[py练习] 返回朋友名字的list

返回朋友名字的list

题目描述

Make a program that filters a list of strings and returns a list with only your friends name in it.

If a name has exactly 4 letters in it, you can be sure that it has to be a friend of yours! Otherwise, you can be sure he’s not…

Ex: Input = [“Ryan”, “Kieran”, “Jason”, “Yous”], Output = [“Ryan”, “Yous”]

Note: keep the original order of the names in the output.

我的实现

def friend(x):
    return [e for e in x if len(e) == 4 ]

print(["Ryan", "Kieran", "Jason","Yours"])

最佳实践1

def friend(x):
    return [f for f in x if len(f) == 4]

实现是一样的，使用列表解析实现的。

列表解析总结下

语法：

　　[expression for iter_val in iterable]

　　[expression for iter_val in iterable if cond_expr]