Python|交替合并两个列表

给定两个列表，编写一个Python程序以另一种方式合并给定的列表，前提是这两个列表的长度相等。

例子：

Input : lst1 = [1, 2, 3]
        lst2 = ['a', 'b', 'c']
Output : [1, 'a', 2, 'b', 3, 'c']

Input : lst1 = ['name', 'alice', 'bob']
        lst2 = ['marks', 87, 56]
Output : ['name', 'marks', 'alice', 87, 'bob', 56]

方法#1：列表理解

# Python3 program to merge two lists 
# alternatively
  
def countList(lst1, lst2):
    return [sub[item] for item in range(len(lst2))
                      for sub in [lst1, lst2]]
      
# Driver code
lst1 = [1, 2, 3]
lst2 = ['a', 'b', 'c']
print(countList(lst1, lst2))

输出：

[1, 'a', 2, 'b', 3, 'c']

有一种替代方法可以将列表推导与zip()一起使用，如下所示 -

def countList(lst1, lst2):
    return [item for pair in zip(lst1, lst2 + [0])
                                 for item in pair]

方法#2：使用itertools.cycle()

# Python3 program to merge two lists 
# alternatively
from itertools import cycle
  
def countList(lst1, lst2):
    iters = [iter(lst1), iter(lst2)]
    return list(iter.__next__() for iter in cycle(iters))
      
# Driver code
lst1 = [1, 2, 3]
lst2 = ['a', 'b', 'c']
print(countList(lst1, lst2))

输出：

[1, 'a', 2, 'b', 3, 'c']

方法 #3：使用reduce()

# Python3 program to merge two lists 
# alternatively
import operator
from functools import reduce
  
def countList(lst1, lst2):
    return reduce(operator.add, zip(lst1, lst2))
      
# Driver code
lst1 = [1, 2, 3]
lst2 = ['a', 'b', 'c']
print(countList(lst1, lst2))

输出：

(1, 'a', 2, 'b', 3, 'c')

方法 #4：使用numpy模块

# Python3 program to merge two lists 
# alternatively
import numpy as np
  
def countList(lst1, lst2):
    return np.array([[i, j] for i, j in zip(lst1, lst2)]).ravel()
      
# Driver code
lst1 = [1, 2, 3]
lst2 = ['a', 'b', 'c']
print(countList(lst1, lst2))

输出：

['1' 'a' '2' 'b' '3' 'c']