Python: One liner for summing up elements in a list meeting a condition

Question

How can I write this code python in one line?

num_positive_weights = 0
for i in  weights['value']:
    if i >= 0:
        num_positive_weights+=1

Answer 1

Well, that's not valid Python code (the i++ syntax isn't supported), but it would be as follows:

num_positive_weights = sum(i>=0 for i in weights['value'])

Answer 2

num_positive_weights = len([i for i in weights['value'] if i >= 0])