Average of a list of numbers, stored as strings in a Python list

Question

I want to calculate the average value of several lists in python. These lists contain numbers as strings. Empty string isn\'t zero, it means a missing value.

The be

Answer 1

num = ['1', '2', '', '6']
L = [int(n) for n in num if n]
ave = sum(L)/float(len(L)) if L else '-'

or

num = ['1', '2', '', '6']
L = [float(n) for n in num if n]
avg = sum(L)/len(L) if L else '-'