DataFrame join用法
#！ /user/bin/env python
#_*_coding:utf-8 -*_
#__author__ = '株洲市易美智能工程有限责任公司'
#Email:[email protected]
import pandas as pd
import numpy as np
df1 = pd.DataFrame(np.ones(12).reshape(3,4),columns = list('abcd'),index = list('ABC'))
df2 = pd.DataFrame(np.zeros((3,5)),columns = list('efghi'),index = list('ABC'))
df3 = pd.DataFrame(np.zeros((5,2)),columns = list('jk'),index = list('AEBGH'))
print(df2.join(df1))#两个都有相同的行的效果
print(df1.join(df3)) #df3 和df1都有A,B行就可以join在一起，df3没有C行所以join后的C行就是'NaN'
Results output:
efghiabcd
A 0.0 0.0 0.0 0.0 0.0 1.0 1.0 1.0 1.0
B 0.0 0.0 0.0 0.0 0.0 1.0 1.0 1.0 1.0
C 0.0 0.0 0.0 0.0 0.0 1.0 1.0 1.0 1.0
abcdjk
A 1.0 1.0 1.0 1.0 0.0 0.0
B 1.0 1.0 1.0 1.0 0.0 0.0
C 1.0 1.0 1.0 1.0 NaN NaN
