modify list element with list comprehension in python

Question

folks,

I want to modify list element with list comprehension. For example, if the element is negative, add 4 to it.

Thus the list

a = [1, -2 ,          


        

Answer 1

If you want to change the list in-place, this is almost the best way. List comprehension will create a new list. You could also use enumerate, and assignment must be done to a[i]:

for i, x in enumerate(a):
  if x < 0:
    a[i] = x + 4