Invert negative values in a list

Question

I am trying to convert a list that contains negative values, to a list of non-negative values; inverting the negative ones. I have tried abs but it didn\'t work

Answer 1

Your attempt didn't work because abs() takes an integer, not a list. To do this, you'll have to either loop through the list:

x = [10,9,8,7,6,5,4,3,2,1,0,-1,-2,-3,-4,-5,-6,-7,-8,-9,-10]
for i in range(len(x)):
     x[i] = abs(x[i])

Or you can use list comprehension, which is shorter:

x = [abs(i) for i in x]

Or simply use the built-in map function, which is even shorter :)

x = list(map(abs, x))

Hope this helps!