tree-structure | 易学教程

Persistence: Data Trees stored as Directory Trees

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问题 I was wondering as to the practicalities of storing an in memory tree structure as directory tree for persistence purposes. In my case he target filesystem will be ZFS, and once the structure has been created it will be accessed by multiple processes infrequently. How performant is using a Directory Tree as a mechanism of persistence for Data Trees? 回答1: In order to read and write your tree, you will be calling the filesystem several times per node. This is much more expensive than any sane

SQL Server trigger (I need to move through a hierarchical tree structure from any given node)

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问题 Good day I have a legacy database that was designed for a specific front end application. I am doing multiples cases of additional app development using this data however, the legacy database has proven inadequate to work with going into the future. Unfortunately the legacy database has to stay in place due to the fact that i still need the front end application running. I have created a new database of similar structure that will be used, every time a vehicle (the example we'll use) is added

ObjectListView - TreeListView expand different lists in tree structure

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问题 I try to expand multiple lists in my tree structure. Let's say I have the following classes. I have the class Product, which contains a list with its children. This is my actual tree structure. class Product { int prodID; string prodName; List<Product> prodChildren; List<Article> articleList; //maybe further list... public int ProdID { get { return prodID;} set{prodID = value;} } public string ProdName { get { return prodName;} set {prodName = value;} } public Product(int id, string name) {

Dynamic Javascript Tree Structure

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问题 I would like to build the hierarchy dynamically with each node created as a layer/level in the hierarchy having its own array of nodes. THIS SHOULD FORM A TREE STRUCTURE.There should be a root node, and an undefined number of nodes and levels to make up the hierarchy size. Nothing should be fixed besides the root node. I do not need to read or search the hierarchy, I need to construct it. The array should start {"name" : "A", "children" : []} and every new node as levels would be created {

Where does scikit-learn hold the decision labels of each leaf node in its tree structure?

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问题 I have trained a random forest model using scikit-learn and now I want to save its tree structures in a text file so I can use it elsewhere. According to this link a tree object consist of a number of parallel arrays each one hold some information about different nodes of the tree (ex. left child, right child, what feature it examines,...) . However there seems to be no information about the class label corresponding to each leaf node! It's even not mentioned in the examples provided in the

Recursive search on a collection in MongoDB

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问题 I have a list of documents in MongoDB with tree structure, where Model Tree Structures with Parent References pattern used. I want a single aggregation query which returns ancestor list(till the root), given the 'name' property. Structure: { '_id': '1', 'name': 'A', 'parent': '', }, { '_id': '2', 'name': 'B', 'parent': 'A', }, { '_id': '3', 'name': 'C', 'parent': 'B', }, { '_id': '4', 'name': 'D', 'parent': 'C', } Aggregation result:(Given, name = 'D') { '_id': '4', 'name': 'D', 'ancestors':

Create Object in Every Loop Iteration

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问题 I am using z80 navigation control that's built-in and here is the link for demonstration: Z80 Navigation Menu If anyone see the control, it has an object to create menus like parent menus and under it, child menus. Something like the following: public List<NavBarItem> sampleDynamicNav; //List of navbar objects public DemoItems() { //Create object instance here and assign the parent as well child menus here sampleDynamicNav = new List<NavBarItem> { new NavBarItem {ID = 1, Text = "UserInfo",

Django CMS Multi-Level Dropdown Menu

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问题 Im kinda new to Django CMS and im trying my best to avoid asking, but this one drives me crazy. I made a Wiki app with a Topic, and Category model. I hooked it to a Site on my CMS and added it to my Menu. Now i would like to be able to show all Top-Level categories, their Child Categories & Topics, and the Child categories of these, and so on, on my menu. Menu/Navigation should look like this: Wiki Category1 Category1.1 Topic Category1.2 Topic Category2 Topic Category3 ... Right now i can

Sencha Touch 2: Insert into TreeStore/NestedList

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问题 I'm using a NestedList with a underlying TreeStore. Now I want to add items to the NestedList as leafs. How can I do this? Currently my code (Controller, onAddButtonTapped) looks like this: var store = Ext.getStore('menuStore'); var customerAreaNode = store.getRoot().getChildAt(1); customerAreaNode.appendChild({name: "text", leaf:true}); customerAreaNode.expand(); store.sync(); This code results in two new empty listentries on leaf level (behind the correct node) and one new listentry on node

Django CMS Multi-Level Dropdown Menu

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Im kinda new to Django CMS and im trying my best to avoid asking, but this one drives me crazy. I made a Wiki app with a Topic, and Category model. I hooked it to a Site on my CMS and added it to my Menu. Now i would like to be able to show all Top-Level categories, their Child Categories & Topics, and the Child categories of these, and so on, on my menu. Menu/Navigation should look like this: Wiki Category1 Category1.1 Topic Category1.2 Topic Category2 Topic Category3 ... Right now i can only show the Top categories: Wiki Category1 Category2 Category3 I Already created a menu.py to get a