store parent, child, grand- child data in memory

Question

I'm looking for the simplest method to store parent child data in memory for manipulation. There will be approx 100 parents, 20 children and 30 grand-children and only the number of parents will change, all child and grand-child properties will be known before compiling. I would like to access the grand children data using the parent ID and property name as a key. I could use a simple class with 200 odd properties, but I'm sure there's a more efficient method.

I've come across nested dictionaries/classes/structures/tuples, lists of lists, lists of arrays, json, non-binary trees etc but most posts are several years old and I'm not sure which method is best.

Please can anyone suggest which method to use or if there's a good library available?

    ID (1 to 100)
        |
        param 1   param 2   param 3  param 4.....param 20
        -val 1    -val 1   -val 1    -val 1      -val 1
        -val 2    -val 2   -val 2    -val 2      -val 2
        -val 3    -val 3   -val 3    -val 3      -val 3
        ...
        -val 30    -val 30   -val 30    -val 30      -val 30

Answer 1

I'd start with a simple, standard approach: define a class for a tree structure and use a list collection for the children nodes and a convenient contructor to assign a parent.

 public class Node
 {
     public List<Node> children = new List<Node>();

     public string Name;
     public int? Val;

     public Node Parent = null;

     public Node(string name, int? val, Node fromParent = null) {
         Name = name;
         Val = val;
         if (fromParent != null)
         {
             Parent = fromParent;
             fromParent.children.Add(this);
         }
     }

 }

A trivial usage:

var parent1 = new Node("parent1",10);
var child1 = new Node("child", 30, parent1);

Inheritance example

Subclasses

public class Root : Node
{
    public int ParentID;
    public Root(int id) : base(null, null, null)
    {
        ParentID = id;
    }
}

public class Parameter : Node
{
    public string ParameterType;
    public Parameter(string paramName, string paramType, Node fromParent = null) : base(paramName, null, fromParent)
    {
        ParameterType = paramType;
    }
}
public class Value : Node
{
    public string Unit;
    public Value(int val, string unit, Node fromParent = null) : base(null, val, fromParent)
    {
        Unit = unit;
    }
}

and how to instantiate them (with random values)

List<Node> parents = new List<Node>();
Random rnd = new Random();
for (int k = 0; k < 100; k++)
{
    var parentk = new Root(k);
    for (int kk = 0; kk < 20; kk++)
    {
        var paramkk = new Parameter("simple" + kk, "param1", parentk);
        for (int kkk = 0; kkk < 30; kkk++)
        {
            int dice = rnd.Next(1, 1000000);
            var valkkk = new Value(dice, "bar", paramkk);
        }

    }
    parents.Add(parentk);
}

in-memory searches

Let's say you have the above collection of parents and you want to find the one with max value for param1

DateTime start = DateTime.Now;
var mySearch = parents.SelectMany(x => x.children)
    .Where(x => ((Parameter)x).ParameterType == "param1")
  .GroupBy(x => x.Parent,
    x => x.children,
    (key, gr) =>
    new
    {
        Key = key,
        MaxVal = gr.Max(y => y.Max(z => z.Val))
    }).OrderByDescending(x => x.MaxVal).First();
var foundID = ((Root)mySearch.Key).ParentID;
DateTime stop  = DateTime.Now;

var elapsed = (stop - start).TotalMilliseconds;

and this search took about 15 milliseconds on my laptop

Answer 2

For this I would use an XML tree.

There are two options:

• XmlDocument serialization
• XDocument

XDocument is much simpler than using the other method. You can see the difference in this answer.

Here is a sample using XDocument:

var data =
    new XElement("root",
        new XElement("parent",
            new XElement("child",
                new XElement("grandchild"),
                new XElement("grandchild"),
                new XElement("grandchild"),
                //optionally you can add attributes such as Age or ID
                new XElement("grandchild", 
                    new XAttribute("Age","16"), new XAttribute("ID", "47"))
            )
        )
    );

You can than save and open it as an XML file like this:

var filePath = @"C:\XDocumentTest.xml";

using (var fileStream = new FileStream(filePath, FileMode.Create))
using (var writer = new StreamWriter(fileStream))
{
    writer.Write(data);
}
System.Diagnostics.Process.Start(filePath);

This is how the file would look like:

<root>
  <parent>
    <child>
      <grandchild />
      <grandchild />
      <grandchild />
      <grandchild Age="16" ID="47" />
    </child>
  </parent>
</root>