Python – Get Indices of Even Elements from list

Sometimes, while working with Python lists, we can have a problem in which we wish to find Even elements. This task can occur in many domains such as web development and while working with Databases. We might sometimes, require to just find the indices of them. Let’s discuss certain way to find indices of Even elements.

Method #1 : Using loop
This is brute force method in which this task can be performed. In this, we check for even element in list and append its index accordingly.

# Python3 code to demonstrate working of
# Even Elements indices
# using loop

# initialize list
test_list = [5, 6, 10, 4, 7, 1, 19]

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

# Even Elements indices
# using loop
res = []
for idx, ele in enumerate(test_list):
    if ele % 2 == 0:
        res.append(idx)

# printing result
print("Indices list Even elements is : " + str(res))

Output :

The original list is : [5, 6, 10, 4, 7, 1, 19]
Indices list Even elements is : [1, 2, 3]

Method #2 : Using list comprehension
This is the shorthand by which this task can be performed. This method works in similar way as the above method. The difference is that it’s a one liner.

# Python3 code to demonstrate working of
# Even Elements indices
# using list comprehension

# initialize list
test_list = [5, 6, 10, 4, 7, 1, 19]

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

# Even Elements indices
# using list comprehension
res = [idx for idx, ele in enumerate(test_list) if ele % 2 == 0]

# printing result
print("Indices list Even elements is : " + str(res))

Output :

The original list is : [5, 6, 10, 4, 7, 1, 19]
Indices list Even elements is : [1, 2, 3]