pandas read in csv column as float and set empty cells to 0

Question

Is it possible to read in a CSV as a pandas DataFrame and set spaces (or empty cells) to 0 in one line? Below is an illustration of the problem.

Input:

Answer 1

df.replace(r'\s+', 0, regex=True)

     a  b    c
0  0.0  a  0.0
1  0.0  b  1.0
2  1.5  c  2.5
3  2.1  d  3.0