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consider 'log' progression for scale-y #3

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consider 'log' progression for scale-y #3

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8551785
consider 'log' progression for scale-y
splendido Jan 26, 2016
8269ac9
now ignoring nulls and non-numbers in trendlines computation
splendido Jan 29, 2016
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62 changes: 40 additions & 22 deletions zingchart.jquery.js
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Original file line number Diff line number Diff line change
Expand Up @@ -1459,40 +1459,62 @@
$.fn.drawTrendline = function (opts) {
var myId = this[0].id;
calculate.call(this,0);

function calculate(pindex) {
var nodes = $(this).getSeriesValues({
plotindex:pindex
});
var sxy = 0, sx = 0, sy = 0, sx2 = 0, l = 0;
var oScaleInfo = $(this).getObjectInfo({
object : 'scale',
name : 'scale-x'
});
var scaleY = $(this).getObjectInfo({
object:'scale',
name: 'scale-y'
});

var logScale = (scaleY.progression === "log");
var log = Math.log;
var aScaleValues = oScaleInfo.values;
var node, x, y;
var sxy = 0, sx = 0, sy = 0, sx2 = 0, l = 0;
for (var i=0;i<nodes.length;i++) {
if (nodes[i][1] != undefined && typeof(nodes[i][1]) == 'number') {
sxy += nodes[i][0]*nodes[i][1];
sx += nodes[i][0];
sy += nodes[i][1];
sx2 += nodes[i][0]*nodes[i][0];
l++;
node = nodes[i];
if (node[1] != undefined && typeof(node[1]) == 'number') {
x = node[0];
y = node[1];
}
else {
sxy += nodes[i]*aScaleValues[i];
sx += aScaleValues[i];
sy += nodes[i];
sx2 += Math.pow(aScaleValues[i],2);
x = aScaleValues[i];
y = node;
}

if (typeof x === "number" && isFinite(x) && typeof y === "number" && isFinite(y)) {
if (logScale) {
y = log(y);
}

sxy += x*y;
sx += x;
sy += y;
sx2 += x*x;
l++;
}
}

var b = (l * sxy - sx * sy) / (l * sx2 - sx * sx);
var a = (sy - b * sx) / l;
var oScaleInfo = $(this).getObjectInfo({
object : 'scale',
name : 'scale-x'
});
var aScaleValues = oScaleInfo.values, fScaleMin = aScaleValues[0], fScaleMax = aScaleValues[aScaleValues.length-1];
var aRange = [a + b*fScaleMin, a + b*fScaleMax];
var aScaleValues = oScaleInfo.values,
fScaleMin = aScaleValues[0],
fScaleMax = aScaleValues[aScaleValues.length-1];
var aRange;

aRange = [a + b*fScaleMin, a + b*fScaleMax];
if (logScale) {
aRange[0] = Math.exp(aRange[0]);
aRange[1] = Math.exp(aRange[1]);
}

var trendline = {
type : 'line',
lineColor : '#c00',
Expand All @@ -1507,10 +1529,6 @@
$.extend(trendline,opts);
}
trendline.range = aRange;
var scaleY = $(this).getObjectInfo({
object:'scale',
name: 'scale-y'
});
var markers = scaleY.markers;
if (markers) {
markers.push(trendline);
Expand All @@ -1529,4 +1547,4 @@
return this;
};

}( jQuery ));
}( jQuery ));