Python – Extract Even elements in Nested Mixed Tuple

Sometimes, while working with Python tuples, we can have a problem in which we need to get all the even elements from the tuple. The tuples can be nested or mixed. This kind of problem can occur in data domains. Let’s discuss certain ways in which this task can be performed.

Input : test_tuple = (5, (7, 6, (2, (4, )))) 
Output : ((6, (2, (4, ))), )

Input : test_tuple = (5, (8, 6, (2, (4, 8)))) 
Output : ((8, 6, (2, (4, 8))), ) 

Method #1 : Using recursion + isinstance() + loop
This is one of the ways in which this task can be performed. In this, we perform the task of getting the element instance to be integer using isinstance(), and the function is recursed once tuple is encountered.

Python3

# Python3 code to demonstrate working of
# Extract Even elements in Nested Mixed Tuple
# Using recursion + isinstance() + loop

# helper_fnc
def even_ele(test_tuple, even_fnc):
    res = tuple()
    for ele in test_tuple:
        if isinstance(ele, tuple):
            res += (even_ele(ele, even_fnc), )
        elif even_fnc(ele):
            res += (ele, )
    return res

# initializing tuples
test_tuple = (4, 5, (7, 6, (2, 4)), 6, 8)

# printing original tuple
print("The original tuple : " + str(test_tuple))

# Extract Even elements in Nested Mixed Tuple
# Using recursion + isinstance() + loop
res = even_ele(test_tuple, lambda x: x % 2 == 0)

# printing result
print("Even elements of tuple : " + str(res))

Output : 

The original tuple : (4, 5, (7, 6, (2, 4)), 6, 8)
Even elements of tuple : (4, (6, (2, 4)), 6, 8)

Method #2 : Using recursion + isinstance() + generator expression
This method performs this task in a similar manner as the above method. The difference is just that it is shorthand to the above method, does the job in one line using generator expression.

Python3

# Python3 code to demonstrate working of
# Extract Even elements in Nested Mixed Tuple
# Using recursion + isinstance() + generator expression

# helper_fnc
def even_ele(test_tuple, even_fnc):
    return tuple(even_ele(ele, even_fnc) if isinstance(ele, tuple) else ele
    for ele in test_tuple if isinstance(ele, tuple) or even_fnc(ele))

# initializing tuples
test_tuple = (4, 5, (7, 6, (2, 4)), 6, 8)

# printing original tuple
print("The original tuple : " + str(test_tuple))

# Extract Even elements in Nested Mixed Tuple
# Using recursion + isinstance() + generator expression
res = even_ele(test_tuple, lambda x: x % 2 == 0)

# printing result
print("Even elements of tuple : " + str(res))

Output : 

The original tuple : (4, 5, (7, 6, (2, 4)), 6, 8)
Even elements of tuple : (4, (6, (2, 4)), 6, 8)