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  • In GWT-EXT checkboxtree how to handle single selection of tree nodes?

    - by RAS
    hi, I'm working on checkBoxTree in GWT-EXT 2.0.3 with Java. My aim is to get a selectionModel which allows me to select(check) only one TreeNode at a time. If I select another TreeNode after selecting one then, the previous one should be unchecked. I've tried using DefaultSelectionModel with TreePanel, but either I've not used it properly or it's working only for selection of TreeNode not for checking a TreeNode. Can anyone help me in this? Thanks in advance.

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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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  • Count in base 2, 3, 4 etc in Java and output all permutations

    - by tree-hacker
    I want to write a function in Java that takes as input an integer and outputs every possible permutation of numbers up to that integer. For example: f(1) 0 f(2) should output: 00 01 10 11 f(3) should output: 000 001 002 010 011 012 020 021 022 100 .... 220 221 222 That is it should output all 27 permutations of the digits of the numbers 0, 1, 2. f(4) should output 0000 0001 0002 0003 0010 ... 3330 3331 3332 3333 f(4) should output 00000 00001 ... 44443 44444 I have been trying to solve this problem but cannot seem to work out how to do it and keep getting confused by how many loops I need. Does anyone know how to solve this problem? Thanks in advance.

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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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  • What is the usage of Splay Trees in the real world?

    - by Meena
    I decided to learn about balanced search trees, so I picked 2-3-4 and splay trees. What are the examples of splay trees usage in the real world? In this Cornell: http://www.cs.cornell.edu/courses/cs3110/2009fa/recitations/rec-splay.html I read that splay trees are 'A good example is a network router'. But from rest of the explanation seams like network routers use hash tables and not splay trees since the lookup time is constant instead of O(log n).

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  • error while loading shared libraries, file too short

    - by tommyk
    From one of my customers I got an application. When I try to run it I got following error error while loading shared libraries: ./libvtkWidgets.so.5.4: file too short In my project structure I see following: -rwxrwxrwx 1 tomasz tomasz 20 2011-02-01 10:44 libvtkWidgets.so -rwxrwxrwx 1 tomasz tomasz 22 2011-02-01 10:44 libvtkWidgets.so.5.4 -rwxrwxrwx 1 tomasz tomasz 2147103 2011-02-01 10:44 libvtkWidgets.so.5.4.2 Is my shared library libvtkWidgets corrupted ? How to solve that error ?

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  • How is this number calculated?

    - by Hamid
    I have numbers; A == 0x20000000 B == 18 C == (B/10) D == 0x20000004 == (A + C) A and D are in hex, but I'm not sure what the assumed numeric bases of the others are (although I'd assume base 10 since they don't explicitly state a base. It may or may not be relevant but I'm dealing with memory addresses, A and D are pointers. The part I'm failing to understand is how 18/10 gives me 0x4. Edit: Code for clarity: *address1 (pointer is to address: 0x20000000) printf("Test1: %p\n", address1); printf("Test2: %p\n", address1+(18/10)); printf("Test3: %p\n", address1+(21/10)); Output: Test1: 0x20000000 Test2: 0x20000004 Test3: 0x20000008

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  • What is the usage of Spaly Trees in the real world?

    - by Meena
    I decided to learn about Balance search trees, so I picked 2-3-4 and splay trees. I'm wondering what are the examples of splay trees usage in the real world? In this Cornell: http://www.cs.cornell.edu/courses/cs3110/2009fa/recitations/rec-splay.html I read that splay trees are 'A good example is a network router'. But from rest of the explanation seams like network routers use hash tables and not splay trees since the lookup time is constant instead of O(log n). thanks!

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  • Adding multiple byte arrays in c# [migrated]

    - by James P. Wright
    I'm working on a legacy system that uses byte arrays for permission levels. Example: 00 00 00 00 00 00 00 01 means they have "Full Control" 00 00 00 00 00 00 00 02 means they have "Add Control" 00 00 00 00 00 00 00 04 means they have "Delete Control" So, if a User has "00 00 00 00 00 00 00 07" that means they have all 3 (as far as it has been explained to me). Now, my question is that I need to know how to get to "0x07" when creating/checking records. I don't know the syntax for actually combining 0x01, 0x02 and 0x04 so that I come out with 0x07.

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  • Running projects from NTFS partition on Ubuntu

    - by the_hamster
    I'm dual booting Windows 7/Ubuntu 12.04. I want to run C++/Java projects from a NTFS partition, where I keep generally all my files and projects. I fiddled with the fstab. One time I removed 'noexec', the other I changed it to 'exec'. After that,each time, I remounted the partition and it still didn't work. I tried using sudo mount -o remount,exec /media/mypartition It didn't work either. There was a somewhat similar question already, but it didn't have the proper answer for me or I didn't know how to make it work(note: I am a total newbie with Ubuntu and Linux in general).

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  • Fast language for problem solving? [closed]

    - by Friend of Kim
    I learned PHP to make websites. After some years I've started using programming for solving what is difficult tasks for my level. Now I want to make a program that solves equations. (I want to write it myself, not use an API. Because I'm doing this for the sake of the challenge, not for the result..) Because of this, I'm going to learn a new and faster/better language. It's going to be C++, Java, Python or C#. What are the benefits of each language, and which language is best for speed compared to speed of writing and readability? Using C would be lightning fast, but the lack of OO is making for more complex code and reduces the readability, for example..

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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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  • C# Process Binary File, Multi-Thread Processing

    - by washtik
    I have the following code that processes a binary file. I want to split the processing workload by using threads and assigning each line of the binary file to threads in the ThreadPool. Processing time for each line is only small but when dealing with files that might contain hundreds of lines, it makes sense to split the workload. My question is regarding the BinaryReader and thread safety. First of all, is what I am doing below acceptable. I have a feeling it would be better to pass only the binary for each line to the PROCESS_Binary_Return_lineData method. Please note the code below is conceptual. I looking for a but of guidance on this as my knowledge of multi-threading is in its infancy. Perhaps there is a better way to achieve the same result, i.e. split processing of each binary line. var dic = new Dictionary<DateTime, Data>(); var resetEvent = new ManualResetEvent(false); using (var b = new BinaryReader(File.Open(Constants.dataFile, FileMode.Open, FileAccess.Read, FileShare.Read))) { var lByte = b.BaseStream.Length; var toProcess = 0; while (lByte >= DATALENGTH) { b.BaseStream.Position = lByte; lByte = lByte - AB_DATALENGTH; ThreadPool.QueueUserWorkItem(delegate { Interlocked.Increment(ref toProcess); var lineData = PROCESS_Binary_Return_lineData(b); lock(dic) { if (!dic.ContainsKey(lineData.DateTime)) { dic.Add(lineData.DateTime, lineData); } } if (Interlocked.Decrement(ref toProcess) == 0) resetEvent.Set(); }, null); } } resetEvent.WaitOne();

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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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  • How to render all records from a nested set into a real html tree

    - by Christoph Schiessl
    I'm using the awesome_nested_set plugin in my Rails project. I have two models that look like this (simplified): class Customer < ActiveRecord::Base has_many :categories end class Category < ActiveRecord::Base belongs_to :customer # Columns in the categories table: lft, rgt and parent_id acts_as_nested_set :scope => :customer_id validates_presence_of :name # Further validations... end The tree in the database is constructed as expected. All the values of parent_id, lft and rgt are correct. The tree has multiple root nodes (which is of course allowed in awesome_nested_set). Now, I want to render all categories of a given customer in a correctly sorted tree like structure: for example nested <ul> tags. This wouldn't be too difficult but I need it to be efficient (the less sql queries the better). Update: Figured out that it is possible to calculate the number of children for any given Node in the tree without further SQL queries: number_of_children = (node.rgt - node.lft - 1)/2. This doesn't solve the problem but it may prove to be helpful.

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  • How to improve Minecraft-esque voxel world performance?

    - by SomeXnaChump
    After playing Minecraft I marveled a bit at its large worlds but at the same time I found them extremely slow to navigate, even with a quad core and meaty graphics card. Now I assume Minecraft is fairly slow because: A) It's written in Java, and as most of the spatial partitioning and memory management activities happen in there, it would naturally be slower than a native C++ version. B) It doesn't partition its world very well. I could be wrong on both assumptions; however it got me thinking about the best way to manage large voxel worlds. As it is a true 3D world, where a block can exist in any part of the world, it is basically a big 3D array [x][y][z], where each block in the world has a type (i.e BlockType.Empty = 0, BlockType.Dirt = 1 etc.) Now, I am assuming to make this sort of world perform well you would need to: A) Use a tree of some variety (oct/kd/bsp) to split all the cubes out; it seems like an oct/kd would be the better option as you can just partition on a per cube level not a per triangle level. B) Use some algorithm to work out which blocks can currently be seen, as blocks closer to the user could obfuscate the blocks behind, making it pointless to render them. C) Keep the block object themselves lightweight, so it is quick to add and remove them from the trees. I guess there is no right answer to this, but I would be interested to see peoples' opinions on the subject. How would you improve performance in a large voxel-based world?

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  • What is the best way to manage large 3d worlds (i.e minecraft style)?

    - by SomeXnaChump
    After playing minecraft I was marvelling a bit at their large worlds but at the same time finding it extremely slow to navigate, even with a quad core and meaty graphics card. Now I assume its fairly slow because: A) Its written in Java, and as most of the actual spatial partitioning and other memory management activities happen in there it would be slower than a native C++ version. B) They are not partitioning their world very well I could be wrong on both assumptions, however it got me thinking about the best way to manage large worlds. As it is more of a true 3d world, where a block can exist in any part of the world, it is basically a big 3d array [x][y][z], where each block in the world has a type (i.e BlockType.Empty = 0, BlockType.Dirt = 1 etc). Now I am assuming to make this sort of world performant you would need to: a) Use a tree of some variety (oct/kd/bsp) to split all the cubes out, it seems like an oct/kd would be the better option as you can just partition on a per cube level not a per triangle level. b) Use some algorithm to work out if the blocks within the scene can currently be seen, as blocks closer to the user could obfuscate the blocks behind, making it pointless to render them. c) Keep the block object themselves lightweight, so it is quick to add and remove them from the trees I guess there is no right answer to this, but I would be interested to see peoples opinions on the subject.

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