python pandas : compare two columns for equality and result in third dataframe

问题

how to print the result in the separate dataframe after comparing it with two columns in different dataframes.

consider two dataframes:

df1 = pd.DataFrame({'col1':['audi','cars']})  
df2 = pd.DataFrame({'col2':['audi','bike']})

print (df1)

    col1
0  audi
1  cars 

print (df2)

     col2
0   audi
1   bike

now the result should be in a different dataframe.

      col1  col2  result
0     audi  audi   no change
1     cars  bike   changed

回答1:

Use concat with numpy.where:

df = pd.concat([df1, df2], axis=1)
df['result'] = np.where(df['col1'] == df['col2'], 'no change', 'changed')
print (df)
   col1  col2     result
0  audi  audi  no change
1  cars  bike    changed

来源：https://stackoverflow.com/questions/52777668/python-pandas-compare-two-columns-for-equality-and-result-in-third-dataframe