criterion/stats/univariate/
resamples.rs

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1use std::mem;
2
3use crate::stats::float::Float;
4use crate::stats::rand_util::{new_rng, Rng};
5use crate::stats::univariate::Sample;
6
7pub struct Resamples<'a, A>
8where
9    A: Float,
10{
11    rng: Rng,
12    sample: &'a [A],
13    stage: Option<Vec<A>>,
14}
15
16#[cfg_attr(feature = "cargo-clippy", allow(clippy::should_implement_trait))]
17impl<'a, A> Resamples<'a, A>
18where
19    A: 'a + Float,
20{
21    pub fn new(sample: &'a Sample<A>) -> Resamples<'a, A> {
22        let slice = sample;
23
24        Resamples {
25            rng: new_rng(),
26            sample: slice,
27            stage: None,
28        }
29    }
30
31    pub fn next(&mut self) -> &Sample<A> {
32        let n = self.sample.len();
33        let rng = &mut self.rng;
34
35        match self.stage {
36            None => {
37                let mut stage = Vec::with_capacity(n);
38
39                for _ in 0..n {
40                    let idx = rng.rand_range(0u64..(self.sample.len() as u64));
41                    stage.push(self.sample[idx as usize])
42                }
43
44                self.stage = Some(stage);
45            }
46            Some(ref mut stage) => {
47                for elem in stage.iter_mut() {
48                    let idx = rng.rand_range(0u64..(self.sample.len() as u64));
49                    *elem = self.sample[idx as usize]
50                }
51            }
52        }
53
54        if let Some(ref v) = self.stage {
55            unsafe { mem::transmute::<&[_], _>(v) }
56        } else {
57            unreachable!();
58        }
59    }
60}
61
62#[cfg(test)]
63mod test {
64    use quickcheck::quickcheck;
65    use quickcheck::TestResult;
66    use std::collections::HashSet;
67
68    use crate::stats::univariate::resamples::Resamples;
69    use crate::stats::univariate::Sample;
70
71    // Check that the resample is a subset of the sample
72    quickcheck! {
73        fn subset(size: u8, nresamples: u8) -> TestResult {
74            let size = size as usize;
75            let nresamples = nresamples as usize;
76            if size > 1 {
77                let v: Vec<_> = (0..size).map(|i| i as f32).collect();
78                let sample = Sample::new(&v);
79                let mut resamples = Resamples::new(sample);
80                let sample = v.iter().map(|&x| x as i64).collect::<HashSet<_>>();
81
82                TestResult::from_bool((0..nresamples).all(|_| {
83                    let resample = resamples.next()
84
85                        .iter()
86                        .map(|&x| x as i64)
87                        .collect::<HashSet<_>>();
88
89                    resample.is_subset(&sample)
90                }))
91            } else {
92                TestResult::discard()
93            }
94        }
95    }
96
97    #[test]
98    fn different_subsets() {
99        let size = 1000;
100        let v: Vec<_> = (0..size).map(|i| i as f32).collect();
101        let sample = Sample::new(&v);
102        let mut resamples = Resamples::new(sample);
103
104        // Hypothetically, we might see one duplicate, but more than one is likely to be a bug.
105        let mut num_duplicated = 0;
106        for _ in 0..1000 {
107            let sample_1 = resamples.next().iter().cloned().collect::<Vec<_>>();
108            let sample_2 = resamples.next().iter().cloned().collect::<Vec<_>>();
109
110            if sample_1 == sample_2 {
111                num_duplicated += 1;
112            }
113        }
114
115        if num_duplicated > 1 {
116            panic!("Found {} duplicate samples", num_duplicated);
117        }
118    }
119}
criterion/stats/univariate/resamples.rs

criterion/stats/univariate/
resamples.rs
