Multiply key of the same dict

Question

I'm using python 3.5, I need to multiply this dict and this should output the result of multiplication of each key of dict.

{0: [0.0008726003490401396, 0.004363001745200698, 0.0008726003490401396, 0.0008726003490401396, 0.0017452006980802793, 0.008726003490401396, 0.0008726003490401396, 0.0017452006980802793, 0.0008726003490401396, 0.0017452006980802793, 0.0017452006980802793, 0.0008726003490401396, 0.0008726003490401396], 1: [0.007853403141361256, 0.008726003490401396, 0.0008726003490401396], 2: [0.004363001745200698, 0.0008726003490401396, 0.0008726003490401396, 0.0017452006980802793, 0.0008726003490401396, 0.0008726003490401396, 0.007853403141361256, 0.0008726003490401396, 0.0008726003490401396, 0.0008726003490401396, 0.002617801047120419, 0.0008726003490401396, 0.0008726003490401396, 0.0008726003490401396, 0.0017452006980802793, 0.0008726003490401396, 0.0008726003490401396, 0.0008726003490401396, 0.0017452006980802793, 0.0008726003490401396, 0.0008726003490401396, 0.0008726003490401396, 0.0008726003490401396, 0.0008726003490401396, 0.0008726003490401396, 0.008726003490401396, 0.0008726003490401396, 0.0008726003490401396, 0.0008726003490401396, 0.0008726003490401396, 0.0008726003490401396, 0.002617801047120419, 0.0008726003490401396, 0.0008726003490401396, 0.0017452006980802793, 0.0008726003490401396, 0.0008726003490401396, 0.0008726003490401396, 0.002617801047120419, 0.0034904013961605585, 0.0008726003490401396, 0.0008726003490401396, 0.0008726003490401396, 0.002617801047120419, 0.0008726003490401396, 0.0034904013961605585, 0.0008726003490401396, 0.0008726003490401396, 0.0008726003490401396, 0.0008726003490401396]}

This is my try but does not work:

lista = {k: [v*v for v in v] for k, v in lista.items()}

the output i would is for example:

{0: [0.068726003490401396], 1: [0.077853403141361256, 2: [0.098363001745200698]}

instead of inner list comprehension, look into python's 'reduce' function — matias elgart, Nov 13 '16 at 15:07

falsetru · Accepted Answer · 2016-11-13T15:16:46.340

3

Using dictionary comprehension and functools.reduce + operator.mul:

>>> from functools import mul
>>> mul(3, 4)  # == 3 * 4
12

>>> from functools import reduce
>>> reduce(mul, [3, 4, 2])  # == (3 * 4) * 2
24

>>> from functools import reduce
>>> from operator import mul
>>>
>>> lista = {
...     0: [0.0008726003490401396, 0.004363001745200698],
...     1: [0.007853403141361256, 0.008726003490401396, 0.0008726003490401396],
...     2: [0.004363001745200698, 0.0008726003490401396, 0.0008726003490401396],
... }
>>>
>>> {key: reduce(mul, value) for key, value in lista.items()}
{0: 3.8071568457248673e-06, 1: 5.979827506374137e-08, 2: 3.322126392430076e-09}
>>> {key: [reduce(mul, value)] for key, value in lista.items()}
{0: [3.8071568457248673e-06], 1: [5.979827506374137e-08], 2: [3.322126392430076e-09]}

edited Nov 13 '16 at 15:16

answered Nov 13 '16 at 15:11

falsetru

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thanks for the answer..but 0.0008726003490401396*0.004363001745200698= isn't the result of the moltiplication.. – Davide Di Menna Nov 13 '16 at 15:18
@DavideDiMenna, Then, could you elaborate how the expected values are calculated? – falsetru Nov 13 '16 at 15:23
you are right man! Now i try to do it.. Isn't a way without import? – Davide Di Menna Nov 13 '16 at 15:24
@DavideDiMenna, You can replace `mul` with `lambda a, b: a * b`. But reduce should be imported in Python 3.x. – falsetru Nov 13 '16 at 15:24
omg thank you man, im implementing a spam filter... I shoul reuse it :D The problem will be applay bayes function for each key of dict.. – Davide Di Menna Nov 13 '16 at 15:32
Thanks a lot.. But if want to mutiply each element of the list written by the function you wrote by a float? – Davide Di Menna Nov 13 '16 at 15:44
@DavideDiMenna, I don't understand what you mean. – falsetru Nov 13 '16 at 15:49
{0: [3.8071568457248673e-06], 1: [5.979827506374137e-08], 2: [3.322126392430076e-09]} all these element mutiplyed by 0.5 .. output would be {0: [3.8071568457248673e-06*0.5], 1: [5.979827506374137e-08*0.5], 2: [3.322126392430076e-09*0.5]} – Davide Di Menna Nov 13 '16 at 15:51
1

@DavideDiMenna, `reduce(..)` -> `reduce(..) * 0.5` seems what you want. – falsetru Nov 13 '16 at 16:07
i have done by my self now i should apply the bayes theorem with this method.. Impossibile that i could solve it.. Do you now how to sum two dictionaries? – Davide Di Menna Nov 13 '16 at 16:26

Multiply key of the same dict

1 Answers1