python列表推导式的三种形式

1、列表推导式可以较大幅度精简语句，但是也较容易发生错误。

def isHanzi(word):

    for hanzi in word:

        if (('\u4e00' <= hanzi) and (hanzi <= '\u9fff')):

            return True

    return False

#列表推导式1

X = [ '2019', 'is', '猪', '年']

Y = [ '2019', 'is', '猪', '年']

#[表达式 for 变量 in 列表]

X1 = [x for x in X]   #range(1,3)]

print(X1,type(X1))

输出 ['2019', 'is', '猪', '年'] <class 'list'>

2、def isHanzi(word):

    for hanzi in word:

        if (('\u4e00' <= hanzi) and (hanzi <= '\u9fff')):

            return True

    return False

#列表推导式1

X = [ '2019', 'is', '猪', '年']

Y = [ '2019', 'is', '猪', '年']

#列表推导式2

#[表达式 for 变量 in 列表 if 条件]

X2 = [x for x in X  if isHanzi(x)  ]

print(X2,type(X2))

输出 ['猪', '年'] <class 'list'>

3、def isHanzi(word):

    for hanzi in word:

        if (('\u4e00' <= hanzi) and (hanzi <= '\u9fff')):

            return True

    return False

#列表推导式1

X = [ '2019', 'is', '猪', '年']

Y = [ '2019', 'is', '猪', '年']

#[表达式1 if 条件 else 表达式2 for 变量 in 列表]

X3 = [x if isHanzi(x) else "" for x in Y]

print(X3,type(X3))

输出 ['', '', 输出 猪', '年'] <class 'list'>