Recurrence Rate

Problem

Compute the recurrence rate: the fraction of unordered pairs (i, j) with abs(x[i] - x[j]) <= threshold.

Return 0.0 for a series with fewer than two points. Pairs are counted once.

Hint

This is the simplest point of a recurrence plot: its overall density.

case 1

in: [[1,2,3,4],1]

expected: 0.5

case 2

in: [[1,1,1],0]

expected: 1

case 3

in: [[0,10],5]

expected: 0

case 4

in: [[1,2],1]

expected: 1

Starter codePython

def recurrence_rate(series, threshold):
    # Your code here
    pass

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