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

Question

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

Solution

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

Comments

[Jeril]

when I used this I am getting the following warning SettingWithCopyWarning: A value is trying to be set on a copy of a slice from a DataFrame. Try using .loc[row_indexer,col_indexer] = value instead is there an another way

[jezrael]

@Jeril - Obviously problem is in another code, check this