Python | Size Range Combinations in list
The problem of finding the combinations of list elements of specific size has been discussed. But sometimes, we require more and we wish to have all the combinations of elements of all sizes in range between i and j. Let’s discuss certain ways in which this function can be performed.
Method #1 : Using list comprehension + combinations() This task can be performed using the list comprehension which can perform the task of varying the combination length and combination() can perform the actual task of finding combinations.
# Python3 code to demonstrate working of
# Size Range Combinations in list
# Using list comprehension + combinations()
from itertools import combinations
# initializing list
test_list = [4, 5, 6, 7, 3, 8]
# printing original list
print("The original list is : " + str(test_list))
# initializing i, j
i, j = 2, 4
# Size Range Combinations in list
# Using list comprehension + combinations()
res1 = [com for sub in range(j) for com in combinations(test_list, sub + 1)]
res2 = [com for sub in range(i - 1) for com in combinations(test_list, sub + 1)]
res = list(set(res1) - set(res2))
# Printing result
print("The combinations of elements in range of i and j : " + str(res))
# Python3 code to demonstrate working of# Size Range Combinations in list# Using list comprehension + combinations()from itertools import combinations# initializing listtest_list = [4, 5, 6, 7, 3, 8]# printing original listprint("The original list is : " + str(test_list))# initializing i, j i, j = 2, 4# Size Range Combinations in list# Using list comprehension + combinations()res1 = [com for sub in range(j) for com in combinations(test_list, sub + 1)]res2 = [com for sub in range(i - 1) for com in combinations(test_list, sub + 1)]res = list(set(res1) - set(res2))# Printing resultprint("The combinations of elements in range of i and j : " + str(res))The original list is : [4, 5, 6, 7, 3, 8] The combinations of elements in range of i and j : [(7, 3), (4, 7), (4, 5, 6, 3), (4, 8), (5, 6), (5, 6, 3), (4, 6, 8), (5, 7, 8), (5, 6, 7, 8), (6, 7, 3), (6, 7, 3, 8), (5, 8), (5, 3, 8), (5, 6, 7), (6, 7), (4, 7, 3, 8), (5, 6, 3, 8), (5, 6, 8), (4, 6, 7, 8), (6, 3), (6, 3, 8), (5, 7, 3, 8), (7, 3, 8), (5, 7, 3), (4, 5, 7, 3), (4, 7, 8), (4, 6, 7), (4, 5, 3), (4, 5), (4, 6, 7, 3), (6, 7, 8), (4, 6, 3, 8), (4, 5, 6, 8), (4, 3, 8), (4, 5, 7, 8), (4, 5, 6), (5, 3), (4, 6, 3), (4, 5, 6, 7), (4, 5, 7), (4, 6), (6, 8), (4, 5, 3, 8), (4, 5, 8), (5, 7), (3, 8), (4, 3), (5, 6, 7, 3), (4, 7, 3), (7, 8)]
Time Complexity: O(n!), where n is the number of elements in the list “test_list”.
Auxiliary Space: O(n), where n is the number of elements in the list “test_list”.
Method 2 : Using loop + extend() + combinations() This method is similar to above method, just the loop is being using to iterate for combination size and extend() performs the task of adding the combinations one after another to final result.
# Python3 code to demonstrate working of
# Size Range Combinations in list
# Using loop + extend() + combinations()
from itertools import combinations
# initializing list
test_list = [4, 5, 6, 7, 3, 8]
# printing original list
print("The original list is : " + str(test_list))
# initializing i, j
i, j = 2, 4
# Size Range Combinations in list
# Using loop + extend() + combinations()
res = []
for sub in range(j):
if sub >= (i - 1):
res.extend(combinations(test_list, sub + 1))
# Printing result
print("The combinations of elements in range of i and j : " + str(res))
# Python3 code to demonstrate working of# Size Range Combinations in list# Using loop + extend() + combinations()from itertools import combinations# initializing listtest_list = [4, 5, 6, 7, 3, 8]# printing original listprint("The original list is : " + str(test_list))# initializing i, j i, j = 2, 4# Size Range Combinations in list# Using loop + extend() + combinations()res = []for sub in range(j): if sub >= (i - 1): res.extend(combinations(test_list, sub + 1))# Printing resultprint("The combinations of elements in range of i and j : " + str(res))The original list is : [4, 5, 6, 7, 3, 8] The combinations of elements in range of i and j : [(7, 3), (4, 7), (4, 5, 6, 3), (4, 8), (5, 6), (5, 6, 3), (4, 6, 8), (5, 7, 8), (5, 6, 7, 8), (6, 7, 3), (6, 7, 3, 8), (5, 8), (5, 3, 8), (5, 6, 7), (6, 7), (4, 7, 3, 8), (5, 6, 3, 8), (5, 6, 8), (4, 6, 7, 8), (6, 3), (6, 3, 8), (5, 7, 3, 8), (7, 3, 8), (5, 7, 3), (4, 5, 7, 3), (4, 7, 8), (4, 6, 7), (4, 5, 3), (4, 5), (4, 6, 7, 3), (6, 7, 8), (4, 6, 3, 8), (4, 5, 6, 8), (4, 3, 8), (4, 5, 7, 8), (4, 5, 6), (5, 3), (4, 6, 3), (4, 5, 6, 7), (4, 5, 7), (4, 6), (6, 8), (4, 5, 3, 8), (4, 5, 8), (5, 7), (3, 8), (4, 3), (5, 6, 7, 3), (4, 7, 3), (7, 8)]
