HardNLPnlp-214

Formant Estimate (Lite)

Problem

Estimate formants by picking local maxima of the magnitude spectrum. Index i is a peak when spectrum[i] is greater than its left neighbor and at least its right neighbor.

Take the n highest peaks, breaking ties by frequency, and return their frequencies sorted ascending. Return an empty list when n is not positive or no peak exists.

Hint

Endpoints are never local maxima because they lack two neighbors.

Test cases

case 1

in: [[1,3,2,5,4],[100,200,300,400,500],2]

expected: [200,400]

case 2

in: [[1,2,3],[10,20,30],1]

expected: []

case 3

in: [[5,4,3,2],[10,20,30,40],2]

expected: []

case 4

in: [[1,5,1,5,1],[10,20,30,40,50],2]

expected: [20,40]

case 5

in: [[1,5,1],[10,20,30],0]

expected: []

Starter codePython

def formant_estimate_lite(spectrum, freqs, n):
    # Your code here
    pass

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