深度学习（三）pandas replace and map

import numpy as np
import pandas as pd
from pandas import DataFrame as dframe
from pandas import Series

df1 = dframe({"city":['BJ','SH','GZ'],"Population":[100,200,300]})

 	city 	Population
0 	BJ 	100
1 	SH 	200
2 	GZ 	300

df1['GDP']=Series([1000,2000,1100]) #df1增加一列，只能贼值index是0，1，2的
df1

	city 	Population 	GDP
0 	BJ 	100 	1000
1 	SH 	200 	2000
2 	GZ 	300 	1100

gdp_map={'BJ':1000,'SH':2000,'GZ':1500}
df1['GDP']=df1['city'].map(gdp_map)  #不需要关心index
 	city 	Population 	GDP
0 	BJ 	100 	1000
1 	SH 	200 	2000
2 	GZ 	300 	1500

s1 = Series(np.arange(10))

s1.replace([1,2,3],[10,20,30])
0     0
1    10
2    20
3    30
4     4
5     5
6     6
7     7
8     8
9     9
dtype: int64
s1.replace({1:30})
0     0
1    30
2     2
3     3
4     4
5     5
6     6
7     7
8     8
9     9
dtype: int64