MATLAB 用给定向量减去矩阵的每一行

Question

让

M = | 1 2 3 |
    | 4 5 6 |
    | 7 8 9 |

和

V = | 1 1 1 |

我想从 M 的每一行中减去 V，这样 M 应该看起来像

M = | 0 1 2 |
    | 3 4 5 |
    | 6 7 8 |

如果不使用 for，我如何做到这一点，有没有直接的命令？

Answer 1

>> M = [1 2 3; 4 5 6; 7 8 9];
>> V = [1 1 1];
>> MV = M-repmat(V,size(M,1),1)

MV =

     0     1     2
     3     4     5
     6     7     8

调用 repmat 将向量 V 重复 M 中的行数。

用户beaker pointed out that an even simpler (though a bit obscure) syntax works in recent versions of MATLAB. If you subtract a vector from a matrix, MATLAB will extend the vector to match the size of the matrix as long as one dimension of vector matches the matrix dimensions. See Compatible Array Sizes for Basic Operations。

>> M-V

ans =

     0     1     2
     3     4     5
     6     7     8

当然，如果知道V会包含全1，解法就更简单了：

>> MV = M-1

MV =

     0     1     2
     3     4     5
     6     7     8

Answer 2

您也可以使用bsxfun。

M = [1 2 3 ; 4 5 6 ; 7 8 9] ;
V = [1 1 1] ;
iwant = bsxfun(@minus,M,V)

MATLAB 用给定向量减去矩阵的每一行

MATLAB subtract every row of matrix by a given vector

matlab

matrix

subtraction