[][src]Struct rand::distributions::uniform::UniformInt

pub struct UniformInt<X> { /* fields omitted */ }

The back-end implementing [UniformSampler] for integer types.

Unless you are implementing [UniformSampler] for your own type, this type should not be used directly, use [Uniform] instead.

Implementation notes

For simplicity, we use the same generic struct UniformInt<X> for all integer types X. This gives us only one field type, X; to store unsigned values of this size, we take use the fact that these conversions are no-ops.

For a closed range, the number of possible numbers we should generate is range = (high - low + 1). To avoid bias, we must ensure that the size of our sample space, zone, is a multiple of range; other values must be rejected (by replacing with a new random sample).

As a special case, we use range = 0 to represent the full range of the result type (i.e. for new_inclusive($ty::MIN, $ty::MAX)).

The optimum zone is the largest product of range which fits in our (unsigned) target type. We calculate this by calculating how many numbers we must reject: reject = (MAX + 1) % range = (MAX - range + 1) % range. Any (large) product of range will suffice, thus in sample_single we multiply by a power of 2 via bit-shifting (faster but may cause more rejections).

The smallest integer PRNGs generate is u32. For 8- and 16-bit outputs we use u32 for our zone and samples (because it's not slower and because it reduces the chance of having to reject a sample). In this case we cannot store zone in the target type since it is too large, however we know ints_to_reject < range <= $unsigned::MAX.

An alternative to using a modulus is widening multiply: After a widening multiply by range, the result is in the high word. Then comparing the low word against zone makes sure our distribution is uniform.

Trait Implementations

impl UniformSampler for UniformInt<i8>[src]

type X = i8

The type sampled by this implementation.

impl UniformSampler for UniformInt<i16>[src]

type X = i16

The type sampled by this implementation.

impl UniformSampler for UniformInt<i32>[src]

type X = i32

The type sampled by this implementation.

impl UniformSampler for UniformInt<i64>[src]

type X = i64

The type sampled by this implementation.

impl UniformSampler for UniformInt<i128>[src]

type X = i128

The type sampled by this implementation.

impl UniformSampler for UniformInt<isize>[src]

type X = isize

The type sampled by this implementation.

impl UniformSampler for UniformInt<u8>[src]

type X = u8

The type sampled by this implementation.

impl UniformSampler for UniformInt<u16>[src]

type X = u16

The type sampled by this implementation.

impl UniformSampler for UniformInt<u32>[src]

type X = u32

The type sampled by this implementation.

impl UniformSampler for UniformInt<u64>[src]

type X = u64

The type sampled by this implementation.

impl UniformSampler for UniformInt<usize>[src]

type X = usize

The type sampled by this implementation.

impl UniformSampler for UniformInt<u128>[src]

type X = u128

The type sampled by this implementation.

impl<X: Clone> Clone for UniformInt<X>[src]

fn clone_from(&mut self, source: &Self)1.0.0[src]

Performs copy-assignment from source. Read more

impl<X: Copy> Copy for UniformInt<X>[src]

impl<X: Debug> Debug for UniformInt<X>[src]

Auto Trait Implementations

impl<X> Send for UniformInt<X> where
    X: Send

impl<X> Sync for UniformInt<X> where
    X: Sync

Blanket Implementations

impl<T> From<T> for T[src]

impl<T> ToOwned for T where
    T: Clone
[src]

type Owned = T

The resulting type after obtaining ownership.

impl<T, U> Into<U> for T where
    U: From<T>, 
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impl<T, U> TryFrom<U> for T where
    U: Into<T>, 
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type Error = Infallible

The type returned in the event of a conversion error.

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, 
[src]

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

The type returned in the event of a conversion error.

impl<T> BorrowMut<T> for T where
    T: ?Sized
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impl<T> Borrow<T> for T where
    T: ?Sized
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impl<T> Any for T where
    T: 'static + ?Sized
[src]

impl<V, T> VZip<V> for T where
    V: MultiLane<T>, 
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