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+--- Thread: permuting a list of lists (/thread-15509.html)
permuting a list of lists - Skaperen - Jan-20-2019
suppose i have a list of lists, where each inner list begins with its name followed by a sequence of numbers. i want to have nested loops that go though the numbers of each list in every combination. if i knew how many lists there are at coding time i could simply code that many nested loops. is there any combinatorical/permutation library/module/class/function that can go through all of these?
if there are 3 lists:
# for 3 lists:
for a in listoflists[0][1:]:
...
for b in listoflists[1][1:]:
...
for c in listoflists[2][1:]:
...
names = [n[0] for n in listoflists]
combos = [a,b,c]
...if there are 6 lists:# for 6 lists:
for a in listoflists[0][1:]:
...
for b in listoflists[1][1:]:
...
for c in listoflists[2][1:]:
...
for d in listoflists[3][1:]:
...
for e in listoflists[4][1:]:
...
for f in listoflists[5][1:]:
...
names = [n[0] for n in listoflists]
combos = [a,b,c,d,e,f]
...i did something like this ages ago but did it in assembly language. the code was ugly even for assembly. i later tried to code it in C but when i realized that to convert my assembler logic to C i'd end up having to code with gotos in several bad places, i gave up an used the old assembly version. now, i need to do the same kind of thing, again, and i no longer even have the assembly version. i'm hoping python has already worked out this kind of thing.i suppose i could flatten the list of lists. but the actual program needs to do things where flattening all the lists would not work. it really does need a variable amount of nesting of iterations with some of my code at every level.
RE: permuting a list of lists - ichabod801 - Jan-20-2019
It looks like you want itertools.product.
RE: permuting a list of lists - DeaD_EyE - Jan-20-2019
from random import randint
from itertools import product
products = [[randint(0, 255) for _ in range(5)] for _ in range(5)]
for prod in product(*products):
print(prod)