log_ticker.ts

import {TickSpec} from "./ticker"
import {AdaptiveTicker} from "./adaptive_ticker"
import {range} from "core/util/array"
import * as p from "core/properties"

export namespace LogTicker {
  export type Attrs = p.AttrsOf<Props>

  export type Props = AdaptiveTicker.Props
}

export interface LogTicker extends LogTicker.Attrs {}

export class LogTicker extends AdaptiveTicker {
  override properties: LogTicker.Props

  constructor(attrs?: Partial<LogTicker.Attrs>) {
    super(attrs)
  }

  static init_LogTicker(): void {
    this.override<LogTicker.Props>({
      mantissas: [1, 5],
    })
  }

  override get_ticks_no_defaults(data_low: number, data_high: number, _cross_loc: number, desired_n_ticks: number): TickSpec<number> {
    const num_minor_ticks = this.num_minor_ticks
    const minor_ticks = []

    const base = this.base

    const log_low = Math.log(data_low) / Math.log(base)
    const log_high = Math.log(data_high) / Math.log(base)
    const log_interval = log_high - log_low

    let ticks: number[]

    if (!isFinite(log_interval)) {
      ticks = []
    } else if (log_interval < 2) { // treat as linear ticker
      const interval = this.get_interval(data_low, data_high, desired_n_ticks)
      const start_factor = Math.floor(data_low / interval)
      const end_factor   = Math.ceil(data_high / interval)

      ticks = range(start_factor, end_factor + 1)
        .filter((factor) => factor != 0)
        .map((factor) => factor*interval)
        .filter((tick) => data_low <= tick && tick <= data_high)

      if (num_minor_ticks > 0 && ticks.length > 0) {
        const minor_interval = interval / num_minor_ticks
        const minor_offsets = range(0, num_minor_ticks).map((i) => i*minor_interval)
        for (const x of minor_offsets.slice(1)) {
          minor_ticks.push(ticks[0] - x)
        }
        for (const tick of ticks) {
          for (const x of minor_offsets) {
            minor_ticks.push(tick + x)
          }
        }
      }
    } else {
      const startlog = Math.ceil(log_low * 0.999999)
      const endlog = Math.floor(log_high * 1.000001)
      const interval = Math.ceil((endlog - startlog) / 9.0)

      ticks = range(startlog-1, endlog+1, interval)
        .map((i) => base**i)

      if (num_minor_ticks > 0 && ticks.length > 0) {
        const minor_interval = base**interval / num_minor_ticks
        const minor_offsets = range(1, num_minor_ticks+1).map((i) => i*minor_interval)
        for (const x of minor_offsets) {
          minor_ticks.push(ticks[0] / x)
        }
        minor_ticks.push(ticks[0])
        for (const tick of ticks) {
          for (const x of minor_offsets) {
            minor_ticks.push(tick * x)
          }
        }
      }
    }

    return {
      major: ticks.filter((tick) => data_low <= tick && tick <= data_high),
      minor: minor_ticks.filter((tick) => data_low <= tick && tick <= data_high),
    }
  }
}