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• complicated graphviz tree structure

  - by thomas

  Hello. I am trying to create a tree structure with graphviz. I am open to either writing the graphviz code by hand or using the ruby-graphviz gem for ruby. Given the below picture can anyone provide any insight on the necessary code? Ignore that the lines are not straight...they should be when graphviz builds the graph. I am open to having dots/points when lines intersect as well. I have played with ruby-graphviz and the family tree class...this is getting me part of the way there but I really need all lines to be straight and intersect at right angles and the out-of-the-box code doesn't seem to do that.

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• JavaScript tree / treegrid libraries

  - by desau

  I'm looking for a good JavaScript tree / treegrid package. Now -- before you answer: It needs to be able to perform well with lots of nodes. Perhaps 1,000 sibling nodes. It needs to be able to draw to a usable state within 2 or 3 seconds with 1,000 nodes. It doesn't necessarily need to draw all 1,000 nodes at once -- if it supports some sort of "smart rendering" or fake scrolling. Beyond that, column resizing, drag and drop, inline editing would all be nice, although I could probably add that functionality myself. I've already tried dojo's tree and yahoo's YUI treeview. Both are too slow.

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• Build and render infinite hierarchical category tree from self-referential category table

  - by FreshCode

  I have a Categories table in which each category has a ParentId that can refer to any other category's CategoryId that I want to display as multi-level HTML list, like so: <ul class="tree"> <li>Parent Category <ul> <li>1st Child Category <!-- more sub-categories --> </li> <li>2nd Child Category <!-- more sub-categories --> </li> </ul> </li> </ul> Presently I am recursively rendering a partial view and passing down the next category. It works great, but it's wrong because I'm executing queries in a view. How can I render the list into a tree object and cache it for quick display every time I need a list of all hierarchical categories?

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• Is it easier to write a recursive-descent parser using an EBNF or a BNF?

  - by Vivin Paliath

  I've got a BNF and EBNF for a grammar. The BNF is obviously more verbose. I have a fairly good idea as far as using the BNF to build a recursive-descent parser; there are many resources for this. I am having trouble finding resources to convert an EBNF to a recursive-descent parser. Is this because it's more difficult? I recall from my CS theory classes that we went over EBNFs, but we didn't go over converting them into a recursive-descent parser. We did go over converting BNF's into a recursive-descent parser. The reason I'm asking is because the EBNF is more compact. From looking at the EBNF's in general, I notice that terms enclosed between { and } can be converted into a while loop. Are there any other guidelines or rules?

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• MS SQL server and Trees

  - by Julian

  Im looking for some way of extrating data form a tree table as defined below. Table Tree Defined as :- TreeID uniqueidentifier TreeParent uniqueidentifier TreeCode varchar(50) TreeDesc varchar(100) Data some (23k rows), Parent Refs back into ID in table The following SQL renders the whole tree (takes arround 2 mins 30) I need to do the following. 1) Render each Tree Node with its LVL 1 parent 2) Render all nodes that have a Description that matches a TreeDesc like 'SomeText%' 3) Render all parent nodes that are for a single tree id. Items 2 and 3 take 2mins30 so this needs to be a lot faster! Item 1, just cant work out how to do it with out killing SQL or taking forever any sugestions would be helpfull Thanks Julian WITH TreeCTE(TreeCode, TreeDesc, depth, TreeParent, TreeID) AS ( -- anchor member SELECT cast('' as varchar(50)) as TreeCode , cast('Trees' as varchar(100)) as TreeDesc, cast('0' as Integer) as depth, cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier) as TreeParent, cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier) as TreeID UNION ALL -- recursive member SELECT s.TreeCode, s.TreeDesc, cte.depth+1, isnull(s.TreeParent, cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier)), isnull(s.TreeID, cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier)) FROM pdTrees AS S JOIN TreeCTE AS cte ON isnull(s.TreeParent, cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier)) = isnull( cte.TreeID , cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier)) ) -- outer query SELECT s.TreeID, s.TreeCode, s.TreeDesc, s.depth, s.TreeParent FROM TreeCTE s

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• Bison: Optional tokens in a single rule.

  - by Simone Margaritelli

  Hi there .. i'm using GNU Bison 2.4.2 to write a grammar for a new language i'm working on and i have a question. When i specify a rule, let's say : statement : T_CLASS T_IDENT '{' T_CLASS_MEMBERS '}' { // create a node for the statement ... } If i have a variation on the rule, for instance statement : T_CLASS T_IDENT T_EXTENDS T_IDENT_LIST '{' T_CLASS_MEMBERS '}' { // create a node for the statement ... } Where (from flex scanner rules) : "class" return T_CLASS; "extends" return T_EXTENDS; [a-zA-Z\_][a-zA-Z0-9\_]* return T_IDENT; (and T_IDENT_LIST is a rule for comma separated identifiers). Is there any way to specify all of this only in one rule, setting somehow the "T_EXTENDS T_IDENT_LIST" as optional? I've already tried with T_CLASS T_IDENT (T_EXTENDS T_IDENT_LIST)? '{' T_CLASS_MEMBERS '}' { // create a node for the statement ... } But Bison gave me an error. Thanks

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• a general tree implementation in python

  - by vishnu

  i want to build a general tree in which a root node contains 'n' childrens and those childrens may contain other childrens.....

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• Code to apply expression tree directly to List

  - by Gamma Vega

  Is there a method call in Linq that will apply a expression tree directly on a List<V>? For instance, if I have a expression tree that is built on Order type, and i have a collection of List<Order> items on which i need to apply this expression. I am looking something similar to: class OrderListStore : IQueryable<V>, <other interfaces required to implement custom linq provider> { List<Order> orders; public Expression Expression { get { return Expression.Constant(this); } } IEnumerator<V> IEnumerable<V>.GetEnumerator() { //Here I need to have a method that will take the existing expression //and directly apply on list something like this .. Expression.Translate(orders); } } Any help in this regard is highly appreciated.

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• Code Golf Christmas Edition: How to print out a Christmas tree of height N

  - by TheSoftwareJedi

  Given a number N, how can I print out a Christmas tree of height N using the least number of code characters? N is assumed constrained to a min val of 3, and a max val of 30 (bounds and error checking are not necessary). N is given as the one and only command line argument to your program or script. All languages appreciated, if you see a language already implemented and you can make it shorter, edit if possible - comment otherwise and hope someone cleans up the mess. Include newlines and whitespace for clarity, but don't include them in the character count. A Christmas tree is generated as such, with its "trunk" consisting of only a centered "*" N = 3: * *** ***** * N = 4: * *** ***** ******* * N = 5: * *** ***** ******* ********* * N defines the height of the branches not including the one line trunk. Merry Christmas SO!

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• DevExpress>TcxDBTreeList Drag-Drop Tree Nodes (records)

  - by adnan

  I want to move tree nodes (db records) in TcxDBTreeList by dragging, is there a property on this component for this option ?

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• UVa #112 Tree Summing

  - by unclerojelio

  I'm working on UVa #112 Tree Summing. I have what I think should be a working solution but it is not accepted by the online judge due to a basic misunderstanding of the problem on my part. Consider the following inputs: -1 (-1()()) 77 (77(1()())()) or diagrammatically, the trees look like: -1 77 / \ / \ () () 1 () / \ () () According to at least two working solutions, the correct output for the above inputs is: yes no However, I don't understand why the second one should be 'no'. It looks to me like the rightmost path of the tree should give the proper sum. What am I missing?

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• Java or php tree structure problem

  - by agazerboy

  Hi All, I have all my data in my database. It has following 4 columns id source_clust target_clust result_clust 1 7 72 649 2 9 572 650 3 649 454 651 4 32 650 435 This data is like tree structure. source_clust and target_clust generate target_clust. target_clust can be source_clust or target_clust to make a new target_clust. Is there any php function or class that I can use to generate tree structure for my data???? I see this MySql site they are doing exactly what I need but I couldn't find how to implement that query in my data. Thanks ! Edited Is there any way in java to do it? if we have same data in array ??

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• Guidelines to an Iterator Class

  - by isurulucky

  Hi, I have a Red Black tree implemented in c++. It supports the functionality of a STL map. Tree nodes contain keys and the values mapped. I want to write an iterator class for this, but I'm stuck with how to do it. Should I make it an inner class of the Tree class? Can anyone give me some guidelines on how to write it + some resources?? Thank You!!

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• Looking for a better design: A readonly in-memory cache mechanism

  - by Dylan Lin

  Hi all, I have a Category entity (class), which has zero or one parent Category and many child Categories -- it's a tree structure. The Category data is stored in a RDBMS, so for better performance, I want to load all categories and cache them in memory while launching the applicaiton. Our system can have plugins, and we allow the plugin authors to access the Category Tree, but they should not modify the cached items and the tree(I think a non-readonly design might cause some subtle bugs in this senario), only the system knows when and how to refresh the tree. Here are some demo codes: public interface ITreeNode<T> where T : ITreeNode<T> { // No setter T Parent { get; } IEnumerable<T> ChildNodes { get; } } // This class is generated by O/R Mapping tool (e.g. Entity Framework) public class Category : EntityObject { public string Name { get; set; } } // Because Category is not stateless, so I create a cleaner view class for Category. // And this class is the Node Type of the Category Tree public class CategoryView : ITreeNode<CategoryView> { public string Name { get; private set; } #region ITreeNode Memebers public CategoryView Parent { get; private set; } private List<CategoryView> _childNodes; public IEnumerable<CategoryView> ChildNodes { return _childNodes; } #endregion public static CategoryView CreateFrom(Category category) { // here I can set the CategoryView.Name property } } So far so good. However, I want to make ITreeNode interface reuseable, and for some other types, the tree should not be readonly. We are not able to do this with the above readonly ITreeNode, so I want the ITreeNode to be like this: public interface ITreeNode<T> { // has setter T Parent { get; set; } // use ICollection<T> instead of IEnumerable<T> ICollection<T> ChildNodes { get; } } But if we make the ITreeNode writable, then we cannot make the Category Tree readonly, it's not good. So I think if we can do like this: public interface ITreeNode<T> { T Parent { get; } IEnumerable<T> ChildNodes { get; } } public interface IWritableTreeNode<T> : ITreeNode<T> { new T Parent { get; set; } new ICollection<T> ChildNodes { get; } } Is this good or bad? Are there some better designs? Thanks a lot! :)

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• Modifying JSF Component Tree in PhaseListener

  - by jamiebarrow

  Hi all, I'm having an issue. I've implemented a PhaseListener, which is meant to add a style class to any UIInput components in the tree that have messages attached to them, and removes the style class if it doesn't have any messages attached to them. The PhaseListener runs in the RENDER_RESPONSE phase, and does it's work in both the beforePhase and afterPhase methods while debugging. While debugging, I found that beforePhase doesn't have access to the full component tree, but afterPhase does. Any changes done in afterPhase aren't rendered though. How do I go about this? I want this to be completely server side. Thanks, James

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• Entropy using Decision Tree's

  - by Matt Clements

  Train a decision tree on the data represented by attributes A1, A2, A3 and outcome C described below: A1 A2 A3 C 1 0 1 0 0 1 1 1 0 0 1 0 For log2(1/3) = 1.6 and log2(2/3) = 0.6, answer the following questions: a) What is the value of entropy H for the given set of training example? b) What is the portion of the positive samples split by attribute A2? c) What is the value of information gain, G(A2), of attribute A2? d) What is IFTHEN rule(s) for the decision tree?

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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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• Precompile Lambda Expression Tree conversions as constants?

  - by Nathan

  It is fairly common to take an Expression tree, and convert it to some other form, such as a string representation (for example this question and this question, and I suspect Linq2Sql does something similar). In many cases, perhaps even most cases, the Expression tree conversion will always be the same, i.e. if I have a function public string GenerateSomeSql(Expression<Func<TResult, TProperty>> expression) then any call with the same argument will always return the same result for example: GenerateSomeSql(x => x.Age) //suppose this will always return "select Age from Person" GenerateSomeSql(x => x.Ssn) //suppose this will always return "select Ssn from Person" So, in essence, the function call with a particular argument is really just a constant, except time is wasted at runtime re-computing it continuously. Assuming, for the sake of argument, that the conversion was sufficiently complex to cause a noticeable performance hit, is there any way to pre-compile the function call into an actual constant?

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• "Arbitrary" context free grammars?

  - by danwroy

  Long time admirer first time inquirer :) I'm working on a program which derives a deterministic finite-state automata from a context-free grammar, and the paper I have been assigned which explains how to do this keeps referring to "arbitrary probabilistic context-free grammars" but never defines the meaning of "arbitrary" in relation to PCFGs. I assume they mean "any old PCFG" but then why not just say "any PCFG"? The term also turns up in several Wikipedia entries. At the top of the CFG page there is a reference to arbitrariness in relation to CFGs on ("clauses can be nested inside clauses arbitrarily deeply"), but doesn't make clear why someone would refer to a PCFG or subset of PCFGs as arbitrary. In case anyone is curious, the paper is Parsing and Hypergraphs by Klein and Manning (2001); I've also been reading two other papers by them related to this one (An Agenda-Based Chart Parser for Arbitrary Probabilistic Context-Free Grammars and Empirical Bounds, Theoretical Models, and the Penn Treebank) which use the term extensively but never explain it either. Thanks for your help!

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• View a git diff-tree in a reasonable format

  - by Josh

  Howdy, I'm about to do a git svn dcommit to our svn repo -- and as is recommended in a number of places, I wanted to figure out exactly what I was going to be committing with a dry run. As such I ran: git svn dcommit -n This produced output: Committing to http://somerepo/svn/branches/somebranch diff-tree 1b937dacb302908602caedf1798171fb1b7afc81~1 1b937dacb302908602caedf1798171fb1b7afc81 How do I view this in a format that I can consume as a human? A list of modified files comes to mind. This is probably easy, but running git diff-tree on those hashes gives me a reference to a directory and a some other hashes, as well as some numbers. Not quite sure what to make of it. Thanks very much, Josh

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• php tree structure problem

  - by agazerboy

  Hi All, I have all my data in my database. It has following 4 columns id source_clust target_clust result_clust 1 7 72 649 2 9 572 650 3 649 454 651 4 32 650 435 This data is like tree structure. source_clust and target_clust generate target_clust. target_clust can be source_clust or target_clust to make a new target_clust. Is there any php function or class that I can use to generate tree structure for my data???? I see this MySql site they are doing exactly what I need but I couldn't find how to implement that query in my data. Thanks !

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• are there any tree libraries/widgets for (n)curses

  - by phatmanace

  Hi - I wondered if there were any tree libraries available for (n)curses. I'm trying to write a component that shows a tree of folders & was curious if there was a prebuilt curses component that could do this. I've checked 'core' curses as well as libraries like CDK - and I can't seem to find anything. If none exists, I'm not averse to building my own - but I can't seem to locate any decent tutorials on doing this, so any help in this regard would also be much appreciated. Thanks, Ace

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• Binary Tree operator overloading and recursion

  - by furious.snail

  I was wondering how to overload the == operator for a binary tree to compare if two trees have identical data at same nodes. So far this is what I have: bool TreeType::operator==(const TreeType& otherTree) const { if((root == NULL) && (otherTree.root == NULL)) return true; //two null trees are equal else if((root != NULL) && (otherTree.root != NULL)) { return((root-info == otherTree.root-info) && //this part doesn't actually do anything recursively... //(root-left == otherTree.root-left) && //(root-right == otherTree.root-right)) } else return false; //one tree is null the other is not } I have a similar function that takes two TreeNode pointers as parameters but I've been stuck on how to convert it to this function.

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• Finding the largest subtree in a BST

  - by rakeshr

  Given a binary tree, I want to find out the largest subtree which is a BST in it. Naive approach: I have a naive approach in mind where I visit every node of the tree and pass this node to a isBST function. I will also keep track of the number of nodes in a sub-tree if it is a BST. Is there a better approach than this ?

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• what is a performance way to 'tree-walking' through my Entity Framework data

  - by Greg

  Hi, I have a Entity Framework design with a few tables that define a "graph". So there can be a large chain of relationships between objects in the few tables via concept of parent/child relationships. What is a performance way to 'tree-walking' through my Entity Framework data? That is I assume I wouldn't want to load the full set of all NODES and RELATIONSHIPS from the database for the purpose of walking the tree, where the end result may only be identifying leaf nodes? Or would this be OK with the way lazy loading may work at the column/parameter level? Else how could I load just the skeleton of the objects and then when needing to refer to any attributes have them lazy load then?

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