如何过滤树形结构

本文关键字：结构 过滤 何过滤 | 更新日期: 2023-09-27 18:02:41

我有一个对象树MyNode:

public class MyNode
{
   public int Type { get; set; }
   public List<MyNode> Children { get; set; }
}
MyNode myRootNode;
// initializing a tree structure
所以我需要删除除 之外的所有节点

  1. 具有Type属性的节点等于int myType

  2. 在其子节点中包含具有Type属性的任何级别节点等于int myType的节点

我的方法:

bool Filter(MyNode node, MyNode parentNode, int type)
{
   bool isFound = false;
   if (node.Type == type)
      isFound = true; // There's type
   foreach (MyNode child in node.Children)
   {
      if (FilterTree(child, node, type))
          isFound = true; // There is child node who has this type
   }
   // If there aren't this type neither any of its children has it
   if (!isFound)
   {
      parentNode.Children.Remove(node);
   }
   return isFound;
}

我有一个例外:Collection was modified; enumeration operation may not execute.我认为这是因为我在列表中删除元素。有没有一种正确的方法?或者我做错了什么?

如何过滤树形结构

假设始终保留根节点，则可以删除方法中的子节点，而不是节点本身。

bool Filter(MyNode node,int type)
{
//remove children
foreach(MyNode child in node.Children.Where(c=>!Filter(c, type)).ToArray())
    node.Children.Remove(child);
//return if should be retained
return node.Type==type || node.Children.Count>0;
}

Linq来救你:

public static void RemoveNodesRecursive(this MyNode node, Predicate<MyNode> predicate)
{
    node.Children.RemoveAll(predicate);
    foreach (var n in node.Children)
    {
        RemoveNodes(n);
    }
}

然后从根节点开始:

myRootNode.RemoveNodesRecursive(n => n.node.Type == myType)
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