熊猫有条件地将数据帧添加到另一个数据帧

Question

from pandas import DataFrame

import pandas as pd

df_1 = pd.DataFrame(

    {

        'Horses':["Horse1","Horse2","Horse3"],

        'Age':[2,5,3],

        'Price':["$100,000","$80,000","$60,000"],

        'Weight':["180g","140kg","240kg"]})  

df_2 = pd.DataFrame(

    {

        'Horses':["Horse4","Horse1","Horse5"],

        'Age':[4,3,2],

        'Price':["$75,000","$35,000","$120,000"],

        'Weight':["210kg","110kg","197kg"]})  

df_final = pd.DataFrame(

    {

        'Horses':["Horse1","Horse2","Horse3","Horse4","Horse5"],

        'Age':[2,5,3,4,2],

        'Price':["$100,000","$80,000","$60,000","$75,000","$120,000"],

        'Weight':["180g","140kg","240kg","210kg","197kg"]})

如何从前两个数据帧 bf_1 和 bf_2 创建 df_final DataFrame ？

我该如何编码这个条件：如果输入“Horse1”，它会像上面一样被擦除，否则它会被添加到底部

Answer 1

使用 combine_firstdf_1.set_index('Horses',inplace=True)df_1=df_1.combine_first(df_2.set_index('Horses')).reset_index()df_1   Horses  Age     Price Weight0  Horse1  2.0  $100,000   180g1  Horse2  5.0   $80,000  140kg2  Horse3  3.0   $60,000  240kg3  Horse4  4.0   $75,000  210kg4  Horse5  2.0  $120,000  197kg