6 选择满足条件的矩阵行 在R中具有矩阵： one two three four [1,] 1 6 11 16 [2,] 2 7 12 17 [3,] 3 8 11 18 [4,] 4 9 11 19 [5,] 5 10 15 20 我要提取其行具有第三列= 11的子矩阵。即： one two three four [1,] 1 6 11 16 [3,] 3 8 11 18 [4,] 4 9 11 … 144 r select matrix submatrix