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How to find the number of permutations of a list of lists? - Printable Version

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How to find the number of permutations of a list of lists? - JoeB - Nov-18-2017



I have the following list:

list = [['A', 'M'], ['G', 'R'], ['T', 'E']]

I want to find the number of permutations of these letters, such that a letter from a sublist can only be used once.
In this case there are 2 x 2 x 2 = 8 possible permutations, namely: AGT, AGE, ARE, ART, MGT, MGE, MRT, MRE.

Attempt

I have been trying to use the itertools.permutations function. This was my first try:

list = [['A', 'M'], ['G', 'R'], ['E', 'T']]
pairs = [combo for combo in itertools.permutations(list, 3)]
print pairs
Output:
[(['A', 'M'], ['G', 'R'], ['E', 'T']), (['A', 'M'], ['E', 'T'], ['G', 'R']), (['G', 'R'], ['A', 'M'], ['E', 'T']), (['G', 'R'], ['E', 'T'], ['A', 'M']), (['E', 'T'], ['A', 'M'], ['G', 'R']), (['E', 'T'], ['G', 'R'], ['A', 'M'])]
As you can see, this is finding the number of permutations of the 3 sublists, which is not what I want.

Any ideas?

I want my output to look something like:

Output:
[['A', 'G', 'E'], ['A', 'R', 'E'], ... ]


RE: How to find the number of permutations of a list of lists? - heiner55 - Nov-18-2017

See https://python-forum.io/Thread-looking-for-code-combinations-of-letter-in-order

RE: How to find the number of permutations of a list of lists? - JoeB - Nov-18-2017

(Nov-18-2017, 05:44 PM)heiner55 Wrote: See https://python-forum.io/Thread-looking-for-code-combinations-of-letter-in-order

As shown in the question I'm pretty much already able to solve that problem. The problem in my question is different. It's about the cross-networking of sublists.

RE: How to find the number of permutations of a list of lists? - heiner55 - Nov-18-2017 

import itertools

list = [['A', 'M'], ['G', 'R'], ['E', 'T']]

for i in itertools.product(list[0], list[1], list[2]):
    print(i)
Output:
('A', 'G', 'E')
('A', 'G', 'T')
('A', 'R', 'E')
('A', 'R', 'T')
('M', 'G', 'E')
('M', 'G', 'T')
('M', 'R', 'E')
('M', 'R', 'T')


RE: How to find the number of permutations of a list of lists? - JoeB - Nov-18-2017

(Nov-18-2017, 06:10 PM)heiner55 Wrote: 
import itertools

list = [['A', 'M'], ['G', 'R'], ['E', 'T']]

for i in itertools.product(list[0], list[1], list[2]):
    print(i)
Output:
('A', 'G', 'E')
('A', 'G', 'T')
('A', 'R', 'E')
('A', 'R', 'T')
('M', 'G', 'E')
('M', 'G', 'T')
('M', 'R', 'E')
('M', 'R', 'T')

Thanks. Is there a more generalised form of this? So for example, I don't want to write list[0], list[1], list[2] because there might be more than 3.
(Nov-18-2017, 06:10 PM)heiner55 Wrote: 
import itertools

list = [['A', 'M'], ['G', 'R'], ['E', 'T']]

for i in itertools.product(list[0], list[1], list[2]):
    print(i)
Output:
('A', 'G', 'E')
('A', 'G', 'T')
('A', 'R', 'E')
('A', 'R', 'T')
('M', 'G', 'E')
('M', 'G', 'T')
('M', 'R', 'E')
('M', 'R', 'T')

Thanks. Is there a more generalised form of this? So for example, I don't want to write 
list[0], list[1], list[2]
because there might be more than 3.

RE: How to find the number of permutations of a list of lists? - heiner55 - Nov-18-2017 

import itertools
list = [['A', 'M'], ['G', 'R'], ['E', 'T']]
for i in itertools.product(*list):
    print(i)