Python – Elements with factors count less than K

Given a List of elements, get all elements with factors less than K.

Examples:

Input : test_list = [60, 12, 100, 17, 18, 19]. K = 4 
Output : [17, 19] 
Explanation : Both elements have 2 factors.

Input : test_list = [60, 12, 100, 360, 18, 900]. K = 4 
Output : [] 
Explanation : All have greater than 4 factors. 

Method #1: Using list comprehension

In this, we use list comprehension to get factors count, and other list comprehension to iterate for all the elements in list.

Python3

# Python3 code to demonstrate working of
# Elements with factors less than K
# Using list comprehension


def factors_less_k(ele, K):

    # comparing for factors
    return len([idx for idx in range(1, ele + 1) if ele % idx == 0]) <= K


# initializing list
test_list = [60, 12, 100, 17, 18]

# printing original list
print("The original list is : " + str(test_list))

# initializing K
K = 4

# checking for each element
res = [ele for ele in test_list if factors_less_k(ele, K)]

# printing result
print("Filtered elements : " + str(res))

Output

The original list is : [60, 12, 100, 17, 18]
Filtered elements : [17]

Method #2 : Using filter() + lambda + len() + list comprehension 

In this, task of filtering is done using filter() and lambda, len(), and list comprehension is used to perform tasks of getting factors.

Python3

# Python3 code to demonstrate working of
# Elements with factors less than K
# Using filter() + lambda + len() + list comprehension


def factors_less_k(ele, K):

    # comparing for factors
    return len([idx for idx in range(1, ele + 1) if ele % idx == 0]) <= K


# initializing list
test_list = [60, 12, 100, 17, 18]

# printing original list
print("The original list is : " + str(test_list))

# initializing K
K = 4

# filtering using filter() + lambda
res = list(filter(lambda ele: factors_less_k(ele, K), test_list))

# printing result
print("Filtered elements : " + str(res))

Output

The original list is : [60, 12, 100, 17, 18]
Filtered elements : [17]