python pandas DataFrame如何把两个DataFrame合并，pd.merge_ordered(), 替换df数据df.replace() ,df.apply()

python pandas DataFrame如何把两个DataFrame合并,pd.merge_ordered()

import pandas as pd
import numpy as np
df1 = pd.DataFrame({
    'datetime':['2021-01-01','2021-01-02','2021-01-03','2021-01-10'],
    'v1':[1,0,0,1],
    'v2':[0,0,0,0],
    'v3':['a','b','c','d']
})
df2 = pd.DataFrame({
    'datetime':['2021-01-01','2021-01-02','2021-01-11','2021-01-12'],
    'v1':[1,1,0,0],
    'v2':[1,0,1,0],
    'v3':['e','e','e','e']
})
print(df1)
print(df2)
 
df3 = pd.merge_ordered(df1,df2,on=['datetime'])#基于‘datetime’合并df1,df2
print(df3)
df3 = df3.replace(np.nan,0)#用0替换NAN
print(df3)
df3['v1'] = df3['v1_x'] + df3['v1_y'] 
df3['v2'] = df3['v2_x'] + df3['v2_y'] 
df3 = df3.replace(2,1)
df3['v3'] = df3.apply(lambda x: x['v3_y'] if x['v3_x'] == 0 else x['v3_x'],axis=1)#当df1['v3']没有值时，取df2['v3'],否则取df1['v3']
print(df3)

运行结果：