From fabde384a33324dc9a9c55c1f4003196ec90564c Mon Sep 17 00:00:00 2001 From: Damien Lespiau Date: Sat, 27 Jun 2015 15:49:26 +0100 Subject: stats: Add support for the interquartile range (IQR) IQR is a good measure of dispersion. Signed-off-by: Damien Lespiau --- lib/igt_stats.c | 18 +++++++++++++++++- lib/igt_stats.h | 1 + lib/tests/igt_stats.c | 2 ++ 3 files changed, 20 insertions(+), 1 deletion(-) (limited to 'lib') diff --git a/lib/igt_stats.c b/lib/igt_stats.c index 66fd5636..caf3f374 100644 --- a/lib/igt_stats.c +++ b/lib/igt_stats.c @@ -216,7 +216,7 @@ uint64_t igt_stats_get_max(igt_stats_t *stats) * * The range can be a deceiving characterization of the values, because there * can be extreme minimal and maximum values that are just anomalies. Prefer - * the interquatile range or an histogram. + * the interquatile range (see igt_stats_get_iqr()) or an histogram. */ uint64_t igt_stats_get_range(igt_stats_t *stats) { @@ -339,6 +339,22 @@ void igt_stats_get_quartiles(igt_stats_t *stats, *q3 = ret; } +/** + * igt_stats_get_iqr: + * @stats: An #igt_stats_t instance + * + * Retrieves the + * [interquartile range](https://en.wikipedia.org/wiki/Interquartile_range) + * (IQR) of the @stats dataset. + */ +double igt_stats_get_iqr(igt_stats_t *stats) +{ + double q1, q3; + + igt_stats_get_quartiles(stats, &q1, NULL, &q3); + return (q3 - q1); +} + /** * igt_stats_get_median: * @stats: An #igt_stats_t instance diff --git a/lib/igt_stats.h b/lib/igt_stats.h index 887fa79c..6ee3ae69 100644 --- a/lib/igt_stats.h +++ b/lib/igt_stats.h @@ -59,6 +59,7 @@ uint64_t igt_stats_get_max(igt_stats_t *stats); uint64_t igt_stats_get_range(igt_stats_t *stats); void igt_stats_get_quartiles(igt_stats_t *stats, double *q1, double *q2, double *q3); +double igt_stats_get_iqr(igt_stats_t *stats); double igt_stats_get_mean(igt_stats_t *stats); double igt_stats_get_median(igt_stats_t *stats); double igt_stats_get_variance(igt_stats_t *stats); diff --git a/lib/tests/igt_stats.c b/lib/tests/igt_stats.c index c4c67760..c0649f33 100644 --- a/lib/tests/igt_stats.c +++ b/lib/tests/igt_stats.c @@ -102,6 +102,7 @@ static void test_quartiles(void) igt_assert_eq_double(q2, 40); igt_assert_eq_double(q3, 42.5); igt_assert_eq_double(igt_stats_get_median(&stats), 40); + igt_assert_eq_double(igt_stats_get_iqr(&stats), 42.5 - 25.5); igt_stats_fini(&stats); @@ -114,6 +115,7 @@ static void test_quartiles(void) igt_assert_eq_double(q2, 37.5); igt_assert_eq_double(q3, 40); igt_assert_eq_double(igt_stats_get_median(&stats), 37.5); + igt_assert_eq_double(igt_stats_get_iqr(&stats), 40 - 15); igt_stats_fini(&stats); } -- cgit v1.2.3