Lag-1 Difference Feature

Problem

Build the lag-1 difference feature: x_i - x_{i-1} for i >= 1.

Return [] when there are fewer than two values.

Hint

Each output element is the change from the previous step.

case 1

in: [[1,3,6,10]]

expected: [2,3,4]

case 2

in: [[5]]

expected: []

case 3

in: [[2,2,2]]

expected: [0,0]

case 4

in: [[]]

expected: []

Starter codePython

def difference_feature(values):
    # Your code here
    pass

4 test cases · run your code against them in the editor