以线性表示形式获取方阵的主对角线

Question

我有代表方阵元素的 int 数组。我需要获取它的行、列、2 条主要对角线。我在获取第二个对角线时遇到了麻烦（对于 3*3 矩阵，对于 6*6 - 5,10,15,20,25,30，它是索引为 2,4,6 的元素）。我想知道是否有一种没有 for 循环的简洁方法。

        var matrix = new int[] { 6, 7, 2, 1, 5, 9, 8, 3, 4 };

        int size = 3;

        int i = 0;
        var rows = matrix.GroupBy(x => i++ / size);

        i = 0;
        var columns = matrix.GroupBy(x => i++ % size);

        var diag1 = matrix.Where((x, index)=>index%(size+1)==0);

        var diag2 = matrix.Where((x, index) => index % (size - 1) == 0);//PROBLEM - takes 0,8 indexes also.

Answer 1

试试这个

            var matrix = new int[] { 6, 7, 2, 1, 5, 9, 8, 3, 4 };

            int size = 3;

            var rows = matrix.Select((x,i) => new {x = x, i = i}).GroupBy(x => x.i / size).Select(x => x.Select(y => y.x).ToArray()).ToArray();

            var columns = matrix.Select((x, i) => new { x = x, i = i }).GroupBy(x => x.i % size).Select(x => x.Select(y => y.x).ToArray()).ToArray();

            var diag1 = matrix.Where((x, index) => (index /size) == (index % size)).Select(x => x).ToArray();

            var diag2 = matrix.Where((x, index) => (index / size) == (size - 1) - (index % size)).Select(x => x).ToArray();

以线性表示形式获取方阵的主对角线

getting main diagonal of square matrix in linear representation

c#

enumerable