welch_ttest.py

#!/usr/bin/env python
# /// script
# requires-python = ">=3.10"
# dependencies = [
#     "scipy",
# ]
# ///

"""This script performs Welch's t-test on a JSON export file with two
benchmark results to test whether or not the two distributions are
the same."""

import argparse
import json
import sys

from scipy import stats

parser = argparse.ArgumentParser(description=__doc__)
parser.add_argument("file", help="JSON file with two benchmark results")
args = parser.parse_args()

with open(args.file) as f:
    results = json.load(f)["results"]

if len(results) != 2:
    print("The input file has to contain exactly two benchmarks")
    sys.exit(1)

a, b = (x["command"] for x in results[:2])
X, Y = (x["times"] for x in results[:2])

print(f"Command 1: {a}")
print(f"Command 2: {b}\n")

t, p = stats.ttest_ind(X, Y, equal_var=False)
th = 0.05
dispose = p < th
print(f"t = {t:.3}, p = {p:.3}")
print()

if dispose:
    print(f"There is a difference between the two benchmarks (p < {th}).")
else:
    print(f"The two benchmarks are almost the same (p >= {th}).")