MediumNLPnlp-355

Backoff Probability with Floor

Problem

Backoff uses the bigram maximum likelihood estimate when the bigram was seen, and scales the unigram probability by alpha otherwise: count / total when count > 0 else alpha * unigram_probability.

Given the bigram count and total, the unigram probability, and alpha, return the probability.

Hint

Only unseen bigrams fall back to the lower order.

Test cases

case 1

in: [5,100,0.01,0.4]

expected: 0.05

case 2

in: [0,100,0.01,0.4]

expected: 0.004

case 3

in: [1,4,0.5,0.1]

expected: 0.25

Starter codePython

def backoff_probability_with_floor(bigram_count, bigram_total, unigram_probability, alpha):
    # Your code here
    pass

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