rust-average/tests/mean.rs

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#![cfg_attr(feature = "cargo-clippy", allow(float_cmp, map_clone))]
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use core::iter::Iterator;
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use average::{MeanWithError, Estimate, Merge, assert_almost_eq};
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#[test]
fn trivial() {
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let mut a = MeanWithError::new();
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assert_eq!(a.len(), 0);
a.add(1.0);
assert_eq!(a.mean(), 1.0);
assert_eq!(a.len(), 1);
assert_eq!(a.sample_variance(), 0.0);
assert_eq!(a.population_variance(), 0.0);
assert_eq!(a.error(), 0.0);
a.add(1.0);
assert_eq!(a.mean(), 1.0);
assert_eq!(a.len(), 2);
assert_eq!(a.sample_variance(), 0.0);
assert_eq!(a.population_variance(), 0.0);
assert_eq!(a.error(), 0.0);
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}
#[test]
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fn simple() {
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let a: MeanWithError = (1..6).map(f64::from).collect();
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assert_eq!(a.mean(), 3.0);
assert_eq!(a.len(), 5);
assert_eq!(a.sample_variance(), 2.5);
assert_almost_eq!(a.error(), f64::sqrt(0.5), 1e-16);
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}
#[cfg(feature = "serde1")]
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#[test]
fn simple_serde() {
let a: MeanWithError = (1..6).map(f64::from).collect();
let b = serde_json::to_string(&a).unwrap();
assert_eq!(&b, "{\"avg\":{\"avg\":3.0,\"n\":5},\"sum_2\":10.0}");
let c: MeanWithError = serde_json::from_str(&b).unwrap();
assert_eq!(c.mean(), 3.0);
assert_eq!(c.len(), 5);
assert_eq!(c.sample_variance(), 2.5);
assert_almost_eq!(c.error(), f64::sqrt(0.5), 1e-16);
}
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#[test]
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fn numerically_unstable() {
// The naive algorithm fails for this example due to cancelation.
let big = 1e9;
let sample = &[big + 4., big + 7., big + 13., big + 16.];
let a: MeanWithError = sample.iter().collect();
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assert_eq!(a.sample_variance(), 30.);
}
#[test]
fn merge() {
let sequence: &[f64] = &[1., 2., 3., 4., 5., 6., 7., 8., 9.];
for mid in 0..sequence.len() {
let (left, right) = sequence.split_at(mid);
let avg_total: MeanWithError = sequence.iter().collect();
let mut avg_left: MeanWithError = left.iter().collect();
let avg_right: MeanWithError = right.iter().collect();
avg_left.merge(&avg_right);
assert_eq!(avg_total.len(), avg_left.len());
assert_eq!(avg_total.mean(), avg_left.mean());
assert_eq!(avg_total.sample_variance(), avg_left.sample_variance());
}
}