C＃将元组列表拆分为多个列表

Question

Assuming I have the following list of tuples:

List<Tuple<string, string>>

{"Name", "xx"},{"Age", "25"},{"PostalCode", "12345"},{"Name", "yy"},{"Age", "30"},{"PostalCode", "67890"}

I want to split this list into multiple lists. Splitting criteria is Item1 == "Name"

Result should be following:

List 1:

{"Name", "xx"},{"Age", "25"},{"PostalCode", "12345"}

List 2:

{"Name", "yy"},{"Age", "30"},{"PostalCode", "67890"}

I have a solution where I note down the indexes of "Name" in the original list and create new lists by using the function GetRange . But there must be a better and faster way of doing this?

Answer 1

You can use LINQ to find all the indices of Name and select it and the following 3 entries into a new list.

This assumes that the original list is well-formed such that for every Name there is guaranteed to be two valid fields following it.

var data = new List<Tuple<string, string>>
{
    new Tuple<string, string>("Name", "xx"),
    new Tuple<string, string>("Age", "25"),
    new Tuple<string, string>("PostalCode", "12345"),
    new Tuple<string, string>("ignoreMe", "345"),
    new Tuple<string, string>("Name", "yy"),
    new Tuple<string, string>("Age", "30"),
    new Tuple<string, string>("PostalCode", "67890")
};

var lists = data
    .Select((x, i) => new { Index = i, Value = x })
    .Where(x => x.Value.Item1 == "Name")
    .Select(x => data.Skip(x.Index).Take(3))
    .ToList();

And also, there are probably more performant solutions than this.

Answer 2

You can use Enumrable.Range to loop trough your list and select your desired tuples:

List<Tuple<string, string>> data = new List<Tuple<string, string>>
{
    new Tuple<string, string>("Name", "xx"),
    new Tuple<string, string>("Age", "25"),
    new Tuple<string, string>("PostalCode", "12345"),
    new Tuple<string, string>("Name", "yy"),
    new Tuple<string, string>("Age", "30"),
    new Tuple<string, string>("PostalCode", "67890")
};

var result = Enumerable.Range(0, data.Count).Where(i => data[i].Item1 == "Name")
            .Select(i => data.Skip(i).Take(3).ToList())
            .ToList();

You can test my code here : https://dotnetfiddle.net/6fJumx