47 lines
957 B
Rust
47 lines
957 B
Rust
use rand::{Rng,weak_rng};
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struct SofN<R: Rng+Sized, T> {
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rng: R,
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sample: Vec<T>,
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i: usize,
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n: usize,
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}
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impl<R: Rng, T> SofN<R, T> {
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fn new(rng: R, n: usize) -> Self {
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SofN{rng, sample: Vec::new(), i: 0, n}
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}
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fn add(&mut self, item: T) {
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self.i += 1;
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if self.i <= self.n {
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self.sample.push(item);
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} else if self.rng.gen_range(0, self.i) < self.n {
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self.sample[self.rng.gen_range(0, self.n)] = item;
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}
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}
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fn sample(&self) -> &Vec<T> {
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&self.sample
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}
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}
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pub fn main() {
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const MAX: usize = 10;
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let mut bin: [i32; MAX] = Default::default();
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for _ in 0..100000 {
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let mut s_of_n = SofN::new(weak_rng(), 3);
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for i in 0..MAX { s_of_n.add(i); }
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for s in s_of_n.sample() {
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bin[*s] += 1;
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}
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}
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for (i, x) in bin.iter().enumerate() {
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println!("frequency of {}: {}", i, x);
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}
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}
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