How to one-hot-encode sentences at the character level?

Question

I would like to convert a sentence to an array of one-hot vector. These vector would be the one-hot representation of the alphabet. It would look like the following:

Answer 1

With pandas, you can use pd.get_dummies by passing a categorical Series:

import pandas as pd
import string
low = string.ascii_lowercase

pd.get_dummies(pd.Series(list(s)).astype('category', categories=list(low)))
Out: 
   a  b  c  d  e  f  g  h  i  j ...  q  r  s  t  u  v  w  x  y  z
0  0  0  0  0  0  0  0  1  0  0 ...  0  0  0  0  0  0  0  0  0  0
1  0  0  0  0  1  0  0  0  0  0 ...  0  0  0  0  0  0  0  0  0  0
2  0  0  0  0  0  0  0  0  0  0 ...  0  0  0  0  0  0  0  0  0  0
3  0  0  0  0  0  0  0  0  0  0 ...  0  0  0  0  0  0  0  0  0  0
4  0  0  0  0  0  0  0  0  0  0 ...  0  0  0  0  0  0  0  0  0  0

[5 rows x 26 columns]