python: create all possible unique lists with 1 or 0 of specific length

Question

I want to create all possible lists of binary vectors until a specified length, is there a better "pythonic" way to do this?

I used a recursive function of incrementing size:

def createAllBinHelper(length):
    def createAllBin(thelist, length):
        if length == 0:
            allpossibilities.append(thelist)
        else:
            createAllBin(thelist+'1', length-1)
            createAllBin(thelist+'0', length-1)

    allpossibilities = []

    for i in range(1,length):
        createAllBin('', i)

    return allpossibilities

You mean counting in binary? `for i in range(n): print(bin(i)[2:])` — msw, Apr 03 '16 at 02:17
@msw The only caveat is that the example output isn't in order (1, 0, 3, 2, 1, 0...), which may not matter. — Jared Goguen, Apr 03 '16 at 02:20

Jared Goguen · Answer 1 · 2016-04-03T02:17:07.557

1

You can combine a for loop with itertools.product.

from itertools import product

for i in range(1, 4):
    for p in product('10', repeat=i):
        print(''.join(p))

Changing the upper bound of range to n+1 will let you set the maximum length of the binary string.

This is the only current answer that produces your example output verbatim (which only matters if order matters).

edited Apr 03 '16 at 02:17

answered Apr 03 '16 at 02:09

Jared Goguen

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score 0 · Accepted Answer · answered Apr 03 '16 at 01:44

Maybe something like this might interest you

maxLength = 4
L = ['']
for n in range(maxLength):
    tmp = []
    for el in L:
        tmp.append(el+'0')
        tmp.append(el+'1')
        tmp.append('')
    L = tmp
L = sorted(set(L))
print(L)

output

['', '0', '00', '000', '0000', '0001', '001', '0010', '0011', '01', '010', '0100', '0101', '011', '0110', '0111', '1', '10', '100', '1000', '1001', '101', '1010', '1011', '11', '110', '1100', '1101', '111', '1110', '1111']

score 0 · Answer 3 · answered Apr 03 '16 at 01:55

Here is something else if you are feeling a bit bored

maxLength = 4
tmp = (2**maxLength)-1
s= ''
for n in range(1, tmp+1):
    s= ''
    while n>0:
        rem = n % 2
        n = int(n/2)
        s = s + str(rem)
    print(s)

this will give you the actual Binary combinations (without the all zeros).

Oh, yes, and output

python: create all possible unique lists with 1 or 0 of specific length

3 Answers3