/* Flot plugin for plotting error bars.
Copyright (c) 2007-2014 IOLA and Ole Laursen.
Licensed under the MIT license.
Error bars are used to show standard deviation and other statistical
properties in a plot.
* Created by Rui Pereira - rui (dot) pereira (at) gmail (dot) com
This plugin allows you to plot error-bars over points. Set "errorbars" inside
the points series to the axis name over which there will be error values in
your data array (*even* if you do not intend to plot them later, by setting
"show: null" on xerr/yerr).
The plugin supports these options:
series: {
points: {
errorbars: "x" or "y" or "xy",
xerr: {
show: null/false or true,
asymmetric: null/false or true,
upperCap: null or "-" or function,
lowerCap: null or "-" or function,
color: null or color,
radius: null or number
},
yerr: { same options as xerr }
}
}
Each data point array is expected to be of the type:
"x" [ x, y, xerr ]
"y" [ x, y, yerr ]
"xy" [ x, y, xerr, yerr ]
Where xerr becomes xerr_lower,xerr_upper for the asymmetric error case, and
equivalently for yerr. Eg., a datapoint for the "xy" case with symmetric
error-bars on X and asymmetric on Y would be:
[ x, y, xerr, yerr_lower, yerr_upper ]
By default no end caps are drawn. Setting upperCap and/or lowerCap to "-" will
draw a small cap perpendicular to the error bar. They can also be set to a
user-defined drawing function, with (ctx, x, y, radius) as parameters, as eg.
function drawSemiCircle( ctx, x, y, radius ) {
ctx.beginPath();
ctx.arc( x, y, radius, 0, Math.PI, false );
ctx.moveTo( x - radius, y );
ctx.lineTo( x + radius, y );
ctx.stroke();
}
Color and radius both default to the same ones of the points series if not
set. The independent radius parameter on xerr/yerr is useful for the case when
we may want to add error-bars to a line, without showing the interconnecting
points (with radius: 0), and still showing end caps on the error-bars.
shadowSize and lineWidth are derived as well from the points series.
*/
(function ($) {
var options = {
series: {
points: {
errorbars: null, //should be 'x', 'y' or 'xy'
xerr: {err: 'x', show: null, asymmetric: null, upperCap: null, lowerCap: null, color: null, radius: null},
yerr: {err: 'y', show: null, asymmetric: null, upperCap: null, lowerCap: null, color: null, radius: null}
}
}
};
function processRawData(plot, series, data, datapoints) {
if (!series.points.errorbars)
return;
// x,y values
var format = [
{x: true, number: true, required: true},
{y: true, number: true, required: true}
];
var errors = series.points.errorbars;
// error bars - first X then Y
if (errors == 'x' || errors == 'xy') {
// lower / upper error
if (series.points.xerr.asymmetric) {
format.push({x: true, number: true, required: true});
format.push({x: true, number: true, required: true});
} else
format.push({x: true, number: true, required: true});
}
if (errors == 'y' || errors == 'xy') {
// lower / upper error
if (series.points.yerr.asymmetric) {
format.push({y: true, number: true, required: true});
format.push({y: true, number: true, required: true});
} else
format.push({y: true, number: true, required: true});
}
datapoints.format = format;
}
function parseErrors(series, i) {
var points = series.datapoints.points;
// read errors from points array
var exl = null,
exu = null,
eyl = null,
eyu = null;
var xerr = series.points.xerr,
yerr = series.points.yerr;
var eb = series.points.errorbars;
// error bars - first X
if (eb == 'x' || eb == 'xy') {
if (xerr.asymmetric) {
exl = points[i + 2];
exu = points[i + 3];
if (eb == 'xy')
if (yerr.asymmetric) {
eyl = points[i + 4];
eyu = points[i + 5];
} else
eyl = points[i + 4];
} else {
exl = points[i + 2];
if (eb == 'xy')
if (yerr.asymmetric) {
eyl = points[i + 3];
eyu = points[i + 4];
} else
eyl = points[i + 3];
}
// only Y
} else if (eb == 'y')
if (yerr.asymmetric) {
eyl = points[i + 2];
eyu = points[i + 3];
} else
eyl = points[i + 2];
// symmetric errors?
if (exu == null)
exu = exl;
if (eyu == null)
eyu = eyl;
var errRanges = [exl, exu, eyl, eyu];
// nullify if not showing
if (!xerr.show) {
errRanges[0] = null;
errRanges[1] = null;
}
if (!yerr.show) {
errRanges[2] = null;
errRanges[3] = null;
}
return errRanges;
}
function drawSeriesErrors(plot, ctx, s) {
var points = s.datapoints.points,
ps = s.datapoints.pointsize,
ax = [s.xaxis, s.yaxis],
radius = s.points.radius,
err = [s.points.xerr, s.points.yerr];
//sanity check, in case some inverted axis hack is applied to flot
var invertX = false;
if (ax[0].p2c(ax[0].max) < ax[0].p2c(ax[0].min)) {
invertX = true;
var tmp = err[0].lowerCap;
err[0].lowerCap = err[0].upperCap;
err[0].upperCap = tmp;
}
var invertY = false;
if (ax[1].p2c(ax[1].min) < ax[1].p2c(ax[1].max)) {
invertY = true;
var tmp = err[1].lowerCap;
err[1].lowerCap = err[1].upperCap;
err[1].upperCap = tmp;
}
for (var i = 0; i < s.datapoints.points.length; i += ps) {
//parse
var errRanges = parseErrors(s, i);
//cycle xerr & yerr
for (var e = 0; e < err.length; e++) {
var minmax = [ax[e].min, ax[e].max];
//draw this error?
if (errRanges[e * err.length]) {
//data coordinates
var x = points[i],
y = points[i + 1];
//errorbar ranges
var upper = [x, y][e] + errRanges[e * err.length + 1],
lower = [x, y][e] - errRanges[e * err.length];
//points outside of the canvas
if (err[e].err == 'x')
if (y > ax[1].max || y < ax[1].min || upper < ax[0].min || lower > ax[0].max)
continue;
if (err[e].err == 'y')
if (x > ax[0].max || x < ax[0].min || upper < ax[1].min || lower > ax[1].max)
continue;
// prevent errorbars getting out of the canvas
var drawUpper = true,
drawLower = true;
if (upper > minmax[1]) {
drawUpper = false;
upper = minmax[1];
}
if (lower < minmax[0]) {
drawLower = false;
lower = minmax[0];
}
//sanity check, in case some inverted axis hack is applied to flot
if ((err[e].err == 'x' && invertX) || (err[e].err == 'y' && invertY)) {
//swap coordinates
var tmp = lower;
lower = upper;
upper = tmp;
tmp = drawLower;
drawLower = drawUpper;
drawUpper = tmp;
tmp = minmax[0];
minmax[0] = minmax[1];
minmax[1] = tmp;
}
// convert to pixels
x = ax[0].p2c(x),
y = ax[1].p2c(y),
upper = ax[e].p2c(upper);
lower = ax[e].p2c(lower);
minmax[0] = ax[e].p2c(minmax[0]);
minmax[1] = ax[e].p2c(minmax[1]);
//same style as points by default
var lw = err[e].lineWidth ? err[e].lineWidth : s.points.lineWidth,
sw = s.points.shadowSize != null ? s.points.shadowSize : s.shadowSize;
//shadow as for points
if (lw > 0 && sw > 0) {
var w = sw / 2;
ctx.lineWidth = w;
ctx.strokeStyle = "rgba(0,0,0,0.1)";
drawError(ctx, err[e], x, y, upper, lower, drawUpper, drawLower, radius, w + w / 2, minmax);
ctx.strokeStyle = "rgba(0,0,0,0.2)";
drawError(ctx, err[e], x, y, upper, lower, drawUpper, drawLower, radius, w / 2, minmax);
}
ctx.strokeStyle = err[e].color ? err[e].color : s.color;
ctx.lineWidth = lw;
//draw it
drawError(ctx, err[e], x, y, upper, lower, drawUpper, drawLower, radius, 0, minmax);
}
}
}
}
function drawError(ctx, err, x, y, upper, lower, drawUpper, drawLower, radius, offset, minmax) {
//shadow offset
y += offset;
upper += offset;
lower += offset;
// error bar - avoid plotting over circles
if (err.err == 'x') {
if (upper > x + radius)
drawPath(ctx, [[upper, y], [Math.max(x + radius, minmax[0]), y]]);
else
drawUpper = false;
if (lower < x - radius)
drawPath(ctx, [[Math.min(x - radius, minmax[1]), y], [lower, y]]);
else
drawLower = false;
} else {
if (upper < y - radius)
drawPath(ctx, [[x, upper], [x, Math.min(y - radius, minmax[0])]]);
else
drawUpper = false;
if (lower > y + radius)
drawPath(ctx, [[x, Math.max(y + radius, minmax[1])], [x, lower]]);
else
drawLower = false;
}
//internal radius value in errorbar, allows to plot radius 0 points and still keep proper sized caps
//this is a way to get errorbars on lines without visible connecting dots
radius = err.radius != null ? err.radius : radius;
// upper cap
if (drawUpper) {
if (err.upperCap == '-') {
if (err.err == 'x')
drawPath(ctx, [[upper, y - radius], [upper, y + radius]]);
else
drawPath(ctx, [[x - radius, upper], [x + radius, upper]]);
} else if ($.isFunction(err.upperCap)) {
if (err.err == 'x')
err.upperCap(ctx, upper, y, radius);
else
err.upperCap(ctx, x, upper, radius);
}
}
// lower cap
if (drawLower) {
if (err.lowerCap == '-') {
if (err.err == 'x')
drawPath(ctx, [[lower, y - radius], [lower, y + radius]]);
else
drawPath(ctx, [[x - radius, lower], [x + radius, lower]]);
} else if ($.isFunction(err.lowerCap)) {
if (err.err == 'x')
err.lowerCap(ctx, lower, y, radius);
else
err.lowerCap(ctx, x, lower, radius);
}
}
}
function drawPath(ctx, pts) {
ctx.beginPath();
ctx.moveTo(pts[0][0], pts[0][1]);
for (var p = 1; p < pts.length; p++)
ctx.lineTo(pts[p][0], pts[p][1]);
ctx.stroke();
}
function draw(plot, ctx) {
var plotOffset = plot.getPlotOffset();
ctx.save();
ctx.translate(plotOffset.left, plotOffset.top);
$.each(plot.getData(), function (i, s) {
if (s.points.errorbars && (s.points.xerr.show || s.points.yerr.show))
drawSeriesErrors(plot, ctx, s);
});
ctx.restore();
}
function init(plot) {
plot.hooks.processRawData.push(processRawData);
plot.hooks.draw.push(draw);
}
$.plot.plugins.push({
init: init,
options: options,
name: 'errorbars',
version: '1.0'
});
})(jQuery);
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