How to find an element through lists of list

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C#

class Node
{
string Name;
List<Node> NodeList=new List<Node>();
}

Here is my list,so each an every node contains list and name i need to iterate through all the lists to find out match my condition on any of the lists

What I have tried:

I tried foreach but i cant iterate through lists of list,any one give suggesiton.

C#

var element = (from sublist in node.NodeList
from item in sublist.NodeList
where item.Name == "Child 1 P3"
select item).FirstOrDefault();

it will traverse not depth only traversing for two lists,so i confused.

Posted 25-Feb-21 2:46am

Fazi_13

Updated 25-Feb-21 21:49pm

v2

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Comments

Richard MacCutchan 25-Feb-21 8:51am

Please show the code that you have tried, and indicate where it fails and why.

Fazi_13 25-Feb-21 8:55am

var element = (from sublist in node.NodeList
from item in sublist.NodeList
where item.Name == "Child 1 P3"
select item).FirstOrDefault();

it will traverse not depth only traversing for two lists,so i confused.

Patrice T 25-Feb-21 9:16am

Use Improve question to update your question.
So that everyone can pay attention to this information.

PIEBALDconsult 25-Feb-21 9:07am

Better to make an additional Dictionary to act as an index.
Or maybe you want a Hashset rather than List?

Fazi_13 25-Feb-21 9:10am

can you explain briefly

PIEBALDconsult 25-Feb-21 9:29am

Why are you using a list? Is the order of the elements critical?
Is searching for a Node within the List done frequently? Or only rarely?

Fazi_13 25-Feb-21 23:37pm

frequently i need to search it will depends upon my data.

PIEBALDconsult 26-Feb-21 9:08am

Then you need to build in a more efficient index -- don't "search".

2 solutions

Solution 1

If I duplicate what you say you have, it works:

C#

Node node = new Node() { Name = "Head" };
for (int i = 0; i < 5; i++)
    {
    Node subNode = new Node() { Name = $"Child {i} 0" };
    node.NodeList.Add(subNode);

    subNode.NodeList.Add(new Node() { Name = $"Child {i} P1" });
    subNode.NodeList.Add(new Node() { Name = $"Child {i} P2" });
    subNode.NodeList.Add(new Node() { Name = $"Child {i} P3" });
    }
var element = (from sublist in node.NodeList
               from item in sublist.NodeList
               where item.Name == "Child 1 P3"
               select item).FirstOrDefault();

element contains a single node, with the correct name: "Child 1 P3".

I'd start by using the debugger to check exactly what you have in node and all it's subnodes - because if it works with my code, it implies your data is not as you expect.

Posted 25-Feb-21 4:52am

OriginalGriff

Comments

Fazi_13 25-Feb-21 23:40pm

yes but my problem was if i have Child 1 P3 element in the depth list not in 2nd traverse list it will go depth that time it is failing

OriginalGriff 26-Feb-21 3:27am

While it is possible to use Linq to recurse, it's horribly messy.

You would be better off not trying to take a "Linq shortcut" but write a quick recursive method to look through a node and it's subnodes for a match instead.

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Maciej Los · Accepted Answer · 2021-02-25T21:49:00

Solution 2

You need recursion. See: c# - Find node when traversing tree - Stack Overflow[^]

Posted 25-Feb-21 21:49pm

Maciej Los