Struct rand_distr::Uniform

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pub struct Uniform<X>(_)
where
    X: SampleUniform
;
Expand description

Sample values uniformly between two bounds.

Uniform::new and Uniform::new_inclusive construct a uniform distribution sampling from the given range; these functions may do extra work up front to make sampling of multiple values faster. If only one sample from the range is required, Rng::gen_range can be more efficient.

When sampling from a constant range, many calculations can happen at compile-time and all methods should be fast; for floating-point ranges and the full range of integer types this should have comparable performance to the Standard distribution.

Steps are taken to avoid bias which might be present in naive implementations; for example rng.gen::<u8>() % 170 samples from the range [0, 169] but is twice as likely to select numbers less than 85 than other values. Further, the implementations here give more weight to the high-bits generated by the RNG than the low bits, since with some RNGs the low-bits are of lower quality than the high bits.

Implementations must sample in [low, high) range for Uniform::new(low, high), i.e., excluding high. In particular, care must be taken to ensure that rounding never results values < low or >= high.

Example

use rand::distributions::{Distribution, Uniform};

let between = Uniform::from(10..10000);
let mut rng = rand::thread_rng();
let mut sum = 0;
for _ in 0..1000 {
    sum += between.sample(&mut rng);
}
println!("{}", sum);

For a single sample, Rng::gen_range may be preferred:

use rand::Rng;

let mut rng = rand::thread_rng();
println!("{}", rng.gen_range(0..10));

Implementations§

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impl<X> Uniform<X>where
    X: SampleUniform,

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pub fn new<B1, B2>(low: B1, high: B2) -> Uniform<X>where
    B1: SampleBorrow<X>,
    B2: SampleBorrow<X>,

Create a new Uniform instance which samples uniformly from the half open range [low, high) (excluding high). Panics if low >= high.

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pub fn new_inclusive<B1, B2>(low: B1, high: B2) -> Uniform<X>where
    B1: SampleBorrow<X>,
    B2: SampleBorrow<X>,

Create a new Uniform instance which samples uniformly from the closed range [low, high] (inclusive). Panics if low > high.

Trait Implementations§

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impl<X> Clone for Uniform<X>where
    X: Clone + SampleUniform,
    <X as SampleUniform>::Sampler: Clone,

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fn clone(&self) -> Uniform<X>

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl<X> Debug for Uniform<X>where
    X: Debug + SampleUniform,
    <X as SampleUniform>::Sampler: Debug,

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fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter. Read more
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impl<'de, X> Deserialize<'de> for Uniform<X>where
    X: SampleUniform,
    <X as SampleUniform>::Sampler: Deserialize<'de>,

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fn deserialize<__D>(
    __deserializer: __D
) -> Result<Uniform<X>, <__D as Deserializer<'de>>::Error>where
    __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer. Read more
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impl<X> Distribution<X> for Uniform<X>where
    X: SampleUniform,

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fn sample<R>(&self, rng: &mut R) -> Xwhere
    R: Rng + ?Sized,

Generate a random value of T, using rng as the source of randomness.
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fn sample_iter<R>(self, rng: R) -> DistIter<Self, R, T> where
    R: Rng,
    Self: Sized,

Create an iterator that generates random values of T, using rng as the source of randomness. Read more
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fn map<F, S>(self, func: F) -> DistMap<Self, F, T, S>where
    F: Fn(T) -> S,
    Self: Sized,

Create a distribution of values of ‘S’ by mapping the output of Self through the closure F Read more
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impl<X> From<Range<X>> for Uniform<X>where
    X: SampleUniform,

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fn from(r: Range<X>) -> Uniform<X>

Converts to this type from the input type.
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impl<X> From<RangeInclusive<X>> for Uniform<X>where
    X: SampleUniform,

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fn from(r: RangeInclusive<X>) -> Uniform<X>

Converts to this type from the input type.
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impl<X> PartialEq<Uniform<X>> for Uniform<X>where
    X: PartialEq<X> + SampleUniform,
    <X as SampleUniform>::Sampler: PartialEq<<X as SampleUniform>::Sampler>,

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fn eq(&self, other: &Uniform<X>) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl<X> Serialize for Uniform<X>where
    X: SampleUniform,
    <X as SampleUniform>::Sampler: Serialize,

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fn serialize<__S>(
    &self,
    __serializer: __S
) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error>where
    __S: Serializer,

Serialize this value into the given Serde serializer. Read more
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impl<X> Copy for Uniform<X>where
    X: Copy + SampleUniform,
    <X as SampleUniform>::Sampler: Copy,

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impl<X> StructuralPartialEq for Uniform<X>where
    X: SampleUniform,

Auto Trait Implementations§

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impl<X> RefUnwindSafe for Uniform<X>where
    <X as SampleUniform>::Sampler: RefUnwindSafe,

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impl<X> Send for Uniform<X>where
    <X as SampleUniform>::Sampler: Send,

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impl<X> Sync for Uniform<X>where
    <X as SampleUniform>::Sampler: Sync,

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impl<X> Unpin for Uniform<X>where
    <X as SampleUniform>::Sampler: Unpin,

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impl<X> UnwindSafe for Uniform<X>where
    <X as SampleUniform>::Sampler: UnwindSafe,

Blanket Implementations§

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impl<T> Any for Twhere
    T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for Twhere
    T: ?Sized,

const: unstable · source§

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere
    T: ?Sized,

const: unstable · source§

fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

const: unstable · source§

fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for Twhere
    U: From<T>,

const: unstable · source§

fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> ToOwned for Twhere
    T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for Twhere
    U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
const: unstable · source§

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for Twhere
    U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
const: unstable · source§

fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<V, T> VZip<V> for Twhere
    V: MultiLane<T>,

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fn vzip(self) -> V

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impl<T> DeserializeOwned for Twhere
    T: for<'de> Deserialize<'de>,