Struct igraph_rng_t

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pub struct igraph_rng_t { /* private fields */ }

Implementations§

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impl igraph_rng_t

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pub fn new(kind: RngType, seed: u64) -> Result<Self>

Creates a new generator of the given type, seeded with seed (igraph_rng_init and igraph_rng_seed).

Two generators of the same type and seed produce the same numbers, on any thread:

use igraph::prelude::*;
// Pinned by igraph's own tests (`rng_init_destroy_max_bits_name_set_default.out`).
let mut mt = Rng::new(RngType::Mt19937, 42).unwrap();
let draws: Vec<i64> = (0..5).map(|_| mt.get_integer(0, 100)).collect();
assert_eq!(draws, vec![37, 80, 96, 18, 73]);

§Errors

ErrorKind::OutOfMemory if the state cannot be allocated.

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pub fn set_seed(&mut self, seed: u64) -> Result<()>

Re-seeds this generator (igraph_rng_seed): the numbers it produces afterwards depend only on its type and on seed.

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pub fn name(&self) -> String

The name of the algorithm, e.g. "MT19937", "LIBC", "PCG32" or "PCG64" (igraph_rng_name).

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pub fn get_integer(&mut self, min: i64, max: i64) -> i64

A uniform random integer in the closed interval [min, max] (igraph_rng_get_integer).

§Panics

If min > max.

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pub fn get_unif(&mut self, min: f64, max: f64) -> f64

A uniform random real in [min, max) (igraph_rng_get_unif).

§Panics

If a bound is not finite, max - min overflows, or min > max.

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pub fn get_unif01(&mut self) -> f64

A uniform random real in [0, 1) (igraph_rng_get_unif01).

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pub fn get_normal(&mut self, mean: f64, sd: f64) -> f64

A normally distributed random real with mean mean and standard deviation sd (igraph_rng_get_normal).

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pub fn get_bool(&mut self) -> bool

A random boolean (igraph_rng_get_bool).

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pub fn get_geom(&mut self, p: f64) -> f64

A geometric random number: the number of failures before the first success, with success probability p (igraph_rng_get_geom).

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pub fn get_binom(&mut self, n: i64, p: f64) -> f64

A binomial random number with n trials of probability p (igraph_rng_get_binom).

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pub fn get_exp(&mut self, rate: f64) -> f64

An exponential random number with the given rate (igraph_rng_get_exp).

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pub fn get_gamma(&mut self, shape: f64, scale: f64) -> f64

A gamma random number with the given shape and scale (igraph_rng_get_gamma).

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pub fn get_pois(&mut self, mean: f64) -> f64

A Poisson random number with the given mean (igraph_rng_get_pois).

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pub fn bits(&self) -> u32

Number of random bits produced at once by this generator (igraph_rng_bits).

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pub fn max(&self) -> u64

The largest integer this generator produces natively (igraph_rng_max).

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pub fn is_seeded(&self) -> bool

Whether the generator has been seeded (always true for generators created with Rng::new): the is_seeded flag that igraph_rng_seed sets, and that igraph_setup checks before seeding the default generator.

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pub fn scoped<R>(&mut self, f: impl FnOnce() -> R) -> R

Runs f with this generator installed as the thread’s default one (igraph_rng_set_default), restoring the previous default afterwards, even if f panics.

Every randomized igraph function called by f on this thread (and the free functions of this module) then draws from self; other threads are not affected.

use igraph::prelude::*;
let mut rng = Rng::new(RngType::Mt19937, 7).unwrap();
let x = rng.scoped(|| rng::integer(0, 1_000_000));
let mut again = Rng::new(RngType::Mt19937, 7).unwrap();
assert_eq!(again.scoped(|| rng::integer(0, 1_000_000)), x);

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impl igraph_rng_t

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pub fn sample_sphere_surface( &mut self, dim: usize, n: usize, radius: f64, positive: bool, ) -> Result<Vec<Vec<f64>>>

Like sample_sphere_surface, drawing from this generator (igraph_rng_sample_sphere_surface).

use igraph::prelude::*;
let mut a = Rng::new(RngType::Pcg64, 5)?;
let mut b = Rng::new(RngType::Pcg64, 5)?;
assert_eq!(a.sample_sphere_surface(4, 3, 1.0, false)?, b.sample_sphere_surface(4, 3, 1.0, false)?);