Enum Precision

pub enum Precision<T: Debug + Clone + PartialEq + Eq + PartialOrd> {
    Exact(T),
    Inexact(T),
    Absent,
}

Represents a value with a degree of certainty. Precision is used to propagate information the precision of statistical values.

Variants

Exact(T)

The exact value is known

Inexact(T)

The value is not known exactly, but is likely close to this value

Absent

Nothing is known about the value

Implementations

impl<T: Debug + Clone + PartialEq + Eq + PartialOrd> Precision<T>

pub fn get_value(&self) -> Option<&T>

If we have some value (exact or inexact), it returns that value. Otherwise, it returns None.

pub fn map<U, F>(self, f: F) -> Precision<U>

where F: Fn(T) -> U, U: Debug + Clone + PartialEq + Eq + PartialOrd,

Transform the value in this Precision object, if one exists, using the given function. Preserves the exactness state.

pub fn is_exact(&self) -> Option<bool>

Returns Some(true) if we have an exact value, Some(false) if we have an inexact value, and None if there is no value.

pub fn max(&self, other: &Precision<T>) -> Precision<T>

Returns the maximum of two (possibly inexact) values, conservatively propagating exactness information. If one of the input values is Precision::Absent, the result is Absent too.

pub fn min(&self, other: &Precision<T>) -> Precision<T>

Returns the minimum of two (possibly inexact) values, conservatively propagating exactness information. If one of the input values is Precision::Absent, the result is Absent too.

pub fn to_inexact(self) -> Self

Demotes the precision state from exact to inexact (if present).

impl Precision<usize>

pub fn add(&self, other: &Precision<usize>) -> Precision<usize>

Calculates the sum of two (possibly inexact) usize values, conservatively propagating exactness information. If one of the input values is Precision::Absent, the result is Absent too.

pub fn sub(&self, other: &Precision<usize>) -> Precision<usize>

Calculates the difference of two (possibly inexact) usize values, conservatively propagating exactness information. If one of the input values is Precision::Absent, the result is Absent too.

pub fn multiply(&self, other: &Precision<usize>) -> Precision<usize>

Calculates the multiplication of two (possibly inexact) usize values, conservatively propagating exactness information. If one of the input values is Precision::Absent, the result is Absent too.

pub fn with_estimated_selectivity(self, selectivity: f64) -> Self

Return the estimate of applying a filter with estimated selectivity selectivity to this Precision. A selectivity of 1.0 means that all rows are selected. A selectivity of 0.5 means half the rows are selected. Will always return inexact statistics.

impl Precision<ScalarValue>

pub fn add(&self, other: &Precision<ScalarValue>) -> Precision<ScalarValue>

Calculates the sum of two (possibly inexact) ScalarValue values, conservatively propagating exactness information. If one of the input values is Precision::Absent, the result is Absent too.

Trait Implementations

impl<T: Clone + Debug + Clone + PartialEq + Eq + PartialOrd> Clone for Precision<T>

fn clone(&self) -> Precision<T>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug + Clone + PartialEq + Eq + PartialOrd> Debug for Precision<T>

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

Formats the value using the given formatter.

impl<T: Debug + Clone + PartialEq + Eq + PartialOrd> Default for Precision<T>

fn default() -> Precision<T>

Returns the “default value” for a type.

impl<T: Debug + Clone + PartialEq + Eq + PartialOrd> Display for Precision<T>

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

Formats the value using the given formatter.

impl<T: PartialEq + Debug + Clone + PartialEq + Eq + PartialOrd> PartialEq for Precision<T>

fn eq(&self, other: &Precision<T>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T: Copy + Debug + Clone + PartialEq + Eq + PartialOrd> Copy for Precision<T>

impl<T: Eq + Debug + Clone + PartialEq + Eq + PartialOrd> Eq for Precision<T>

impl<T: Debug + Clone + PartialEq + Eq + PartialOrd> StructuralPartialEq for Precision<T>