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c#.nettreepretty-print

How do I print out a tree structure?


I'm trying to improve performance in our app. I've got performance information in the form of a tree of calls, with the following node class:

public class Node
{
    public string Name; // method name
    public decimal Time; // time spent in method
    public List<Node> Children;
}

I want to print out the tree such that I can see lines between the nodes - something like in this question. What's an algorithm I can use in C# for doing that?

Edit: Obviously I need to use recursion - but my attempts keep putting the lines in the wrong places. What I'm asking for is a specific algorithm that will print the tree in a nice manner - the details of when to print a vertical line and when to print a horizontal one.

Edit: It isn't sufficient just to use copies of a string to indent the nodes. I'm not looking for

A
|-B
|-|-C
|-|-D
|-|-|-E
|-F
|-|-G

it has to be

A
+-B
| +-C
| +-D
|   +-E
+-F
  +-G

or anything similar, so long as the tree structure is visible. Notice that C and D are indented differently to G - I can't just use a repeated string to indent the nodes.


Solution

  • The trick is to pass a string as the indent and to treat the last child specially:

    class Node
    {    
       public void PrintPretty(string indent, bool last)
       {
           Console.Write(indent);
           if (last)
           {
               Console.Write("\\-");
               indent += "  ";
           }
           else
           {
               Console.Write("|-");
               indent += "| ";
           }
           Console.WriteLine(Name);
    
           for (int i = 0; i < Children.Count; i++)
               Children[i].PrintPretty(indent, i == Children.Count - 1);
       }
    }
    

    If called like this:

    root.PrintPretty("", true);
    

    will output in this style:

    \-root
      \-child
        |-child
        \-child
          |-child
          |-child
          \-child
            |-child
            |-child
            | |-child
            | \-child
            |   |-child
            |   |-child
            |   |-child
            |   \-child
            |     \-child
            |       \-child
            \-child
              |-child
              |-child
              |-child
              | \-child
              \-child
                \-child