Python |通过将每个元素填充 N 来增加列表大小
原文:https://www . geeksforgeeks . org/python-按填充增加列表大小-按 n 增加每个元素/
给定一个列表和一个整数 N，编写一个 Python 程序，通过将每个元素填充 N 来增加列表的大小
示例:
Input : lst = [1, 2, 3]
N = 3
Output : [1, 1, 1, 2, 2, 2, 3, 3, 3]
Input : lst = ['cats', 'dogs']
N = 2
Output : ['cats', 'cats', 'dogs', 'dogs']
方法#1 : 列表理解
# Python3 program to increase list size
# by padding each element by N
def increaseSize(lst, N):
return [el for el in lst for _ in range(N)]
# Driver code
lst = [1, 2, 3]
N = 3
print(increaseSize(lst, N))
Output:
[1, 1, 1, 2, 2, 2, 3, 3, 3]
使用functools.reduce()方法接近#2 :
reduce 函数将参数中传递的特定函数应用于所有列表元素。因此，在这种方法中，我们在每个元素上应用一个函数，它的出现乘以 n
# Python3 program to increase list size
# by padding each element by N
from functools import reduce
def increaseSize(lst, N):
return reduce(lambda x, y: x + y, [[el]*N for el in lst])
# Driver code
lst = [1, 2, 3]
N = 3
print(increaseSize(lst, N))
Output:
[1, 1, 1, 2, 2, 2, 3, 3, 3]
方法 3 : 使用 itertools.chain()
# Python3 program to increase list size
# by padding each element by N
from itertools import chain
def increaseSize(lst, N):
return list(chain(*([el]*N for el in lst)))
# Driver code
lst = [1, 2, 3]
N = 3
print(increaseSize(lst, N))
Output:
[1, 1, 1, 2, 2, 2, 3, 3, 3]
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