C# Sort List Based on Another List

Question

I have a class that has multiple List<> contained within it. Its basically a table stored with each column as a List<>. Each column does not contain the same type. Each list is also the same length (has the same number of elements).

For example:

I have 3 List<> objects; one List, two List, and three List.

//Not syntactically correct
List<DateTime> one = new List...{4/12/2010, 4/9/2006, 4/13/2008};
List<double> two = new List...{24.5, 56.2, 47.4};
List<string> three = new List...{"B", "K", "Z"};

I want to be able to sort list one from oldest to newest: one = {4/9/2006, 4/13/2008, 4/12/2010};

So to do this I moved element 0 to the end.

I then want to sort list two and three the same way; moving the first to the last.

So when I sort one list, I want the data in the corresponding index in the other lists to also change in accordance with how the one list is sorted.

I'm guessing I have to overload IComparer somehow, but I feel like there's a shortcut I haven't realized.

Answer 1

I hope this could help :

one = one.Sort(delegate(DateTime d1, DateTime d2)
{
    return Convert.ToDateTime(d2).CompareTo(Convert.ToDateTime(d1));
});

Answer 2

Here's a way to do it using LINQ and projections. The first query generates an array with the original indexes reordered by the datetime values; in your example, the newOrdering array would have members:

{ 4/9/2006, 1 }, { 4/13/2008, 2 }, { 4/12/2010, 0 }

The second set of statements generate new lists by picking items using the reordered indexes (in other words, items 1, 2, and 0, in that order).

var newOrdering = one
    .Select((dateTime, index) => new { dateTime, index })
    .OrderBy(item => item.dateTime)
    .ToArray();

// now, order each list
one = newOrdering.Select(item => one[item.index]).ToList();
two = newOrdering.Select(item => two[item.index]).ToList();
three = newOrdering.Select(item => three[item.index]).ToList();