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  • Python - Is there a better/efficient way to find a node in tree?

    - by Sej P
    I have a node data structure defined as below and was not sure the find_matching_node method is pythonic or efficient. I am not well versed with generators but think there might be better solution using them. Any ideas? class HierarchyNode(): def __init__(self, nodeId): self.nodeId = nodeId self.children = {} # opted for dictionary to help reduce lookup time def addOrGetChild(self, childNode): return self.children.setdefault(childNode.nodeId,childNode) def find_matching_node(self, node): ''' look for the node in the immediate children of the current node. if not found recursively look for it in the children nodes until gone through all nodes ''' matching_node = self.children.get(node.nodeId) if matching_node: return matching_node else: for child in self.children.itervalues(): matching_node = child.find_matching_node(node) if matching_node: return matching_node return None

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  • tic tac toe game ai as3

    - by David Jones
    I'm looking into creating a simple tic tac toe/noughts and crosses game in actionscript3 and am trying to understand the ideas behind the ai used in a game like this. I've seen some simplistic examples online but from what I've read a game tree or something like minimax is the best way to go about this. Can anyone help explain or reference any good examples of this? I've seen that there is a library called as3ds - data structures for game developers which has a number of classes that might help tie this together? Any info/examples or help is much appreciated

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  • Tic-Tac-Toe game AI

    - by David Jones
    I'm looking into creating a simple tic tac toe/noughts and crosses game in Actionscript3 and am trying to understand the ideas behind the AI used in a game like this. I've seen some simplistic examples online but from what I've read a game tree or something like minimax is the best way to go about this. Can anyone help explain or reference any good examples of this? I've seen that there is a library called as3ds - data structures for game developers which has a number of classes that might help tie this together? Any info/examples or help is much appreciated.

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  • Ray-Box Intersection during Scene traversal with matrix transforms

    - by Myx
    Hello: There are a few ways that I'm testing my ray-box intersections: Using the ComputeIntersectionBox(...) method, that takes a ray and a box as arguments and computes the closest intersection of the ray and the box. This method works by forming a plane with each of the faces of the box and finding an intersection with each of the planes. Once an intersection is found, a check is made whether or not the point is on the surface of the box by checking that the intersection point is between the corner points. When I look at rays after running this algorithm on two different boxes, I obtain the correct intersections. Using ComputeIntersectionScene(...) method without using the matrix transformations on a scene that has two spheres, a dodecahedron (a triangular mesh), and two boxes. ComputeIntersectionScene(...) recursively traverses all of the nodes of the scene graph and computes the closest intersection with the given ray. This test in particular does not apply any transformations that parent nodes may have that also need to be applied to their children. With this test, I also obtain the correct intersections. Using ComputeIntersectionScene(...) method WITH the matrix transformations. This test works like the one above except that before finding an intersection between the ray and a node in the scene, the ray is transformed into the node's coordinate frame using the inverse of the node's transformation matrix and after the intersection has been computed, this intersection is transformed back into the world coordinates by applying the transformation matrix to the intersection point. When testing with the third method on the same scene file as described in 2, testing with 4 rays (thus one ray intersects the one sphere, one ray the the other sphere, one ray one box, and one ray the other box), only the two spheres get intersected and the two boxes do not get intersections. When I debug looking into my ComputeIntersectionBox(...) method, it actually tells me that the ray intersects every plane on the box but each intersection point does not lie on the box. This seems to be strange behavior, since when using test 2 without transformations, I obtain the correct box intersections (thus, I believe my ray-box intersection to be correct) and when using test 3 WITH transformations, I obtain the correct sphere intersections (thus, I believe my transformed ray should be OK). Any suggestions where I could be going wrong? Thank you in advance.

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  • Problem building a complete binary tree of height 'h' in Python

    - by Jack
    Here is my code. The complete binary tree has 2^k nodes at depth k. class Node: def __init__(self, data): # initializes the data members self.left = None self.right = None self.data = data root = Node(data_root) def create_complete_tree(): row = [root] for i in range(h): newrow = [] for node in row: left = Node(data1) right = Node(data2) node.left = left node.right = right newrow.append(left) newrow.append(right) row = copy.deepcopy(newrow) def traverse_tree(node): if node == None: return else: traverse_tree(node.left) print node.data traverse_tree(node.right) create_complete_tree() print 'Node traversal' traverse_tree(root) The tree traversal only gives the data of root and its children. What am I doing wrong?

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  • Web Application Nat Traversal

    - by pbreault
    We are deploying web applications in java using tomcat on client machines across the country. Once they are installed, we want to allow a remote access to these web applications through a central server, but we do not want our clients to have to open ports on their routers. Is there a way to tunnel the http traffic in a way that the central server can access the web application that is behind the firewall ? The central server has a static ip address and we have full control over it. We don't need to access the filesystem, we only want to access the web application itself through a browser.

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  • XSD traversal in VIM

    - by maayank
    I use VIM as my text editor and I edit a lot of XML and WSDL files. WSDL files have an XSD section. Is there some VIM plugin I can use to traverse the XSD types? i.e., if I have the following line and the caret is where the '|' sign is: <xsd:element minOccurs="0" name="FooName" type="Magic|FooType"/> and I press Ctrl+Alt+Foo (or some other magic combo) it will get me to the definition of MagicFooType, i.e.: <xsd:complexType name="MagicFooType"> I couldn't find how to use ctags for this and all the other plugins that I could find are for imperative languages (i.e. Java). Is there some plugin/script to do the job?

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  • pyramid traversal resource url no attribute __name__

    - by Santana
    So I have: resources.py: def _add(obj, name, parent): obj.__name__ = name obj.__parent__ = parent return obj class Root(object): __parent__ = __name__ = None def __init__(self, request): super(Root, self).__init__() self.request = request self.collection = request.db.post def __getitem__(self, key): if u'profile' in key: return Profile(self.request) class Profile(dict): def __init__(self, request): super(Profile, self).__init__() self.__name__ = u'profile' self.__parent__ = Root self.collection = request.db.posts def __getitem__(self, name): post = Dummy(self.collection.find_one(dict(username=name))) return _add(post, name, self) and I'm using MongoDB and pyramid_mongodb views.py: @view_config(context = Profile, renderer = 'templates/mytemplate.pt') def test_view(request): return {} and in mytemplate.pt: <p tal:repeat='item request.context'> ${item} </p> I can echo what's in the database (I'm using mongodb), but when I provided a URL for each item using resource_url() <p tal:repeat='item request.context'> <a href='${request.resource_url(item)}'>${item}</a> </p> I got an error: 'dict' object has no attribute '__name__', can someone help me?

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  • Namespace Traversal

    - by RikSaunderson
    I am trying to parse the following sample piece of XML: <?xml version="1.0" encoding="UTF-8"?> <soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <soapenv:Body> <d2LogicalModel modelBaseVersion="1.0" xmlns="http://datex2.eu/schema/1_0/1_0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://datex2.eu/schema/1_0/1_0 http://datex2.eu/schema/1_0/1_0/DATEXIISchema_1_0_1_0.xsd"> <payloadPublication xsi:type="PredefinedLocationsPublication" lang="en"> <predefinedLocationSet id="GUID-NTCC-VariableMessageSignLocations"> <predefinedLocation id="VMS30082775"> <predefinedLocationName> <value lang="en">VMS M60/9084B</value> </predefinedLocationName> </predefinedLocation> </predefinedLocationSet> </payloadPublication> </d2LogicalModel> </soapenv:Body> </soapenv:Envelope> I specifically need to get at the contents of the top-level predefinedLocation tag. By my calculations, the correct XPath should be /soapenv:Envelope/soapenv:Body/d2LogicalModel/payloadPublication/predefinedLocationSet/predefinedLocation I am using the following C# code to parse the XML: string filename = "content-sample.xml"; XmlDocument xmlDoc = new XmlDocument(); xmlDoc.Load(filename); XmlNamespaceManager nsmanager = new XmlNamespaceManager(xmlDoc.NameTable); nsmanager.AddNamespace("soapenv", "http://schemas.xmlsoap.org/soap/Envelope"); string xpath ="/soapenv:Envelope/soapenv:Body/d2LogicalModel/payloadPublication/predefinedLocationSet/predefinedLocation"; XmlNodeList itemNodes = xmlDoc.SelectNodes(xpath, nsmanager); However, this keeps coming up with no results. Can anyone shed any light on this, because I feel like I'm banging my head on a brick wall.

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  • Multithreaded linked list traversal

    - by Rob Bryce
    Given a (doubly) linked list of objects (C++), I have an operation that I would like multithread, to perform on each object. The cost of the operation is not uniform for each object. The linked list is the preferred storage for this set of objects for a variety of reasons. The 1st element in each object is the pointer to the next object; the 2nd element is the previous object in the list. I have solved the problem by building an array of nodes, and applying OpenMP. This gave decent performance. I then switched to my own threading routines (based off Windows primitives) and by using InterlockedIncrement() (acting on the index into the array), I can achieve higher overall CPU utilization and faster through-put. Essentially, the threads work by "leap-frog'ing" along the elements. My next approach to optimization is to try to eliminate creating/reusing the array of elements in my linked list. However, I'd like to continue with this "leap-frog" approach and somehow use some nonexistent routine that could be called "InterlockedCompareDereference" - to atomically compare against NULL (end of list) and conditionally dereference & store, returning the dereferenced value. I don't think InterlockedCompareExchangePointer() will work since I cannot atomically dereference the pointer and call this Interlocked() method. I've done some reading and others are suggesting critical sections or spin-locks. Critical sections seem heavy-weight here. I'm tempted to try spin-locks but I thought I'd first pose the question here and ask what other people are doing. I'm not convinced that the InterlockedCompareExchangePointer() method itself could be used like a spin-lock. Then one also has to consider acquire/release/fence semantics... Ideas? Thanks!

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  • Balanced Search Tree Query, Asymtotic Analysis..

    - by AGeek
    Hi, The situation is as follows:- We have n number and we have print them in sorted order. We have access to balanced dictionary data structure, which supports the operations serach, insert, delete, minimum, maximum each in O(log n) time. We want to retrieve the numbers in sorted order in O(n log n) time using only the insert and in-order traversal. The answer to this is:- Sort() initialize(t) while(not EOF) read(x) insert(x,t); Traverse(t); Now the query is if we read the elements in time "n" and then traverse the elements in "log n"(in-order traversal) time,, then the total time for this algorithm (n+logn)time, according to me.. Please explain the follow up of this algorithm for the time calculation.. How it will sort the list in O(nlogn) time?? Thanks.

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  • Prototype - DOM Traversal with up()

    - by Jason McCreary
    I have the following structure: <form> <div class="content"> ... </div> <div class="action"> <p>Select <a class="select_all" href="?select=1" title="Select All">All</a></p> </div> </form> I am using Prototype's up() to traverse the DOM in order to find the <form> element in respect to the a.select_all. However the following doesn't work: select_link.up('form'); // returns undefined Yet, this does. select_link.up().up().up(); // returns HTMLFormElement Clearly this is an ancestor of a.select_all. The API Docs state Element.up() supports a CSSRule. What am I missing here?

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  • jquery - DOM traversal question

    - by David
    Hi, Basically what I have here is a button that adds a new list item to an unordered list. Within this list item is a dropdown box (.formSelector) that when changed triggers an ajax call to get the values for another dropdown box (.fieldSelector) in the same list item. The problem is on this line: $(this).closest(".fieldSelector").append( If I change it to $(".fieldSelector").append( the second box updates correctly. The problem with this is that when I have multiple list items it updates every dropdown box on the page with the class fieldSelector, which is undesirable. How can I traverse the DOM to just pick the fieldSelector in the current list item? Any help is greatly appreciated. Complete code: $("button", "#newReportElement").click(function() { $("#reportElements").append("<li class=\"ui-state-default\"> <span class=\"test ui-icon ui-icon-arrowthick-2-n-s \"></span><span class=\"ui-icon ui-icon-trash deleteRange \"></span> <select name=\"form[]\" class=\"formSelector\"><? foreach ($forms->result() as $row) { echo "<option value='$row->formId'>$row->name</option>"; }?></select><select class=\"fieldSelector\" name=\"field[]\"></select></li>"); $(".deleteRange").button(); $('.formSelector').change(function() { var id = $(this).val(); var url = "<? echo site_url("report/formfields");?>" + "/" + id; var atext = "ids:"; $.getJSON(url, function(data){ $.each(data.items, function(i,item){ $(this).closest(".fieldSelector").append( $('<option></option>').val(item.formId).html(item.formLabel) ); }); }); }); return false; });

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  • grid traversal question

    - by Kensay
    Given a grid of any height and width, write an algorithm to traverse it in a spiral. (Starting at the top left and ending in the middle) without passing over previously visited nodes. Without using nested loops.

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  • directory traversal in Java using different regular and enhanced for loops

    - by user3245621
    I have this code to print out all directories and files. I tried to use recursive method call in for loop. With enhanced for loop, the code prints out all the directories and files correctly. But with regular for loop, the code does not work. I am puzzled by the difference between regular and enhanced for loops. public class FileCopy { private File[] childFiles = null; public static void main(String[] args) { FileCopy fileCopy = new FileCopy(); File srcFile = new File("c:\\temp"); fileCopy.copyTree(srcFile); } public void copyTree(File file){ if(file.isDirectory()){ System.out.println(file + " is a directory. "); childFiles = file.listFiles(); /*for(int j=0; j<childFiles.length; j++){ copyTree(childFiles[j]); } This part is not working*/ for(File a: childFiles){ copyTree(a); } return; } else{ System.out.println(file + " is a file. "); return; } } }

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  • Are there any good Java/JVM libraries for my Expression Tree architecture?

    - by Snuggy
    My team and I are developing an enterprise-level application and I have devised an architecture for it that's best described as an "Expression Tree". The basic idea is that the leaf nodes of the tree are very simple expressions (perhaps simple values or strings). Nodes closer to the trunk will get more and more complex, taking the simpler nodes as their inputs and returning more complex results for their parents. Looking at it the other way, the application performs some task, and for this it creates a root expression. The root expression divides its input into smaller units and creates child expressions, which when evaluated it can use to build it's own result. The subdividing process continues until the simplest leaf nodes. There are two very important aspects of this architecture: It must be possible to manipulate nodes of the tree after it is built. The nodes may be given new input values to work with and any change in result for that node needs to be propagated back up the tree to the root node. The application must make best use of available processors and ultimately be scalable to other computers in a grid or in the cloud. Nodes in the tree will often be updating concurrently and notifying other interested nodes in the tree when they get a new value. Unfortunately, I'm not at liberty to discuss my actual application, but to aid understanding a little bit, you might imagine a kind of spreadsheet application being implemented with a similar architecture, where changes to cells in the table are propagated all over the place to other cells that need the result. The spreadsheet could get so massive that applying multi-core multi-computer distributed system to solve it would be of benefit. I've got my prototype "Expression Engine" working nicely on a single multi-core PC but I've started to run into a few concurrency issues (as expected because I haven't been taking too much care so far) so it's now time to start thinking about migrating the Engine to a more robust library, and that leads to a number of related questions: Is there any precedent for my "Expression Tree" architecture that I could research? What programming concepts should I consider. I realise this approach has many similarities to a functional programming style, and I'm already aware of the concepts of using futures and actors. Are there any others? Are there any languages or libraries that I should study? This question is inspired by my accidental discovery of Scala and the Akka library (which has good support for Actors, Futures, Distributed workloads etc.) and I'm wondering if there is anything else I should be looking at as well?

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  • WPF tree data binding

    - by Am
    Hi, I have a well defined tree repository. Where I can rename items, move them up, down, etc. Add new and delete. The data is stored in a table as follows: Index Parent Label Left Right 1 0 root 1 14 2 1 food 2 7 3 2 cake 3 4 4 2 pie 5 6 5 1 flowers 8 13 6 5 roses 9 10 7 5 violets 11 12 Representing the following tree: (1) root (14) (2) food (7) (8) flowers (13) (3) cake (4) (5) pie (6) (9) roeses (10) (11) violets (12) or root food cake pie flowers roses violets Now, my problem is how to represent this in a bindable way, so that a TreeView can handle all the possible data changes? Renaming is easy, all I need is to make the label an updatble field. But what if a user moves flowers above food? I can make the relevant data changes, but they cause a complete data change to all other items in the tree. And all the examples I found of bindable hierarchies are good for non static trees.. So my current (and bad) solution is to reload the displayed tree after relocation change. Any direction will be good. Thanks

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  • Binary Search Tree for specific intent

    - by Luís Guilherme
    We all know there are plenty of self-balancing binary search trees (BST), being the most famous the Red-Black and the AVL. It might be useful to take a look at AA-trees and scapegoat trees too. I want to do deletions insertions and searches, like any other BST. However, it will be common to delete all values in a given range, or deleting whole subtrees. So: I want to insert, search, remove values in O(log n) (balanced tree). I would like to delete a subtree, keeping the whole tree balanced, in O(log n) (worst-case or amortized) It might be useful to delete several values in a row, before balancing the tree I will most often insert 2 values at once, however this is not a rule (just a tip in case there is a tree data structure that takes this into account) Is there a variant of AVL or RB that helps me on this? Scapegoat-trees look more like this, but would also need some changes, anyone who has got experience on them can share some thougts? More precisely, which balancing procedure and/or removal procedure would help me keep this actions time-efficient?

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  • "Subforms" associated with tree view in VB

    - by knomdeguerre
    I am using VB Express 2008 to demonstrate my ideas for an improved UI for an existing product for my colleagues at work. The current UI has a certain page with ten tabs, allowing the user to define up to ten "things". The available choices for each of the ten "things" are all the same. On each of the ten tabs, there is a checkbox to enable that definition. Generally, a user will never use more than 5 or 6 unique definitions, the rest will remain disabled. So far, my prototype has a tree view control with one branch to contain this list of definitions, Add and Delete buttons. My idea is: there is one sub-branch to start with (corresponding to the first tab in the current UI); if the user wants addtional definitions, they click Add and other branches are added to the tree view, up to maximum of ten. I think I should be able to create a "class" that has a sub-UI (like a sub-form in Access) along with behavior code, that can be instantiated with each press of the Add button; each instantiation's settings can be set independently and is displayed in the main UI form )in a panel or frame) when selected in the tree view. For example, suppose the user Adds to make a total of three definitions: the tree view now has three sub-branches, each of which presents the same sub-UI with settings that can be set specific to the selected sub-branch. I'm sure it's possible but not sure how to do it. I know a comprehensive "answer" might be complicated and long, but I may just need some quick hints to get underway - don't be shy! Thanks in advance!

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  • WPF tree data binding model & repository

    - by Am
    Hi, I have a well defined tree repository. Where I can rename items, move them up, down, etc. Add new and delete. The data is stored in a table as follows: Index Parent Label Left Right 1 0 root 1 14 2 1 food 2 7 3 2 cake 3 4 4 2 pie 5 6 5 1 flowers 8 13 6 5 roses 9 10 7 5 violets 11 12 Representing the following tree: (1) root (14) (2) food (7) (8) flowers (13) (3) cake (4) (5) pie (6) (9) roeses (10) (11) violets (12) or root food cake pie flowers roses violets Now, my problem is how to represent this in a bindable way, so that a TreeView can handle all the possible data changes? Renaming is easy, all I need is to make the label an updatble field. But what if a user moves flowers above food? I can make the relevant data changes, but they cause a complete data change to all other items in the tree. And all the examples I found of bindable hierarchies are good for non static trees.. So my current (and bad) solution is to reload the displayed tree after relocation change. Any direction will be good. Thanks

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  • C# expression tree for ordinary code

    - by rwallace
    It's possible to create an expression tree, if you declare it as such. But is it possible to get an expression tree for an ordinary chunk of code such as a method or property getter? What I'm trying to do is, let's say for an order processing system, I have a class for order items: class Item : Entity { [Cascade] public Document document { get; set; } public int line { get; set; } public Product product { get; set; } public string description { get; set; } public decimal qty { get; set; } public decimal price { get; set; } public decimal net { get { return qty * price; } } public VatCode vat_code { get; set; } } where the net value equals qty * price, so I'd like to declare it as such, either with a property or method, and then also have the framework introspect that expression so it can generate appropriate SQL for defining a corresponding calculated column in a corresponding database view. The most obvious way to do this would be to get the expression tree for a property getter or a method, but I can't find any indication how to do this, or that it is possible. (I have found a way to get a method body as a byte stream, but that's not what's desired here.) If that isn't possible, I suppose the recommended solution would be to declare something like a static field that is an expression tree, and compile/run it at run time for internal use, and also introspect as normal for SQL generation?

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