Enum Scale 

pub enum Scale {
    Linear {
        domain: (f64, f64),
        range: (f32, f32),
    },
    Log {
        domain: (f64, f64),
        range: (f32, f32),
        base: f64,
    },
    Band {
        domain: Vec<String>,
        range: (f32, f32),
        padding: f32,
    },
    Time {
        domain: (i64, i64),
        range: (f32, f32),
    },
    Sqrt {
        domain: (f64, f64),
        range: (f32, f32),
    },
    Power {
        domain: (f64, f64),
        range: (f32, f32),
        exponent: f64,
    },
    Symlog {
        domain: (f64, f64),
        range: (f32, f32),
        constant: f64,
    },
    Ordinal {
        domain: Vec<String>,
        range: Vec<f32>,
    },
}

A scale maps data values to visual coordinates.

Data stays f64 (scientific precision) until mapped through a Scale to f32 visual coordinates.

Variants

Linear

Linear mapping.

Fields

domain: (f64, f64)

Data domain (min, max).

range: (f32, f32)

Visual range (min, max) in pixels.

Log

Logarithmic mapping.

Fields

domain: (f64, f64)

Data domain (min, max) — must be positive.

range: (f32, f32)

Visual range (min, max).

base: f64

Log base (typically 10 or e).

Band

Band scale for categorical data.

Fields

domain: Vec<String>

Category labels.

range: (f32, f32)

Visual range.

padding: f32

Padding between bands as fraction [0, 1).

Time

Time scale (Unix milliseconds).

Fields

domain: (i64, i64)

Domain as Unix ms (start, end).

range: (f32, f32)

Visual range.

Sqrt

Square root mapping (emphasizes smaller values).

Fields

domain: (f64, f64)

Data domain (min, max).

range: (f32, f32)

Visual range.

Power

Power mapping with configurable exponent.

Fields

domain: (f64, f64)

Data domain (min, max).

range: (f32, f32)

Visual range.

exponent: f64

Exponent (1 = linear, 2 = quadratic, 0.5 = sqrt).

Symlog

Symmetric log: handles positive, negative, and zero.

Fields

domain: (f64, f64)

Data domain (min, max).

range: (f32, f32)

Visual range.

constant: f64

Linearity threshold constant.

Ordinal

Ordinal: maps discrete string values to specific positions.

Fields

domain: Vec<String>

Ordered labels.

range: Vec<f32>

Corresponding pixel positions.

Implementations

impl Scale

pub fn map(&self, value: f64) -> f32

Map a continuous data value to a visual coordinate.

pub fn map_band(&self, category: &str) -> Option<(f32, f32)>

Map a band category to its center position and width.

pub fn invert(&self, visual: f32) -> f64

Invert: map from visual coordinate back to data value.

pub fn ticks(&self, target_count: usize) -> Vec<f64>

Generate nice tick positions.

pub fn nice(&self, target_count: usize) -> Self

Extend the domain to nice round boundaries so ticks align with domain edges.

For Linear scales, this expands the domain outward to the nearest nice tick boundaries using D3-style tick step computation. After nicing, ticks() will never produce values outside the domain.

pub fn format_tick(&self, value: f64) -> String

Format a tick value as a label.

Trait Implementations

impl Clone for Scale

fn clone(&self) -> Scale

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Scale

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

Formats the value using the given formatter.