@antv/scale

What is @antv/scale?

@antv/scale is a JavaScript library for creating and managing scales, which are functions that map a domain of data values to a range of visual values. It is commonly used in data visualization to ensure that data is represented accurately and proportionally.

What are @antv/scale's main functionalities?

Linear Scale

Linear scales map a continuous domain to a continuous range. This is useful for data that is evenly distributed.

const { Linear } = require('@antv/scale');
const scale = new Linear({
  domain: [0, 100],
  range: [0, 1]
});
console.log(scale.map(50)); // 0.5

Ordinal Scale

Ordinal scales map a discrete domain to a discrete range. This is useful for categorical data.

const { Ordinal } = require('@antv/scale');
const scale = new Ordinal({
  domain: ['A', 'B', 'C'],
  range: [0, 1, 2]
});
console.log(scale.map('B')); // 1

Time Scale

Time scales map a time domain to a continuous range. This is useful for time-series data.

const { Time } = require('@antv/scale');
const scale = new Time({
  domain: [new Date(2020, 0, 1), new Date(2020, 11, 31)],
  range: [0, 1]
});
console.log(scale.map(new Date(2020, 5, 15))); // 0.5

Log Scale

Log scales map a logarithmic domain to a continuous range. This is useful for data that spans several orders of magnitude.

const { Log } = require('@antv/scale');
const scale = new Log({
  domain: [1, 100],
  range: [0, 1]
});
console.log(scale.map(10)); // 0.5

Other packages similar to @antv/scale

d3-scale

d3-scale is a part of the D3.js library and provides similar functionality for creating scales. It supports a wide range of scale types including linear, logarithmic, ordinal, and time scales. Compared to @antv/scale, d3-scale is more widely used and has a larger community, but @antv/scale may offer better integration with other AntV libraries.

vega-scale

vega-scale is part of the Vega visualization grammar and provides a variety of scale types for mapping data to visual values. It is similar to @antv/scale in terms of functionality but is designed to work within the Vega ecosystem. It offers robust support for different scale types and is well-documented.

README

@antv/scale

0.2 版本不兼容之前 0.1.X 版本

Description

scale 有很多中文名，标度、度量、比例尺等等。它是数据空间到图形空间的转换桥梁，负责将数据从数据空间（定义域）转换为图形属性空间区域（值域）。

例如：

或者

Attr

名称	类型	说明
type	string	scale 类型
values	any[]	定义域
min	any	定义域的最小值，在分类型 scale 中为序号
max	any	定义域的最大值
range	[number, number]	值域的最小、最大值
tickCount	number	期望的 tick 数量，非最终结果
formatter	func	格式化函数，用于 tooltip、tick 等展示
exponent	number	指数
base	number	对数底数

Methods

名称	类型	说明
scale	(value: any): number	将定义域的输入值转换为值域的输出值
invert	(scaled: number): any	将值域的输入值转换为定义域的输出值
translate	(value: any): number	分类型 scale 中，将定义域转化为序号
transform	(value: number): number	数值型 scale 中，对输入值的数学计算
clone	(): void	复制 scale 实例
getTicks	(): Tick[]	获取所有 ticks 集合
getText	(value: any): string	获取输入值的展示结果

Usage

import { getScale } from '@antv/scale';

const Linear = getScale('linear');

// 详情可参考单测用例
const scale = new Linear({
  min: 0,
  max: 100,
  range: [0, 1],
});