Python program to find all the Combinations in the list with the given condition

Given a list with some elements being a list of optional elements. The task is to find all the possible combinations from all options.

Examples:

Input: test_list = [1,2,3] 
Output: 
 [1], [1, 2], [1, 2, 3], [1, 3]
 [2], [2, 3], [3]

Example 1: Get all possible combinations of a list’s elements using combinations

Python3

from itertools import combinations
# initializing list
test_list = ["GFG", [5, 4], "is",
            ["best", "good", "better", "average"]]
idx=0
temp = combinations(test_list, 2)
for i in list(temp):
    idx = idx+1
    print ("Combination", idx, ": ", i)

Output:

Combination 1 :  ('GFG', [5, 4])
Combination 2 :  ('GFG', 'is')
Combination 3 :  ('GFG', ['best', 'good', 'better', 'average'])
Combination 4 :  ([5, 4], 'is')
Combination 5 :  ([5, 4], ['best', 'good', 'better', 'average'])
Combination 6 :  ('is', ['best', 'good', 'better', 'average'])

Example 2: Get all possible combinations of a list’s elements using combinations_with_replacement

Python3

from itertools import combinations_with_replacement

# initializing list
test_list = ["GFG", [5, 4], "is",
            ["best", "good", "better", "average"]]
idx=0
temp = combinations_with_replacement(test_list, 2)
for i in list(temp):
    idx = idx+1
    print ("Combination", idx, ": ", i)

Output:

Combination 1 :  ('GFG', 'GFG')
Combination 2 :  ('GFG', [5, 4])
Combination 3 :  ('GFG', 'is')
Combination 4 :  ('GFG', ['best', 'good', 'better', 'average'])
Combination 5 :  ([5, 4], [5, 4])
Combination 6 :  ([5, 4], 'is')
Combination 7 :  ([5, 4], ['best', 'good', 'better', 'average'])
Combination 8 :  ('is', 'is')
Combination 9 :  ('is', ['best', 'good', 'better', 'average'])
Combination 10 :  (['best', 'good', 'better', 'average'], ['best', 'good', 'better', 'average'])

Example 3: Get all possible combinations of a list’s elements using loop

In this, we use a nested loop to get index wise combinations from each nested option list, and then the outer loop is used to get default values in all combinations.

Python3

def combinations(iterable, r):
    pool = tuple(iterable)
    n = len(pool)
    if r > n:
        return
    indx = list(range(r))
    yield tuple(pool[i] for i in indx)
    while True:
        for i in reversed(range(r)):
            if indx[i] != i + n - r:
                break
        else:
            return
        indx[i] += 1
        for j in range(i+1, r):
            indx[j] = indx[j-1] + 1
        yield tuple(pool[i] for i in indx)


x = [2, 3, 1, 6, 4, 7]
for i in combinations(x, 2):
    print(i)

Output:

(2, 3)
(2, 1)
(2, 6)
(2, 4)
(2, 7)
(3, 1)
(3, 6)
(3, 4)
(3, 7)
(1, 6)
(1, 4)
(1, 7)
(6, 4)
(6, 7)
(4, 7)

Example 4: Get all possible combinations of a list’s elements using recursion

Python3

import copy

def combinations(target, data):

    for i in range(len(data)):

        new_lis = copy.copy(target)
        new_data = copy.copy(data)
#         print(new_lis, new_data)
        new_lis.append(data[i])
        new_data = data[i+1:]

        print(new_lis)

        combinations(new_lis,
                     new_data)


target = []
data = [1, 2, 3, 4]

combinations(target, data)

Output:

(2, 3)
(2, 1)
(2, 6)
(2, 4)
(2, 7)
(3, 1)
(3, 6)
(3, 4)
(3, 7)
(1, 6)
(1, 4)
(1, 7)
(6, 4)
(6, 7)
(4, 7)