Concatenate two numerical values to make a new column using pandas?

问题

I have two columns in my dataframe.

var1    var2
01       001

I would like to create a third column that joins them together:

var1    var2    var3
01       001    01001

Does anyone know how to do this? Thank you!

回答1:

You can use simple concanecate by + with casting by astype:

df['var3'] = df.var1.astype(str) + df.var2.astype(str)
print df
  var1 var2   var3
0   01  001  01001

If type of both columns is string casting is omited:

print type(df.loc[0,'var1'])
<type 'str'>
print type(df.loc[0,'var2'])
<type 'str'>

df['var3'] = df.var1 + df.var2
print df
  var1 var2   var3
0   01  001  01001

回答2:

Convert to both columns to string and then join both the columns to form the third column.

Code:

df['var1']=df['var1'].astype(str)
df['var2']=df['var2'].astype(str)
df['var3'] = df[['var1', 'var2']].apply(lambda x: ''.join(x), axis=1)

来源：https://stackoverflow.com/questions/36774602/concatenate-two-numerical-values-to-make-a-new-column-using-pandas