Question

Given a list, I would like to apply some set of operations to a subset(slice) of the list, and store the result of each transformation in the original list.

My background is in Ada, which led me to make the following mistake:

Number_List = [0,1,2,3,4,5,6,7,8,9]
for Index, Number in enumerate(Number_List[1:]):
  Number_List[Index] = Number + 1

Giving a new Number_List of: 2,3,4,5,6,7,8,9,10,9 and teaching me that a slice of an array is re-indexed to 0.

I’ve moved to the following, which is cumbersome but functional.

Number_List = [0,1,2,3,4,5,6,7,8,9]
for Index in range(1,len(Number_List))
  Number_List[Index] = Number_List[Index]+1

I am looking for a more elegant way to do this.

Answer 1

enumerate takes a start parameter:

Number_List = [0,1,2,3,4,5,6,7,8,9]
for Index, Number in enumerate(Number_List[1:], start=1):
  Number_List[Index] = Number + 1

You can also write

Number_List[1:] = [x+1 for x in Number_List[1:]]