188 lines
6.0 KiB
HTML
188 lines
6.0 KiB
HTML
<!DOCTYPE html>
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<html>
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<head>
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<title>Tax forms: Bar chart with lines</title>
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<meta charset="UTF-8">
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<script src="taxForms.js"></script>
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</head>
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<body>
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<canvas id="chart" width="700" height="550"></canvas>
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<script>
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const canvas = document.getElementById('chart');
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const context = canvas.getContext('2d');
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/* Draw a line from (fromX, fromY) to (toX, toY) */
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function drawLine(fromX, fromY, toX, toY) {
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context.beginPath();
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context.moveTo(toX, toY);
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context.lineTo(fromX, fromY);
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context.stroke();
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}
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/* Draw a text (string) on (x, y) */
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function drawText(text, x, y) {
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context.fillStyle = 'black';
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context.fillText(text, x, y);
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}
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/* Draw a text and with a line to its right */
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function drawLineWithText(text, fromX, fromY, toX, toY) {
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drawText(text, fromX - 50, fromY + 10);
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drawLine(fromX, fromY, toX, toY);
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}
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/* Insert your code here. */
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/**
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* Draw lines on the y axis of the canvas
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*
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* @param {number} n - Number of lines to draw
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* @param {number} step - Number to add to y axis
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*/
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const drawNLines = (n, step) => {
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for (let i = 1; i <= n; i++) {
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const y = canvas.height * (n - i + 1 ) / (n+1);
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const text = step * i;
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drawLineWithText(text, 50, y, canvas.width - 100, y);
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}
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}
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/**
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* Draws a rectangle onto the canvas
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*
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* @param {number} x - x value of the upper left corner of the rectangle
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* @param {number} y - y value of the upper left corner of the rectangle
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* @param {number} width - Width of the rectangle
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* @param {number} height - Height of the rectangle (DOWNWARDS)
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* @param {string} color - Color of the rectangle
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*/
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const drawRectangle = (x, y, width, height, color='red') => {
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context.fillStyle = color;
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context.fillRect(x, y, width, height);
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}
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/**
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* Cycle a list of colors
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*
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* @generator
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*
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* @param {string[]} colors - List of colors to cycle
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* @yields {string} A color
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*/
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function* colorCycler(colors) {
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let i = 0;
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while (true) {
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yield colors[i];
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i = (i + 1) % colors.length
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}
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}
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/**
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* Draw a legend entry on the canvas
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*
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* @param {string[]} properties - An array of labels
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* @param {[string[]} colorList - An array of colors to cycle when making labels
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*/
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const drawLabels = (properties, colorList) => {
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const colors = colorCycler(colorList);
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const drawLabel = (text, color, y) => {
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drawText(text, canvas.width-45, y + 15)
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drawRectangle(canvas.width - 90, y, 40, 20, color);
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}
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const yOffset = canvas.height / 12
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for (i in properties) {
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drawLabel(properties[i], colors.next().value, yOffset+30*i);
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}
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}
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/**
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* Draw a subset of bars on the canvas
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*
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* param {{
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* x: number,
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* width: number,
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* adjustY: {val: number}=>number,
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* object: Object.<string, number>,
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* sep: number,
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* colorList: string[]
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* }} config -
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* x: x value of where to start drawing bars
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* width: Width of all the bars to draw collected
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* adjustY: A function to adjust the y value of each bar to the upper left corner
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* object: The object containing the values to draw
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* sep: The amount of pixels between each bar
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* colorList: A list of colors to cycle when creating bars
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*/
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const drawBars = ({x, width, adjustY, object, sep, colorList}) => {
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const colors = colorCycler(colorList);
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const values = Object.values(object)
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const drawBar = (value, x) => {
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const y = adjustY(value);
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const localWidth = width / (values.length) - sep;
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const localHeight = canvas.height - y;
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drawRectangle(x, y, localWidth, localHeight, colors.next().value);
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}
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for (let i=0; i<values.length; i++) {
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const xOffset = x + i * (sep + width / (values.length));
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drawBar(values[i], xOffset);
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}
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colors.return();
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}
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/**
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* Draw an array of objects as a diagram onto the canvas
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*
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* @param {Array.<Object.<string, number>>} data - An array of objects with graphable properties
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* @param {string[]} colorList - An array of colors to cycle when drawing bars
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* @param {{val: number}=>number} adjustY - A function to adjust the y value of
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* each bar to the upper left corner
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*/
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const drawColumnSet = (data, colorList, adjustY) => {
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const lineWidth = canvas.width - 150;
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const columnSetWidth = lineWidth / (2 * data.length + 1) - data.length + 1;
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const initialXOffset = 50 + columnSetWidth;
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const xOffset = 2*columnSetWidth;
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for (i in data) {
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drawBars({
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x: initialXOffset + i*xOffset,
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width: columnSetWidth,
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adjustY: adjustY,
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object: data[i],
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sep: 5,
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colorList: colorList
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});
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}
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}
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/**
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* Draw a bar chart diagram
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*
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* @param {Array.<Object.<string, number>>} data - An array of objects with graphable properties
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* @param {number} range - The upper range of the graph (the top line)
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* @param {number} step - The number to increase by for every unit on the axis
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*/
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const drawDiagram = (data, range, step) => {
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drawNLines(range/step, step);
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const colorList = ['red', 'blue'];
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drawLabels(Object.getOwnPropertyNames(data[0]), colorList);
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const adjustY = val => canvas.height * ( 1 - val / (step * (range/step + 1)));
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drawColumnSet(data, colorList, adjustY);
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}
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const taxData = taxForms;
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taxData.forEach(form => delete form.realName);
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drawDiagram(taxData, 1000000, 100000);
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</script>
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</body>
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</html>
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