ricardo - 1 year ago 100
Python Question

# term by term division in python (division termino a termino en python )

hello all, need to define a function that can be divided term by term matrix or in the worst cases, between arrays of lists so you get the result in a third matrix,

thanks for any response

Unless I'm misunderstanding, this is where `numpy` can be put to good use:

``````>>> from numpy import *
>>> a = array([[1,2,3],[4,5,6],[7,8,9]])
>>> b = array([[0.5] * 3, [0.5] * 3, [0.5] * 3])
>>> a / b
array([[  2.,   4.,   6.],
[  8.,  10.,  12.],
[ 14.,  16.,  18.]])
``````

This works for multiplication too. And indeed, as noted by Mark, scalar division (and multiplication) is also possible:

``````>>> a / 10.0
array([[ 0.1,  0.2,  0.3],
[ 0.4,  0.5,  0.6],
[ 0.7,  0.8,  0.9]])
>>> a * 10
array([[10, 20, 30],
[40, 50, 60],
[70, 80, 90]])
``````

Edit: to be complete, for lists of lists you could do the following:

``````>>> a = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
>>> b = [[0.5] * 3, [0.5] * 3, [0.5] * 3]
>>> def mat_div(a, b):
...     return [[n / d for n, d in zip(ra, rb)] for ra, rb in zip(a, b)]
...
>>> mat_div(a, b)
[[2.0, 4.0, 6.0], [8.0, 10.0, 12.0], [14.0, 16.0, 18.0]]
``````
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