@antv/scale/src/scales/log.ts

Toolkit for mapping abstract data into visual representation.

import { Continuous } from './continuous';
import { LogOptions, TickMethodOptions } from '../types';
import { createInterpolateValue, logs, pows } from '../utils';
import { d3Log } from '../tick-methods/d3-log';
import { d3LogNice } from '../utils/d3-log-nice';

/**
 * Linear 比例尺
 *
 * 构造一个线性的对数比例尺
 */
export class Log extends Continuous<LogOptions> {
  protected getDefaultOptions(): LogOptions {
    return {
      domain: [1, 10],
      range: [0, 1],
      base: 10,
      interpolate: createInterpolateValue,
      tickMethod: d3Log,
      tickCount: 5,
    };
  }

  protected chooseNice() {
    return d3LogNice;
  }

  protected getTickMethodOptions(): TickMethodOptions<number> {
    const { domain, tickCount, base } = this.options;
    const min = domain[0];
    const max = domain[domain.length - 1];
    return [min, max, tickCount, base];
  }

  protected chooseTransforms() {
    const { base, domain } = this.options;
    const shouldReflect = domain[0] < 0;
    return [logs(base, shouldReflect), pows(base, shouldReflect)];
  }

  public clone(): Log {
    return new Log(this.options);
  }
}