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c5dcf5a20d
* Update docs on chart extensions * Working sample for derived chart types * Add derived axis example * Remove duplicated line
137 lines
2.8 KiB
HTML
137 lines
2.8 KiB
HTML
<!doctype html>
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<html>
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<head>
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<title>Logarithmic Line Chart</title>
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<script src="../../dist/chart.min.js"></script>
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<script src="../utils.js"></script>
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<style>
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canvas {
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-moz-user-select: none;
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-webkit-user-select: none;
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-ms-user-select: none;
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}
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</style>
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</head>
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<body>
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<div style="width:75%;">
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<canvas id="canvas"></canvas>
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</div>
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<script>
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var randomScalingFactor = function() {
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return Math.pow(2, Math.ceil(Math.random() * 10));
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};
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class Log2Axis extends Chart.Scale {
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constructor(cfg) {
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super(cfg);
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this._startValue = undefined;
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this._valueRange = 0;
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}
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parse(raw, index) {
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const value = Chart.registry.getScale('linear').prototype.parse.apply(this, [raw, index]);
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return isFinite(value) && value > 0 ? value : null;
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}
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determineDataLimits() {
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const {min, max} = this.getMinMax(true);
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this.min = isFinite(min) ? Math.max(0, min) : null;
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this.max = isFinite(max) ? Math.max(0, max) : null;
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}
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buildTicks() {
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const ticks = [];
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let power = Math.floor(Math.log2(this.min));
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let maxPower = Math.ceil(Math.log2(this.max));
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while (power <= maxPower) {
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ticks.push({value: Math.pow(2, power)});
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power += 1;
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}
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this.min = ticks[0].value;
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this.max = ticks[ticks.length - 1].value;
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return ticks;
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}
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/**
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* @protected
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*/
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configure() {
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const start = this.min;
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super.configure();
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this._startValue = Math.log2(start);
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this._valueRange = Math.log2(this.max) - Math.log2(start);
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}
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getPixelForValue(value) {
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if (value === undefined || value === 0) {
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value = this.min;
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}
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return this.getPixelForDecimal(value === this.min ? 0 : (Math.log2(value) - this._startValue) / this._valueRange);
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}
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getValueForPixel(pixel) {
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const decimal = this.getDecimalForPixel(pixel);
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return Math.pow(2, this._startValue + decimal * this._valueRange);
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}
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}
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Log2Axis.id = 'log2';
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Log2Axis.defaults = {};
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Chart.register(Log2Axis);
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var config = {
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type: 'line',
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data: {
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labels: ['January', 'February', 'March', 'April', 'May', 'June', 'July'],
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datasets: [{
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label: 'My First dataset',
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backgroundColor: window.chartColors.red,
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borderColor: window.chartColors.red,
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fill: false,
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data: [
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randomScalingFactor(),
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randomScalingFactor(),
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randomScalingFactor(),
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randomScalingFactor(),
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randomScalingFactor(),
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randomScalingFactor(),
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randomScalingFactor()
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],
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}]
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},
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options: {
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responsive: true,
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plugins: {
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title: {
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display: true,
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text: 'Derived Axis Type - Log2'
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}
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},
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scales: {
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x: {
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display: true,
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},
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y: {
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display: true,
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type: 'log2',
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}
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}
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}
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};
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window.onload = function() {
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var ctx = document.getElementById('canvas').getContext('2d');
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window.myLine = new Chart(ctx, config);
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};
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</script>
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</body>
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</html>
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