package.src.lib.to_log_range.js Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of plotly.js Show documentation

The open source javascript graphing library that powers plotly

The newest version!

'use strict';

var isNumeric = require('fast-isnumeric');

/**
 * convert a linear value into a logged value, folding negative numbers into
 * the given range
 */
module.exports = function toLogRange(val, range) {
    if(val > 0) return Math.log(val) / Math.LN10;

    // move a negative value reference to a log axis - just put the
    // result at the lowest range value on the plot (or if the range also went negative,
    // one millionth of the top of the range)
    var newVal = Math.log(Math.min(range[0], range[1])) / Math.LN10;
    if(!isNumeric(newVal)) newVal = Math.log(Math.max(range[0], range[1])) / Math.LN10 - 6;
    return newVal;
};