dygraphs/src/datahandler/default.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 default implementation used for simple line charts.
 * @author David Eberlein (david.eberlein@ch.sauter-bc.com)
 */

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

import DygraphDataHandler from './datahandler';

/**
 * @constructor
 * @extends Dygraph.DataHandler
 */
var DefaultHandler = function() {
};

DefaultHandler.prototype = new DygraphDataHandler();

/** @inheritDoc */
DefaultHandler.prototype.extractSeries = function(rawData, i, options) {
  // TODO(danvk): pre-allocate series here.
  var series = [];
  const seriesLabel = options.get("labels")[i];
  const logScale = options.getForSeries("logscale", seriesLabel);
  for ( var j = 0; j < rawData.length; j++) {
    var x = rawData[j][0];
    var point = rawData[j][i];
    if (logScale) {
      // On the log scale, points less than zero do not exist.
      // This will create a gap in the chart.
      if (point <= 0) {
        point = null;
      }
    }
    series.push([ x, point ]);
  }
  return series;
};

/** @inheritDoc */
DefaultHandler.prototype.rollingAverage = function(originalData, rollPeriod,
    options, i) {
  rollPeriod = Math.min(rollPeriod, originalData.length);
  var rollingData = [];

  var i, j, y, sum, num_ok;
  // Calculate the rolling average for the first rollPeriod - 1 points
  // where
  // there is not enough data to roll over the full number of points
  if (rollPeriod == 1) {
    return originalData;
  }
  for (i = 0; i < originalData.length; i++) {
    sum = 0;
    num_ok = 0;
    for (j = Math.max(0, i - rollPeriod + 1); j < i + 1; j++) {
      y = originalData[j][1];
      if (y === null || isNaN(y))
        continue;
      num_ok++;
      sum += originalData[j][1];
    }
    if (num_ok) {
      rollingData[i] = [ originalData[i][0], sum / num_ok ];
    } else {
      rollingData[i] = [ originalData[i][0], null ];
    }
  }

  return rollingData;
};

/** @inheritDoc */
DefaultHandler.prototype.getExtremeYValues = function getExtremeYValues(series, dateWindow, stepPlot) {
  var minY = null, maxY = null, y;
  var firstIdx = 0, lastIdx = series.length - 1;

  for ( var j = firstIdx; j <= lastIdx; j++) {
    y = series[j][1];
    if (y === null || isNaN(y))
      continue;
    if (maxY === null || y > maxY) {
      maxY = y;
    }
    if (minY === null || y < minY) {
      minY = y;
    }
  }
  return [ minY, maxY ];
};

export default DefaultHandler;