Pandas: change data type of Series to String

Question

I use Pandas 'ver 0.12.0' with Python 2.7 and have a dataframe as below:

df = pd.DataFrame({'id' : [123,512,'zhub1', 12354.3, 129, 753, 295, 610],                     'colour': ['black', 'white','white','white',                             'black', 'black', 'white', 'white'],                     'shape': ['round', 'triangular', 'triangular','triangular','square',                                         'triangular','round','triangular']                     },  columns= ['id','colour', 'shape']) 

The id Series consists of some integers and strings. Its dtype by default is object. I want to convert all contents of id to strings. I tried astype(str), which produces the output below.

df['id'].astype(str) 0    1 1    5 2    z 3    1 4    1 5    7 6    2 7    6 

1) How can I convert all elements of id to String?

2) I will eventually use id for indexing for dataframes. Would having String indices in a dataframe slow things down, compared to having an integer index?

Answer 1

You can convert all elements of id to str using apply

df.id.apply(str)  0        123 1        512 2      zhub1 3    12354.3 4        129 5        753 6        295 7        610 

Edit by OP:

I think the issue was related to the Python version (2.7.), this worked:

df['id'].astype(basestring) 0        123 1        512 2      zhub1 3    12354.3 4        129 5        753 6        295 7        610 Name: id, dtype: object