Python modifying List inside a dict-CodePudding

How to modify a dict of lists? for example: if I have a dict:

my_dict = {'numbers':[1,2,3],
'numbers2':[4,5,6]
'numbers3':[7,8,9]}

How do I, for example, do I multiply all numbers by 3? output:

my_dict = {'numbers':[3,6,9],
'numbers2':[12,15,18]
'numbers3':[21,24,27]}

CodePudding user response：

You just do it entry by entry.

for k in my_dict:
    my_dict[k] = [i*3 for i in my_dict[k]]

Note that I am creating a new list, rather than modifying the existing one in place.

CodePudding user response：

Tim's method is the easiest to understand if you're using raw Python lists. If you're using Numpy arrays, however, you could use a dict comprehension:

import numpy as np

my_dict = { "a": np.array([1, 2, 3]), "b": np.array([4, 5, 6]), "c": np.array([7, 8, 9]) }

my_dict = { k: v * 3 for k, v in my_dict.items() }