Examples of how to subtract a number to each element of a matrix in python using numpy:

Table of contents

### Using - operator

A solution is to use the - operator, example:

`>>> import numpy as np`

`>>> a = np.array(([1,2,3],[4,5,6],[7,8,9]))`

`>>> a`

`array([[1, 2, 3],`

`[4, 5, 6],`

`[7, 8, 9]])`

`>>> a = a - 1`

`>>> a`

`array([[0, 1, 2],`

`[3, 4, 5],`

`[6, 7, 8]])`

### Avec la function numpy subtract()

Another solution is to use the numpy function subtract

`>>> import numpy as np`

`>>> x1 = np.arange(9.0).reshape((3, 3))`

`>>> x1`

`array([[ 0., 1., 2.],`

`[ 3., 4., 5.],`

`[ 6., 7., 8.]])`

`>>> x2 = np.ones(9).reshape((3, 3))`

`>>> x2`

`array([[ 1., 1., 1.],`

`[ 1., 1., 1.],`

`[ 1., 1., 1.]])`

`>>> np.subtract(x1, x2)`

`array([[-1., 0., 1.],`

`[ 2., 3., 4.],`

`[ 5., 6., 7.]])`

### References

Links | Site |
---|---|

numpy.subtract | scipy doc |

Sum one number to every element in a list (or array) in Python | stackoverflow |

numpy.add | numpy doc |