Function findExtremes

src/plots/cartesian/autorange.js:450–555

* findExtremes * * Find min/max extremes of an array of coordinates on a given axis. * * Note that findExtremes is called during `calc`, when we don't yet know the axis * length; all the inputs should be based solely on the trace data, nothing * about the axis layout. * * Note that `ppad` an

(ax, data, opts)

 *  - opts {object}: a ref to the passed "options" object
 */
function findExtremes(ax, data, opts) {
    if(!opts) opts = {};
    if(!ax._m) ax.setScale();

    var minArray = [];
    var maxArray = [];

    var len = data.length;
    var extrapad = opts.padded || false;
    var tozero = opts.tozero && (ax.type === 'linear' || ax.type === '-');
    var isLog = ax.type === 'log';
    var hasArrayOption = false;
    var vpadLinearized = opts.vpadLinearized || false;
    var i, v, di, dmin, dmax, ppadiplus, ppadiminus, vmin, vmax;

    function makePadAccessor(item) {
        if(Array.isArray(item)) {
            hasArrayOption = true;
            return function(i) { return Math.max(Number(item[i]||0), 0); };
        } else {
            var v = Math.max(Number(item||0), 0);
            return function() { return v; };
        }
    }

    var ppadplus = makePadAccessor((ax._m > 0 ?
        opts.ppadplus : opts.ppadminus) || opts.ppad || 0);
    var ppadminus = makePadAccessor((ax._m > 0 ?
        opts.ppadminus : opts.ppadplus) || opts.ppad || 0);
    var vpadplus = makePadAccessor(opts.vpadplus || opts.vpad);
    var vpadminus = makePadAccessor(opts.vpadminus || opts.vpad);

    if(!hasArrayOption) {
        // with no arrays other than `data` we don't need to consider
        // every point, only the extreme data points
        vmin = Infinity;
        vmax = -Infinity;

        if(isLog) {
            for(i = 0; i < len; i++) {
                v = data[i];
                // data is not linearized yet so we still have to filter out negative logs
                if(v < vmin && v > 0) vmin = v;
                if(v > vmax && v < FP_SAFE) vmax = v;
            }
        } else {
            for(i = 0; i < len; i++) {
                v = data[i];
                if(v < vmin && v > -FP_SAFE) vmin = v;
                if(v > vmax && v < FP_SAFE) vmax = v;
            }
        }

        data = [vmin, vmax];
        len = 2;
    }

    var collapseOpts = {tozero: tozero, extrapad: extrapad};