select the first N elements of each row in a column

Question

I am looking to select the first two elements of each row in column a and column b.

Here is an example

df = pd.DataFrame({'a': ['A123', 'A567','A100'], 'b': ['A156', 'A266666','A35555']})

>>> df
      a        b
0  A123     A156
1  A567  A266666
2  A100   A35555

desired output

>>> df
      a      b
0     A1     A1
1     A5     A2
2     A1     A3

I have been trying to use df.loc but not been successful.

Answer 1

Use

In [905]: df.apply(lambda x: x.str[:2])
Out[905]:
    a   b
0  A1  A1
1  A5  A2
2  A1  A3

Or,

In [908]: df.applymap(lambda x: x[:2])
Out[908]:
    a   b
0  A1  A1
1  A5  A2
2  A1  A3

Answer 2

In [107]: df.apply(lambda c: c.str.slice(stop=2))
Out[107]:
    a   b
0  A1  A1
1  A5  A2
2  A1  A3