将两个DataFrame与一个列进行比较,并使用Panadas返回三个不同的输出

Question

我是Python和编码的初学者.我需要帮助比较两个不同长度和不同列标签的数据帧,除了一个.两个数据集之间相同的列是我想要比较数据帧的列.我的数据如下:

    df:  'fruits'  'trees'      'sports'    'countries'  

          bananas   mongolia     basketball    Spain
          grapes    Oak          rugby         Thailand
          oranges   Osage Orange baseball      Egypt
          apples    Maple        golf          Chile

    df2: 'cars'  'flowers'     'countries'    'vegetables'

          Audi    Rose          Spain           Carrots
          BMW     Tulip         Nigeria         Celery
          Honda   Dandelion     Egypt           Onion

我想根据列'countries'比较这两个数据帧,并在它们自己的数据帧中创建三个独立的输出.我一直在使用Pandas,并使用pd.concat将df1和df2合并为一个.我还想保留数据帧其余部分的行,即使它们不匹配.

这是我想要的输出:

输出#1:df中的值不在df2中:

    d3:  'fruits'  'trees'      'sports'    'countries'  

          grapes    Oak            rugby         Thailand
          apples    Maple          golf          Chile

输出#2:df2中的值不是df中的值

        df4: 'cars'  'flowers'   'countries'    'vegetables'

              BMW     Tulip       Nigeria         Celery

输出#3:df和df2中的值(组合了不同数据帧的列.)

df5: 'fruits'  'trees' 'sports'  'cars' 'flowers' 'countries' 'vegetables'  

  bananas   mongolia  basketball   Audi    Rose      Spain    Carrots 
Oranges  Osage Orange baseball    Honda   Dandelion  Egypt    Onion

希望这一切都有意义.我已经尝试了很多不同的东西(isin,DataFrame.diff和.difference,df-df2,numpy数组等)我已经看了一遍,我找不到我正在寻找的东西.任何帮助将不胜感激!谢谢!

Answer 1

设置参考

from StringIO import StringIO
import pandas as pd

txt1 = """fruits,trees,sports,countries
bananas,mongolia,basketball,Spain
grapes,Oak,rugby,Thailand
oranges,Osage,Orange baseball,Egypt
apples,Maple,golf,Chile"""

txt2 = """cars,flowers,countries,vegetables
Audi,Rose,Spain,Carrots
BMW,Tulip,Nigeria,Celery
Honda,Dandelion,Egypt,Onion"""

df = pd.read_csv(StringIO(txt1))

df2 = pd.read_csv(StringIO(txt2))

解决方案

def outer_parts(df1, df2):
    df3 = df1.merge(df2, indicator=True, how='outer')
    return {n: g.drop('_merge', 1) for n, g in df3.groupby('_merge')}


dfs = outer_parts(df, df2)

示范

dfs['both']

dfs['left_only']

dfs['right_only']