Finding the difference between consecutive numbers in a list (Python)

Question

Given a list of numbers, I am trying to write a code that finds the difference between consecutive elements. For instance, A = [1, 10, 100, 50, 40] so the outp

Answer 1

You can do:

[y-x for x, y in zip(A[:-1], A[1:])] 


>>> A = [1, 10, 100, 50, 40]
>>> [y-x for x, y in zip(A[:-1], A[1:])]
[9, 90, -50, -10]

Note that the difference will be negative if the right side is smaller, you can easily fix this (If you consider this wrong), I'll leave the solution for you.

Explanation:

The best explanation you can get is simply printing each part of the list comprehension.

• A[:-1] returns the list without the last element: [1, 10, 100, 50]
• A[1:] returns the list without the first element: [10, 100, 50, 40]
• zip(A[:-1], A[1:]) returns [(1, 10), (10, 100), (100, 50), (50, 40)]
• The last step is simply returning the difference in each tuple.