Python – 在嵌套混合元组中提取偶数元素

有时，在使用Python元组时，我们可能会遇到需要从元组中获取所有偶数元素的问题。元组可以嵌套或混合。这种问题可能发生在数据域中。让我们讨论可以执行此任务的某些方式。

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))), ) 
 

方法 #1：使用递归 + isinstance() + 循环
这是可以执行此任务的方式之一。在此，我们使用 isinstance() 执行使元素实例为整数的任务，一旦遇到元组，该函数就会递归。

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))

输出 ：

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

方法 #2：使用递归 + isinstance() + 生成器表达式
此方法以与上述方法类似的方式执行此任务。不同之处在于它是上述方法的简写，使用生成器表达式在一行中完成工作。

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))

输出 ：

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