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/**
* The Candle chart plotter is adapted from code written by
* Zhenlei Cai (jpenguin@gmail.com)
* https://github.com/danvk/dygraphs/pull/141/files
*
* Adapted for use by dyGroup in the dygraphs R package
*
*/
function candlestickgroupPlotter(e) {
// BEGIN HEADER BLOCK
// This first block can be copied to other plotters to capture the group
var g = e.dygraph;
var group;
var groupIdx = [];
var sets = [];
var allSets = e.allSeriesPoints;
var minIdx = Infinity;
var setName = e.setName;
var setNames = g.getLabels().slice(1);
var currGroup = g.attr_("group", setName);
for (var setIdx = 0; setIdx < allSets.length; setIdx++) {
// get the name and group of the current setIdx
setName = setNames[setIdx];
group = g.attr_("group", setName);
if (group === currGroup) {
//save the indv index and the points
groupIdx.push(setIdx);
sets.push(allSets[setIdx]);
// capturing the min indx helps to ensure we don't render the plotter
// multiple times
if (setIdx < minIdx) minIdx = setIdx;
}
}
// We'll employ the plotter only on the first of the group
if (e.seriesIndex !== minIdx) return;
// END HEADER BLOCK
// If the group doesn't have four series then revert to prior
if (groupIdx.length < 4) return;
function getPrices(sets) {
var prices = [];
var price;
for (var p = 0 ; p < sets[0].length; p++) {
price = {
open : sets[0][p].yval,
high : sets[1][p].yval,
low : sets[2][p].yval,
close : sets[3][p].yval,
openY : sets[0][p].y,
highY : sets[1][p].y,
lowY : sets[2][p].y,
closeY : sets[3][p].y
};
prices.push(price);
}
return prices;
}
var prices = getPrices(sets);
var area = e.plotArea;
var ctx = e.drawingContext;
ctx.strokeStyle = '#202020';
ctx.lineWidth = 0.6;
var minBarWidth = 2;
var numBars = prices.length + 1; // To compensate the probably removed first "incomplete" bar
var barWidth = Math.round((area.w / numBars) / 2);
if (barWidth % 2 !== 0) {
barWidth++;
}
barWidth = Math.max(barWidth, minBarWidth);
var price;
for (var p = 0 ; p < prices.length; p++) {
ctx.beginPath();
price = prices[p];
var topY = area.h * price.highY + area.y;
var bottomY = area.h * price.lowY + area.y;
var centerX = Math.floor(area.x + sets[0][p].x * area.w) + 0.5; // crisper rendering
ctx.moveTo(centerX, topY);
ctx.lineTo(centerX, bottomY);
ctx.closePath();
ctx.stroke();
var bodyY;
if (price.open > price.close) {
ctx.fillStyle ='#d9534f';
bodyY = area.h * price.openY + area.y;
}
else {
ctx.fillStyle ='#5cb85c';
bodyY = area.h * price.closeY + area.y;
}
var bodyHeight = area.h * Math.abs(price.openY - price.closeY);
ctx.fillRect(centerX - barWidth / 2, bodyY, barWidth, bodyHeight);
}
}
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