Series.map

Series.map(arg, na_action=None)
根据输入对应关系映射系列的值。
用于将Series中的每个值替换为另一个值，该值可能来自函数、dict或Series。

Parameters

Example

import pandas as pd
df = pd.DataFrame({'site':['google', 'baidu', 'wiki', 'pandas'],
                     'color': ['red', 'black', None, 'red']})
df.site = df.site.map({'google': 'facebook', 'baidu': 'bing'})
df
--------------------------------------------------------------------
    site        color
0    facebook    red
1    bing        black
2    NaN            None
3    NaN            red

Example

import pandas as pd
df = pd.DataFrame({'site':['google', 'baidu', 'wiki', 'pandas'],
                     'color': ['red', 'black', None, 'red']})
df.site = df.site.map('I like {}'.format)
df
------------------------------------------------------
    site            color
0    I like google    red
1    I like baidu    black
2    I like wiki        None
3    I like pandas    red

Example

import pandas as pd
df = pd.DataFrame({'site':['google', 'baidu', 'wiki', 'pandas'],
                     'color': ['red', 'black', None, 'red']})
df.color = df.color.map('I like {}'.format, na_action='ignore')
df
    site    color
0    google    I like red
1    baidu    I like black
2    wiki    None
3    pandas    I like red

Example

import pandas as pd
df = pd.DataFrame({'site':['google', 'baidu', 'wiki', 'pandas'],
                     'color': ['red', 'black', None, 'red']})
df.color = df.color.map(lambda x: "blue" if x is None else x)
df
    site    color
0    google    red
1    baidu    black
2    wiki    blue
3    pandas    red