How to split a column into multiple columns with the index of the string with pandas?

Question

I have data frame, it looks like:

df = pd.DataFrame({"a":["sea001", "seac002"]})
print(df)

         a
0   sea001
1  seac002

I want to split the a column into two columns, the first three characters in column "b", the rest in column "c"

         a    b     c
0   sea001  sea   001
1  seac002  sea  c002

I want to use df.a.str.split(), but there is no option for me to separate the words after the index. How can I do this cleverly?

Answer 1

You can use str with slicing semantics to do this:

In [102]:
df['b'], df['c'] = df['a'].str[:3], df['a'].str[3:]
df

Out[102]:
         a    b     c
0   sea001  sea   001
1  seac002  sea  c002

Answer 2

try .str.extract() method:

In [104]: df[['b','c']] = df.a.str.extract(r'(.{3})(.*)', expand=True)

In [105]: df
Out[105]:
         a    b     c
0   sea001  sea   001
1  seac002  sea  c002