CODEWITHSUNDEEP
python
Serdar
Serdar

Reputation: 35

Generating full permutations of an integer sequence

I need to find a way (in python) to produce all permutations of integers of (+1)s and (-1)s according to given x legnth. For example if x=1, it should be [(+1),(-1)]; x = 2 -->[[(+1)(+1)],[(+1)(-1)],[(-1)(+1)],[(-1)(-1)]] and so on.

Actually, itertools.product() function does this work for string permutations. This is what I can do:

import itertools
def binary_sequence(k):
    L1 = [''.join(x) for x in itertools.product('+-', repeat=k)]
    L2 = list()
    for i in L1:
        L2.append([i])
    L2 = np.array(L2)
    return (L2)

However, I found no way to assign integers to strings afterwards. Is that possible to do this for integers using itertools or something else?

Upvotes: 0

Views: 59

Answers (2)

B. M.
B. M.

Reputation: 18628

You can really do string permutions :

In [338]: list(itertools.product(["-1","+1"],repeat=3))
Out[338]: 
[('-1', '-1', '-1'),
 ('-1', '-1', '+1'),
 ('-1', '+1', '-1'),
 ('-1', '+1', '+1'),
 ('+1', '-1', '-1'),
 ('+1', '-1', '+1'),
 ('+1', '+1', '-1'),
 ('+1', '+1', '+1')]

Upvotes: 1

Dani Mesejo
Dani Mesejo

Reputation: 61910

If I understood correctly you could do:

import itertools

import numpy as np


def binary_sequence(k):
    return np.array([x for x in itertools.product([-1, 1], repeat=k)])


for seq in binary_sequence(2):
    print(seq)

Output

[-1 -1]
[-1  1]
[ 1 -1]
[1 1]

The product function receives an iterable, from the documentation:

Cartesian product of input iterables.

Upvotes: 1

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