What is the code to return all possible subsets of an array using python??

Answer 1

But how can it be implemented without using built in functions?

Answer 2

I'm assuming that you mean "list" instead of array.... :)

If you want all subsets of length 3:

import itertools
mylist = [1,2,3,4,5]
for subset in itertools.combinations(mylist,3):
print(subset)

If you want all possible subsets (the so-called "powerset"):

import itertools
mylist = [1,2,3,4,5]
for subset_size in range(len(mylist)):
for subset in itertools.combinations(mylist,subset_size+1):
print(subset)

Answer 3

First, a question - why? Why reinvent the wheel when you already have (probably much better optimized) code that does it?

As for the answer - I think the easiest way to do it is recursively (at each step, try and select another one of the remaining elements in the list, until you reach a predefined length).

Answer 4

And if the answer to my "why" is "because my homework requires me not to use any built-in functions", you're in the wrong place.... :)