on stackoverflow. But nothing has been found. My problem is ordinary edges who does not have a view like arrows. Here is what i do to hope there is forward arrows from target to destination: LabelRenderer nameLabel = new LabelRenderer("name"); nameLabel.setRoundedCorner(8, 8); DefaultRendererFactory rendererFactory = new DefaultRendererFactory(nameLabel); EdgeRenderer edgeRenderer; edgeRenderer = new EdgeRenderer(prefuse.Constants.EDGE_TYPE_LINE, prefuse.Constants.EDGE_ARROW_FORWARD); rendererFactory.setDefaultEdgeRenderer(edgeRenderer); vis.setRendererFactory(rendererFactory); Here is what i see about colour of edges, hoping these must not be transparent: int[] palette = new int[]{ColorLib.rgb(255, 180, 180), ColorLib.rgb(190, 190, 255)}; DataColorAction fill = new DataColorAction("socialnet.nodes", "gender", Constants.NOMINAL, VisualItem.FILLCOLOR, palette); ColorAction text = new ColorAction("socialnet.nodes", VisualItem.TEXTCOLOR, ColorLib.gray(0)); ColorAction edges = new ColorAction("socialnet.edges", VisualItem.STROKECOLOR, ColorLib.gray(200)); ColorAction arrow = new ColorAction("socialnet.edges", VisualItem.FILLCOLOR, ColorLib.gray(200)); ActionList colour = new ActionList(); colour.add(fill); colour.add(text); colour.add(edges); colour.add(arrow); vis.putAction("colour", colour); Thus, i wonder where am i wrong? Why my edges do not seem like arrows? Thanks for any idea. For more detail, i want to paste all of the code: /* * To change this template, choose Tools | Templates * and open the template in the editor. */ package prefusedeneme; import javax.swing.JFrame; import prefuse.data.*; import prefuse.data.io.*; import prefuse.Display; import prefuse.Visualization; import prefuse.render.*; import prefuse.util.*; import prefuse.action.assignment.*; import prefuse.Constants; import prefuse.visual.*; import prefuse.action.*; import prefuse.activity.*; import prefuse.action.layout.graph.*; import prefuse.controls.*; import prefuse.data.expression.Predicate; import prefuse.data.expression.parser.ExpressionParser; public class SocialNetworkVis { public static void main(String argv[]) { // 1. Load the data Graph graph = null; /* graph will contain the core data */ try { graph = new GraphMLReader().readGraph("socialnet.xml"); /* load the data from an XML file */ } catch (DataIOException e) { e.printStackTrace(); System.err.println("Error loading graph. Exiting..."); System.exit(1); } // 2. prepare the visualization Visualization vis = new Visualization(); /* vis is the main object that will run the visualization */ vis.add("socialnet", graph); /* add our data to the visualization */ // 3. setup the renderers and the render factory // labels for name LabelRenderer nameLabel = new LabelRenderer("name"); nameLabel.setRoundedCorner(8, 8); /* nameLabel decribes how to draw the data elements labeled as "name" */ // create the render factory DefaultRendererFactory rendererFactory = new DefaultRendererFactory(nameLabel); EdgeRenderer edgeRenderer; edgeRenderer = new EdgeRenderer(prefuse.Constants.EDGE_TYPE_LINE, prefuse.Constants.EDGE_ARROW_FORWARD); rendererFactory.setDefaultEdgeRenderer(edgeRenderer); vis.setRendererFactory(rendererFactory); // 4. process the actions // colour palette for nominal data type int[] palette = new int[]{ColorLib.rgb(255, 180, 180), ColorLib.rgb(190, 190, 255)}; /* ColorLib.rgb converts the colour values to integers */ // map data to colours in the palette DataColorAction fill = new DataColorAction("socialnet.nodes", "gender", Constants.NOMINAL, VisualItem.FILLCOLOR, palette); /* fill describes what colour to draw the graph based on a portion of the data */ // node text ColorAction text = new ColorAction("socialnet.nodes", VisualItem.TEXTCOLOR, ColorLib.gray(0)); /* text describes what colour to draw the text */ // edge ColorAction edges = new ColorAction("socialnet.edges", VisualItem.STROKECOLOR, ColorLib.gray(200)); ColorAction arrow = new ColorAction("socialnet.edges", VisualItem.FILLCOLOR, ColorLib.gray(200)); /* edge describes what colour to draw the edges */ // combine the colour assignments into an action list ActionList colour = new ActionList(); colour.add(fill); colour.add(text); colour.add(edges); colour.add(arrow); vis.putAction("colour", colour); /* add the colour actions to the visualization */ // create a separate action list for the layout ActionList layout = new ActionList(Activity.INFINITY); layout.add(new ForceDirectedLayout("socialnet")); /* use a force-directed graph layout with default parameters */ layout.add(new RepaintAction()); /* repaint after each movement of the graph nodes */ vis.putAction("layout", layout); /* add the laout actions to the visualization */ // 5. add interactive controls for visualization Display display = new Display(vis); display.setSize(700, 700); display.pan(350, 350); // pan to the middle display.addControlListener(new DragControl()); /* allow items to be dragged around */ display.addControlListener(new PanControl()); /* allow the display to be panned (moved left/right, up/down) (left-drag)*/ display.addControlListener(new ZoomControl()); /* allow the display to be zoomed (right-drag) */ // 6. launch the visualizer in a JFrame JFrame frame = new JFrame("prefuse tutorial: socialnet"); /* frame is the main window */ frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.add(display); /* add the display (which holds the visualization) to the window */ frame.pack(); frame.setVisible(true); /* start the visualization working */ vis.run("colour"); vis.run("layout"); } }

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  • Any implementations of graph st-ordering or ear-decomposition?

    - by chang
    I'm in the search for an implementation of an ear-decomposition algorithm (http://www.ics.uci.edu/~eppstein/junkyard/euler/ear.html). I examined networkx and didn't find one. Although the algorithm layout is vaguely in my mind, I'd like to see some reference implementation, too. I'm aware of Ulrik Brandes publication on a linear time Eager st-ordering algorithm, which results in an ear decomposition as a side product, if I understand correctly (it even includes pseudocode, which I'm trying to base my implementation on). Side problem: First step could be an st-ordering of a graph. Are there any implementations for st-ordering algorithms you know? Thanks for your input. I'd really like to contribute e.g. to networkx by implementing the ear-decomposition algorithm in python.

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  • Visual History for Chrome Maps Out Your Browser History in an Interactive Graph

    - by Jason Fitzpatrick
    Curious how your adventures on the web interweave? Visual History for Chrome maps out related web sites in your browsing history into an interactive chart–visualize your browsing over the last hours, days, or months. One of the interesting elements of Visual History is that it doesn’t simply link sites together via activated hyperlinks but by consecutive use within 20 minute increments–thus if you frequently hit up Gmail, Facebook, and Reddit first thing in the morning, they’ll all appear together in a usage cluster. Site can be organized by URL, sub-domain, or domain. Visual History is free, Chrome only. Visual History for Chrome [Chrome Web Store] HTG Explains: What The Windows Event Viewer Is and How You Can Use It HTG Explains: How Windows Uses The Task Scheduler for System Tasks HTG Explains: Why Do Hard Drives Show the Wrong Capacity in Windows?

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  • Adding graph in excel based on the content of ADFdi Table

    - by Arun
    Often we tend to represent the data present in the table in a graphical format to give a visual impression of the data. This article would be explaining the way to achieve it using the data we have in ADFdi table of the integrated workbook. Pre-requisites: Microsoft Office 2007 JDeveloper 11.1.1.1.0 and above Assuming we are already having an ADFdi enabled workbook with a table based on an Employee table as shown in the image below. Also, add the table.download to the ribbon toolbar as menu item / as action for the startup event. From excel, we'll add a new 3D bar chart Now, we need to select the data range for the chart. We will take an example of chart based on the salary of the employees. So, the data for the X-Axis of the chart would be the Ename and the data for the Y-Axis being the salary. We can do that by right clicking on the Chart and selecting Select Data. We would select the Legend Entry Series name as the Sal header column in the table, and for the data, we select both the header row and the row below it (by holding Shift key). And, for the Category Axis, we select the Ename header row and the row below it (by holding Shift key). We can get the chart now, by running the Workbook and downloading the data into the table. This simple example can be enhanced for complex graphs by using the data from the ADFdi table to use the power of excel along with ADF Desktop Integration.

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  • YouTube: Realtime Graph Sharing on the NetBeans Platform

    - by Geertjan
    Yet another really cool movie by the Maltego team in South Africa, this time showing Visual Library widgets in their NetBeans Platform application shared in realtime between different users of the Maltego open source intelligence gathering and analytics software: What you see above is Maltego CaseFile. Below you find out more about it in the latest blog entry on the Maltego site: http://maltego.blogspot.be/2013/11/maltego-casefile-v2-released.html

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  • Is programming or computer science in general, all about algorithms?

    - by wakandan
    As a grad student, I find it more and more common for prestigious companies (like Google, Facebook, Microsoft,...) to put algorithm questions in their test and interviews. A few startups I applied to also asked about algorithms. I wonder if algorithms fluency is the most important thing for software developer in those companies? If the answer being yes, what are the best method or resources for one to learn & practice about algorithms effectively? I can't seem to get interested in solving seemingly too complicated problems found in most textbook or websites. Though easily understand basic algorithms (like quicksort, bubblesort,...), I find it immensely difficult to remember and reuse them later. Thanks. P/S: If you ask me what I like, it's building good softwares to solve users' problems innovatively. I suppose that does not necessarily mean the software has to be very complicated.

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  • Facebook Open Graph - Grab how many times a page has been liked?

    - by DoMx
    I have a site that allows users to create a saying and then users "like" those sayings on Facebook. http://www.likeylikey.net/ I got a friend to throw up this simple code in less than 2 hours so it's basic. He knows little to nothing regarding the Open Graph API. Basically, I want to know how I can programmatically store how many times a page has been liked so I can list a "Top 10, most liked pages" list. Right now the index shows a list of all created pages and now I just wish to show the 10 most liked but I need a way of pulling that information from Facebook. Is this possible?

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  • Is there any way to validate the Open Graph protocol meta tags for Facebook integration?

    - by John
    Is there any way to validate the Facebook Open Graph protocol meta tags in the head section of my website? Code below. <meta property="og:title" content="my content" /> <meta property="og:type" content="company" /> <meta property="og:url" content="http://mycompany.com/" /> <meta property="og:image" content="http://mycompany.com/image.png" /> <meta property="og:site_name" content="my site name" /> <meta property="fb:admins" content="my_id" /> <meta property="og:description" content="my description" /> -edit- I mean validating the html. Sorry for the confusion! Right now my site isn't valid because of these tags.

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  • Fixed Resource Monitor Graph Scale in Windows Server 2008 R2

    - by Clever Human
    In Windows Server 2008 R2's Resource Monitor, is there a way to set the scale of the various graphs to be constant values instead of variable based on data? It seems to me that the utility of a graph is to get a quick overview glance at the values those graphs are showing. So if I look at the CPU graph and the line is up near the top, I can know immediately that something is using all my CPU and go investigate what. I don't really care if the CPU is jumping between .01% and 2%. Or if the network usage monitor is up near the top, I will know that all my bandwidth is being used up, and go figure out what. But the way things are now, the graphs are meaningless because the scales constantly shift. If you look at the network usage graph in one second it might have a scale out of 100kbps, and the next second have a scale based on 1mbps! So... is there a registry key or something that will peg the scale of these graphs to logical maximums?

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  • Scene graphs and spatial partitioning structures: What do you really need?

    - by tapirath
    I've been fiddling with 2D games for awhile and I'm trying to go into 3D game development. I thought I should get my basics right first. From what I read scene graphs hold your game objects/entities and their relation to each other like 'a tire' would be the child of 'a vehicle'. It's mainly used for frustum/occlusion culling and minimizing the collision checks between the objects. Spatial partitioning structures on the other hand are used to divide a big game object (like the map) to smaller parts so that you can gain performance by only drawing the relevant polygons and again minimizing the collision checks to those polygons only. Also a spatial partitioning data structure can be used as a node in a scene graph. But... I've been reading about both subjects and I've seen a lot of "scene graphs are useless" and "BSP performance gain is irrelevant with modern hardware" kind of articles. Also some of the game engines I've checked like gameplay3d and jmonkeyengine are only using a scene graph (That also may be because they don't want to limit the developers). Whereas games like Quake and Half-Life only use spatial partitioning. I'm aware that the usage of these structures very much depend on the type of the game you're developing so for the sake of clarity let's assume the game is a FPS like Counter-Strike with some better outdoor environment capabilities (like a terrain). The obvious question is which one is needed and why (considering the modern hardware capabilities). Thank you.

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  • Triangulating a partially triangulated mesh (2D)

    - by teodron
    Referring to the above exhibits, this is the scenario I am working with: starting with a planar graph (in my case, a 2D mesh) with a given triangulation, based on a certain criterion, the graph nodes are labeled as RED and BLACK. (A) a subgraph containing all the RED nodes (with edges between only the directly connected neighbours) is formed (note: although this figure shows a tree forming, it may well happen that the subgraph contain loops) (B) Problem: I need to quickly build a triangulation around the subgraph (e.g. as shown in figure C), but under the constraint that I have to keep the already present edges in the final result. Question: Is there a fast way of achieving this given a partially triangulated mesh? Ideally, the complexity should be in the O(n) class. Some side-remarks: it would be nice for the triangulation algorithm to take into account a certain vertex priority when adding edges (e.g. it should always try to build a "1-ring" structure around the most important nodes first - I can implement iteratively such a routine, but it's O(n^2) ). it would also be nice to reflect somehow the "hop distance" when adding edges: add edges first between the nodes that were "closer" to each other given the start topology. Nevertheless, disregarding the remarks, is there an already known scenario similar to this one where a triangulation is built upon a partially given set of triangles/edges?

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  • Graphical Interface and Object Selection/Manipulation

    - by ToriArendt
    I have a project I want to try to implement, but I'm kind of stuck on how to get started. I know there are probably a lot of resources that I can look at, but I'm really just stuck on what to even search for and where to begin. Basically, I have a program written in Java that separates 3D coordinates from a 3D reconstructed model into different objects. I then want to be able to perform a logistic regression on these objects to determine if they are type A or type B. But first, I need to classify a training set of objects as type A or B by hand. I don't know ANYTHING about graphing or user interfaces in Java, so I have been plotting the coordinates of a given object in MATLAB so that I can visualize the object and assign it a type. Now, as I am trying to make this program more "user friendly" I want to create an interface in Java where I can simply graph all the coordinates of the objects from the entire 3D model (on the same graph). I then want to be able to click on the each object and assign it to be either of type A or type B. I hope this description makes sense and someone can point me in the direction of something that will help me. I'm sorry if some of this terminology is off; I'm a bit new to software development. P.S. If anyone also has some tips on implementing logistic regression in Java, I'm sure I'll need them down the road :).

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  • How can I display the users profile pic using the facebook graph api?

    - by kielie
    Hi, I would like to display the users profile picture inside of my applications canvas page, is there a way to do that using the graph api? I know I can do it using FBML but I would also like to pass the profile pic to a flash game I am making, so I would have to get the profile pic from the api and send it as a variable, here is the code I have thus far, $facebook = new Facebook(array( 'appId' => FACEBOOK_APP_ID, 'secret' => FACEBOOK_SECRET_KEY, 'cookie' => true, 'domain' => 'myurl/facebook-test' )); $session = $facebook->getSession(); $uid = $facebook->getUser(); $me = $facebook->api('/me'); $updated = date("l, F j, Y", strtotime($me['updated_time'])); echo "Hello " . $me['name'] . $me['picture'] . "<br />"; echo "<div style=\"background:url(images/bg.jpg); width:760px; height:630px;\">" . "You last updated your profile on " . $updated . "</div>" . "<br /> your uid is" . $uid; Thanx in advance!

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