Fetch (x,y) from a 2D Array where condition matches

Question

This is 2D array:

int[][] array2D = new int[7][];
for (int i = 0; i < 7; i++)
    array2D[i] = new int[7];

How can I turn the following into a LINQ query, or use enumerable methods to achieve the same output?

var lst = new List<Point>();

for (int r = 0; r < array2D.Length; r++)
    for (int c = 0; c < array2D[r].Length; c++)
        if (array2D[r][c] == 0)
            lst.Add(new Point(c, r));

EDIT - Solution based on @'King King's answer

var lst = m_boardArr.SelectMany((row, rowIndex) =>
            row.Select((val, colIndex) =>
                new { val, point = new Point(colIndex, rowIndex) })
                   .Where(col => col.val == 0)
                   .Select(col => col.point)).ToList();

Answer 1

Try this:

var lst = array2D.SelectMany((x,r) => x.Select((a,c)=> new {a,b=new Point(c,r)})
                                       .Where(a=>a.a==0)
                                       .Select(a=>a.b)).ToList();

Answer 2

The trick is to use the Select and SelectMany that capture the loop variables into an anonymous type, then get those properties back later after the Where clause, thus:

var list = array2D
    .SelectMany((row, r) => row
        .Select((el, c) => 
        new {Element = el, ColIndex = c, RowIndex = r})
        .Where(thing => thing.Element == 0)
        .Select(thing => new Point(thing.RowIndex, thing.ColIndex)))
    .ToList();

EDIT: Bartosz's comment applies to this solution as well. Unreadable!

Answer 3

var lst = array2D
    .SelectMany((innerArray, r)
        => Enumerable
               .Range(0, innerArray.Length)
               .Where(c => innerArray[c] == 0)
               .Select(c => new Point(c, r)))
    .ToList();

However, your current solution is more readable.