How can I determine that the value of column1 in df1 contains in column1 in df2 starting strictly fr-CodePudding

I have 2 dataframes:

df1=pd.DataFrame({'number': ['14578', '45621', '1564']})
df2=pd.DataFrame({'number': ['1457891521', '123456215', '15643']})

My question how is it possible to determine if df1['number'] contains in df2['number'] strictly from the left.

Desirable result:

number  full number
0   14578   1457891521
1   45621   0
2   1564    15643

CodePudding user response：

You unfortunately need to loop here:

df1['full number'] = [b if b.startswith(a) else ''
                      for a,b in zip(df1['number'], df2['number'])]

Output:

  number full number
0  14578  1457891521
1  45621            
2   1564       15643

CodePudding user response：

Another possible solution, using numpy, specifically numpy.char.startswith:

x2, x1 = df2['number'].values.astype(str), df1['number'].values.astype(str)
out = df1
out['full number'] = df2.loc[np.char.startswith(x2, x1), 'number']

Output:

  number full number
0  14578  1457891521
1  45621         NaN
2   1564       15643