Array operations with n-dimensional array using LINQ (C#)

Question

Assume we have a jagged array

int[][] a = { new[] { 1, 2, 3, 4 }, new[] { 5, 6, 7, 8 }, new[] { 9, 10, 11, 12 } };

To get a sum of second row a

Answer 1

LINQ to Objects is based on the IEnumerable Interface, i.e. a one-dimensional sequence of values. This means it doesn't mix well with n-dimensional data structures like non-jagged arrays, although it's possible.

You can generate one-dimensional sequence of integers that index into the n-dimensional array:

int rowSum = Enumerable.Range(0, a.GetLength(1)).Sum(i => a[1, i]);

int colSum = Enumerable.Range(0, a.GetLength(0)).Sum(i => a[i, 1]);