Struct linfa::dataset::Pr

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pub struct Pr(/* private fields */);

Expand description

Probability types

This helper struct exists to distinguish probabilities from floating points. For example SVM selects regression or classification training, based on the target type, and could not distinguish them without a new-type definition.

Implementations§

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impl Pr

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pub fn new(prob: f32) -> Self

Creates probability from the given float.

Panics

Panics if probability is negative or bigger than one.

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pub fn new_unchecked(prob: f32) -> Self

Creates probability from the given float. Doesn’t check whether it is negative or bigger than one.

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pub fn even() -> Pr

Methods from Deref<Target = f32>§

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pub const RADIX: u32 = 2u32

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pub const MANTISSA_DIGITS: u32 = 24u32

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pub const DIGITS: u32 = 6u32

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pub const EPSILON: f32 = 1.1920929E-7f32

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pub const MIN: f32 = -3.40282347E+38f32

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pub const MIN_POSITIVE: f32 = 1.17549435E-38f32

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pub const MAX: f32 = 3.40282347E+38f32

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pub const MIN_EXP: i32 = -125i32

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pub const MAX_EXP: i32 = 128i32

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pub const MIN_10_EXP: i32 = -37i32

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pub const MAX_10_EXP: i32 = 38i32

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pub const NAN: f32 = NaN_f32

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pub const INFINITY: f32 = +Inf_f32

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pub const NEG_INFINITY: f32 = -Inf_f32

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pub fn total_cmp(&self, other: &f32) -> Ordering

Return the ordering between self and other.

Unlike the standard partial comparison between floating point numbers, this comparison always produces an ordering in accordance to the totalOrder predicate as defined in the IEEE 754 (2008 revision) floating point standard. The values are ordered in the following sequence:

negative quiet NaN
negative signaling NaN
negative infinity
negative numbers
negative subnormal numbers
negative zero
positive zero
positive subnormal numbers
positive numbers
positive infinity
positive signaling NaN
positive quiet NaN.

The ordering established by this function does not always agree with the PartialOrd and PartialEq implementations of f32. For example, they consider negative and positive zero equal, while total_cmp doesn’t.

The interpretation of the signaling NaN bit follows the definition in the IEEE 754 standard, which may not match the interpretation by some of the older, non-conformant (e.g. MIPS) hardware implementations.

Example

struct GoodBoy {
    name: String,
    weight: f32,
}

let mut bois = vec![
    GoodBoy { name: "Pucci".to_owned(), weight: 0.1 },
    GoodBoy { name: "Woofer".to_owned(), weight: 99.0 },
    GoodBoy { name: "Yapper".to_owned(), weight: 10.0 },
    GoodBoy { name: "Chonk".to_owned(), weight: f32::INFINITY },
    GoodBoy { name: "Abs. Unit".to_owned(), weight: f32::NAN },
    GoodBoy { name: "Floaty".to_owned(), weight: -5.0 },
];

bois.sort_by(|a, b| a.weight.total_cmp(&b.weight));

// `f32::NAN` could be positive or negative, which will affect the sort order.
if f32::NAN.is_sign_negative() {
    assert!(bois.into_iter().map(|b| b.weight)
        .zip([f32::NAN, -5.0, 0.1, 10.0, 99.0, f32::INFINITY].iter())
        .all(|(a, b)| a.to_bits() == b.to_bits()))
} else {
    assert!(bois.into_iter().map(|b| b.weight)
        .zip([-5.0, 0.1, 10.0, 99.0, f32::INFINITY, f32::NAN].iter())
        .all(|(a, b)| a.to_bits() == b.to_bits()))
}