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

Try this:

 b = [x + 4 if x < 0 else x for x in a]

Or if you like map more than a list comprehension:

 b = map(lambda x: x + 4 if x < 0 else x, a)