dygraphs/src/datahandler/bars.js

dygraphs is a fast, flexible open source JavaScript charting library.

/**
 * @license
 * Copyright 2013 David Eberlein (david.eberlein@ch.sauter-bc.com)
 * MIT-licenced: https://opensource.org/licenses/MIT
 */

/**
 * @fileoverview DataHandler base implementation for the "bar"
 * data formats. This implementation must be extended and the
 * extractSeries and rollingAverage must be implemented.
 * @author David Eberlein (david.eberlein@ch.sauter-bc.com)
 */

/*global Dygraph:false */
/*global DygraphLayout:false */
"use strict";

import DygraphDataHandler from './datahandler';
import DygraphLayout from '../dygraph-layout';

/**
 * @constructor
 * @extends {Dygraph.DataHandler}
 */
var BarsHandler = function() {
  DygraphDataHandler.call(this);
};
BarsHandler.prototype = new DygraphDataHandler();

// TODO(danvk): figure out why the jsdoc has to be copy/pasted from superclass.
//   (I get closure compiler errors if this isn't here.)
/**
 * @override
 * @param {!Array.<Array>} rawData The raw data passed into dygraphs where
 *     rawData[i] = [x,ySeries1,...,ySeriesN].
 * @param {!number} seriesIndex Index of the series to extract. All other
 *     series should be ignored.
 * @param {!DygraphOptions} options Dygraph options.
 * @return {Array.<[!number,?number,?]>} The series in the unified data format
 *     where series[i] = [x,y,{extras}].
 */
BarsHandler.prototype.extractSeries = function(rawData, seriesIndex, options) {
  // Not implemented here must be extended
};

/**
 * @override
 * @param {!Array.<[!number,?number,?]>} series The series in the unified
 *          data format where series[i] = [x,y,{extras}].
 * @param {!number} rollPeriod The number of points over which to average the data
 * @param {!DygraphOptions} options The dygraph options.
 * @param {!number} seriesIndex Index of the series this was extracted from.
 * TODO(danvk): be more specific than "Array" here.
 * @return {!Array.<[!number,?number,?]>} the rolled series.
 */
BarsHandler.prototype.rollingAverage =
    function(series, rollPeriod, options, seriesIndex) {
  // Not implemented here, must be extended.
};

/** @inheritDoc */
BarsHandler.prototype.onPointsCreated_ = function(series, points) {
  for (var i = 0; i < series.length; ++i) {
    var item = series[i];
    var point = points[i];
    point.y_top = NaN;
    point.y_bottom = NaN;
    point.yval_minus = DygraphDataHandler.parseFloat(item[2][0]);
    point.yval_plus = DygraphDataHandler.parseFloat(item[2][1]);
  }
};

/** @inheritDoc */
BarsHandler.prototype.getExtremeYValues = function(series, dateWindow, stepPlot) {
  var minY = null, maxY = null, y;

  var firstIdx = 0;
  var lastIdx = series.length - 1;

  for ( var j = firstIdx; j <= lastIdx; j++) {
    y = series[j][1];
    if (y === null || isNaN(y)) continue;

    var low = series[j][2][0];
    var high = series[j][2][1];

    if (low > y) low = y; // this can happen with custom bars,
    if (high < y) high = y; // e.g. in tests/custom-bars.html

    if (maxY === null || high > maxY) maxY = high;
    if (minY === null || low < minY) minY = low;
  }

  return [ minY, maxY ];
};

/** @inheritDoc */
BarsHandler.prototype.onLineEvaluated = function(points, axis, logscale) {
  var point;
  for (var j = 0; j < points.length; j++) {
    // Copy over the error terms
    point = points[j];
    point.y_top = DygraphLayout.calcYNormal_(axis, point.yval_minus, logscale);
    point.y_bottom = DygraphLayout.calcYNormal_(axis, point.yval_plus, logscale);
  }
};

export default BarsHandler;