Question

age = [19, 20, 21, 22, 23, 24, 25]
frequency = [2, 1, 1, 3, 2, 1, 1]
output_age = [19, 19, 20, 21, 22, 22, 22, 23, 23, 24, 25]

我们如何创建一个新列表，该列表会多次依赖另一个列表添加一个列表中的项目？

谢谢

Answer 1

使用列表理解：

output_age = [i for l in ([a]*f for a, f in zip(age, frequency)) for i in l]
#[19, 19, 20, 21, 22, 22, 22, 23, 23, 24, 25]

为什么？

我们首先将zip和age列表一起frequency一起使用，以便我们可以对它们进行一致的迭代。这样：

for a, f in zip(age, frequency):
    print(a, f)

给予：

然后，我们要重复a确定的每个元素f。这可以通过创建一个列表并将其相乘来完成。就像：

[4] * 3
#[4, 4, 4]

然后，我们需要解压缩这些值，以便将这个表达式包装在生成器中（用方括号表示）并对其进行迭代。这使列表变平。请注意，有alternative ways可以实现这一目标（例如使用itertools.chain.from_iterable）。

另一种方法是通过迭代a对象来重复数字range，而不是将列表相乘以获得重复。

此方法类似于：

output_age = [a for a, f in zip(age, frequency) for _ in range(f)]
#[19, 19, 20, 21, 22, 22, 22, 23, 23, 24, 25]

Answer 2

使用itertools和zip

例如：

from itertools import chain
age = [19, 20, 21, 22, 23, 24, 25]
frequency = [2, 1, 1, 3, 2, 1, 1]

print( list(chain.from_iterable([[i] * v for i,v in zip(age, frequency)])) )

输出：

[19, 19, 20, 21, 22, 22, 22, 23, 23, 24, 25]

注意： chain.from_iterable将列表变平。

Answer 3

这是使用zip和range的解决方案

>>> age = [19, 20, 21, 22, 23, 24, 25]
>>> frequency = [2, 1, 1, 3, 2, 1, 1]
>>> [a for a,f in zip(age, frequency) for _ in range(f)]
[19, 19, 20, 21, 22, 22, 22, 23, 23, 24, 25]

Answer 4

最简单易懂的方式

age = [19, 20, 21, 22, 23, 24, 25]
frequency = [2, 1, 1, 3, 2, 1, 1]

output_age = []
for age, freq in zip(age, frequency):
    for _ in range(freq):
        output_age.append(age)

Answer 5

您也可以使用sum函数来执行此操作，尽管对于生产代码不建议这样做：

age = [19, 20, 21, 22, 23, 24, 25]
frequency = [2, 1, 1, 3, 2, 1, 1]
output_age = sum([[age[i]] * frequency[i] for i in range(len(age))],[])
print(output_age)

输出：

[19, 19, 20, 21, 22, 22, 22, 23, 23, 24, 25]

Answer 6

您需要：

import functools
output_age = functools.reduce(lambda x, y:x+y, [[age[i]] * frequency[i] for i in range(len(age))])

Answer 7

age = [19, 20, 21, 22, 23, 24, 25]
frequency = [2, 1, 1, 3, 2, 1, 1]
new_list = zip(age, frequency)
output_age=[]
for x,y in new_list:
  for i in range(y):
    output_age.append(x)

输出：

[19，19，20，21，22，22，22，23，23，24，25]

在Python中使用频率列表创建列表

7 个答案: