quantize.md

Quantize

Similar to threshold scales, but computed cut values based on size of each data. (online demo)

Usage

import { Quantize, QuantizeOptions } from '@antv/scale';

const options: QuantizeOptions = {
  range: ['a', 'b' ,'c'],
};

const x = new Quantize(options);

x.map(0); // 'a'
x.map(0.2); // 'a'
x.map(0.4); // 'b'
x.map(0.6); // 'b'
x.map(0.8); // 'c'
x.map(1); // 'c'

x.invert('a'); // [undefined, 1 / 3]
x.invert('b'); // [1 / 3, 2 / 3]
x.invert('c'); // [2 / 3, undefined]
x.invert('d'); // [undefined,undefined]

x.getThresholds(); // [1 / 3, 2 / 3]

Options

Key	Description	Type	Default
domain	Sets the scale’s domain to the specified two-element array of values. The values must be in ascending order.	number[]	[0, 1]
range	Sets the scale’s range to the specified array of values.	any[]	[0.5]
unknown	Sets the output value of the scale for undefined (or NaN) input values.	any	undefined
nice	Extends the domain so that it starts and ends on nice round values if it is true.	boolean	false
tickCount	Sets approximately count representative values from the scale’s domain. The specified tickCount in options is only a hint: the scale may return more or fewer values depending on the domain.	number	5
tickMethod	Sets the method for computing representative values from the scale’s domain.	(min: number, max: number, count: number) => number[]	wilkinson-extended

Methods

# map(x: number): any

Given a value in the input domain, returns the corresponding value in the output range if it is not undefined (or NaN), otherwise options.unknown.

# invert(x: any): (number | undefined)[]

Returns the extent of values in the domain [x0, x1] for the corresponding value in the range, representing the inverse mapping from range to domain.

# update(options: QuantizeOptions): void

Update the scale's options and rescale.

# getOptions(): QuantizeOptions

Returns the scale's current options.

# clone(): Quantize

Returns a new quantize scale with the independent and same options as the original one.

# getTicks(): number[]

Returns a series of representative values from the scale’s domain.

# getThresholds(): number[]

Returns the array of computed thresholds within the domain.