python: getting around division by zero

Question

I have a big data set of floating point numbers. I iterate through them and evaluate np.log(x) for each of them. I get

RuntimeWarning: divide b         


        

Answer 1

use exception handling:

In [27]: def safe_ln(x):
    try:
        return math.log(x)
    except ValueError:       # np.log(x) might raise some other error though
        return float("-inf")
   ....:     

In [28]: safe_ln(0)
Out[28]: -inf

In [29]: safe_ln(1)
Out[29]: 0.0

In [30]: safe_ln(-100)
Out[30]: -inf