为什么df.index.map(dict)不像df ['column_name']。map(dict)?使用字典映射数据帧索引
这里是试图用index.map一个小例子:
import pandas as pd
df = pd.DataFrame({'one': {'A': 10, 'B': 20, 'C': 30, 'D': 40, 'E': 50}})
map_dict = {'A': 'every', 'B': 'good', 'C': 'boy', 'D': 'does', 'E': 'fine'}
df
'''
one
A 10
B 20
C 30
D 40
E 50
'''
df['two'] = df.index.map(mapper=map_dict)
这就提出了TypeError: 'dict' object is not callable
喂养它拉姆达作品:
df['two'] = df.index.map(mapper=(lambda x: map_dict[x])); df
'''
one two
A 10 every
B 20 good
C 30 boy
D 40 does
E 50 fine
'''
然而,重置索引和映射在列上按预期工作,无需投诉:
df.reset_index(inplace=True)
df.rename(columns={'index': 'old_ndx'}, inplace=True) #so there's no index name confusion
df['two'] = df.old_ndx.map(map_dict); df
'''
old_ndx one two
0 A 10 every
1 B 20 good
2 C 30 boy
3 D 40 does
4 E 50 fine
'''
添加
get
根据[该文档](HTTP://pandas.pydata .org/pandas-docs/version/0.18.1/generated/pandas.Index.map.html),'pandas.Index.map'需要可调用。你的问题*为什么*是做出这个设计决定的? –[这里](https://github.com/pandas-dev/pandas/issues/12756)是一个相关的问题。它似乎只是在裂缝中滑过,他们没有得到修理。它似乎是[目前正在补救](https://github.com/pandas-dev/pandas/pull/15081)。 –