log

Overview

The logarithmic scale (log scale) in G2 uses logarithmic functions for data mapping, based on exponential relationships with non-linear distribution, specifically designed for data showing exponential growth. When the numerical range in data spans a very large range and causes parts of the chart to be too dense or have too much blank space, logarithmic scale should be prioritized.

Based on the mathematical formula y = log(base) + b.

Linear Scale
Logarithmic Scale (log scale)

Usage

import { Chart } from '@antv/g2';

const chart = new Chart({
  container: 'container',
});

chart.options({
  type: 'view',
  autoFit: true,
  height: 300,
  data: [
    { year: '1991', value: 1 },
    { year: '1992', value: 10 },
    { year: '1993', value: 100 },
    { year: '1994', value: 1000 },
    { year: '1995', value: 10000 },
  ],
  encode: { x: 'year', y: 'value' },
  scale: {
    y: {
      type: 'log',
      // Tick count
      tickCount: 5,
      // Generate uniform ticks
      tickMethod: (min, max, count, base) => {
        // Calculate logarithmic range
        const logMin = Math.log(min) / Math.log(base);
        const logMax = Math.log(max) / Math.log(base);

        // Calculate logarithmic step
        const logStep = (logMax - logMin) / (count - 1);

        // Generate tick array
        const ticks = [];
        for (let i = 0; i < count; i++) {
          const logValue = logMin + i * logStep;
          const value = Math.pow(base, logValue);
          // Filter values outside the range
          if (value >= min && value <= max) {
            ticks.push(Math.round(value));
          }
        }
        return ticks;
      },
    },
  },
  children: [
    { type: 'line', labels: [{ text: 'value', style: { dx: -10, dy: -12 } }] },
    { type: 'point', style: { fill: 'white' }, tooltip: false },
  ],
});

chart.render(); // Render chart

Options

Property	Description	Type	Default Value
domain	Set the domain range of the data	`number[]`	Min and max range of input data
domainMin	Set the minimum value of the data domain	`number`	Minimum value of input data
domainMax	Set the maximum value of the data domain	`number`	Maximum value of input data
range	Set the range of mapped values	`number[]` \| `string[]`	`[0, 1]`
rangeMin	Set the minimum value of the mapped range	`number \| string`	`0`
rangeMax	Set the maximum value of the mapped range	`number \| string`	`1`
unknown	Return value for `undefined`, `NaN`, `null` empty values	`any`	`undefined`
tickCount	Set the recommended number of ticks to generate; tickCount is only a suggestion	`number`	`5`
tickMethod	Set the method for generating ticks, commonly used for custom ticks	`(min: number, max: number, count: number) => number[]`	`calculateLogTicks`
round	Round output values	`boolean`	`false`
clamp	Limit mapped values to the range	`boolean`	`false`
nice	Extend domain range to make output ticks display more friendly	`boolean`	`false`
interpolate	Custom interpolation function	`(a: number, b: number) => (t: number) => T`	`(a, b) => (t) => a * (1 - t) + b * t`
base	Set the logarithmic base	`number`	`10`

Configuration and notes:

{
  scale: {
    y: {
      type: 'log', // Note: Do not use log when data returns both positive and negative values.
      domainMin: 10,
      domainMax: 1000,
      base: 100, // Set base to 100,
    }
  }
}

If you need a minimum value domainMin: 0, please refer to the Chart Examples - Logarithmic Column Chart page.

Examples

Format conversion to `linear`

import { Chart } from '@antv/g2';

const chart = new Chart({
  container: 'container',
});

chart.options({
  type: 'view',
  autoFit: true,
  height: 300,
  data: [
    { year: '1991', value: 1 },
    { year: '1992', value: 10 },
    { year: '1993', value: 1000 },
    { year: '1994', value: 0.1 },
    { year: '1995', value: 100 },
  ],
  encode: { x: 'year', y: 'value' },
  scale: { x: { range: [0, 1] }, y: { type: 'log', tickCount: 4 } },
  axis: {
    y: {
      labelFormatter: (v) => {
        return Math.log10(v) + 1;
      },
    },
  },
  children: [
    {
      type: 'line',
      labels: [
        {
          text: 'value',
          formatter: (v) => {
            return Math.log10(v) + 1;
          },
          style: { dx: -10, dy: -12 },
        },
      ],
    },
    { type: 'point', style: { fill: 'white' }, tooltip: false },
  ],
});

chart.render(); // Render chart

log

Overview

Usage

Options

Examples

Format conversion to linear

Format conversion to `linear`