HTML Canvas
HTML Canvas 非常適合散點圖
HTML Canvas 非常適合折線圖
HTML Canvas 非常適合結合散點和線條
散點圖
原始碼
const xArray = [50,60,70,80,90,100,110,120,130,140,150];
const yArray = [7,8,8,9,9,9,10,11,14,14,15];
// 繪製散點圖
ctx.fillStyle = "red";
for (let i = 0; i < xArray.length-1; i++) {
let x = xArray[i]*400/150;
let y = yArray[i]*400/15;
ctx.beginPath();
ctx.ellipse(x, y, 2, 3, 0, 0, Math.PI * 2);
ctx.fill();
}
折線圖
原始碼
const xMax = canvas.height = canvas.width;
const slope = 1.2;
const intercept = 70;
// 繪製線條
ctx.beginPath();
ctx.moveTo(0, intercept);
ctx.lineTo(xMax, xMax * slope + intercept);
ctx.stroke();
組合
原始碼
let xMax = canvas.height;
let yMax = canvas.width;
let slope = 1.2;
let intercept = 70;
const xArray = [50,60,70,80,90,100,110,120,130,140,150];
const yArray = [7,8,8,9,9,9,10,11,14,14,15];
// 繪製散點圖
ctx.fillStyle = "red";
for (let i = 0; i < xArray.length-1; i++) {
let x = xArray[i] * xMax/150;
let y = yArray[i] * yMax/15;
ctx.beginPath();
ctx.ellipse(x, y, 2, 3, 0, 0, Math.PI * 2);
ctx.fill();
}
// 繪製線條
ctx.beginPath();
ctx.moveTo(0, intercept);
ctx.lineTo(xMax, xMax * slope + intercept);
ctx.stroke();
擁有一個繪圖物件對於學習人工智慧很有幫助
- 讓 AI 更加有趣
- 讓 AI 更加直觀
- 讓 AI 更加易於理解
建立繪圖物件
示例
function XYPlotter(id) {
this.canvas = document.getElementById(id);
this.ctx = this.canvas.getContext("2d");
this.xMin = 0;
this.yMin = 0;
this.xMax = this.canvas.width;
this.yMax = this.canvas.height;
.
.
新增一個繪製直線的方法
示例
this.plotLine = function(x0, y0, x, y, color) {
this.ctx.moveTo(x0, y0);
this.ctx.lineTo(x, y);
this.ctx.strokeStyle = color;
this.ctx.stroke();
}
新增一個轉換 XY 值的方法
示例
this.transformXY = function() {
this.ctx.transform(1, 0, 0, -1, 0, this.canvas.height)
}
新增一個繪製點的方法
示例
this.plotPoints = function(n, xArr, yArr, color, radius = 3) {
for (let i = 0; i < n; i++) {
this.ctx.fillStyle = color;
this.ctx.beginPath();
this.ctx.ellipse(xArr[i], yArr[i], radius, radius, 0, 0, Math.PI * 2);
this.ctx.fill();
}
}
繪製一些隨機點
示例
// 建立一個繪圖器
let myPlotter = new XYPlotter("myCanvas");
// 建立隨機 XY 點
numPoints = 500;
const xPoints = Array(numPoints).fill(0).map(function(){return Math.random() * myPlotter.xMax});
const yPoints = Array(numPoints).fill(0).map(function(){return Math.random() * myPlotter.yMax});
// 繪製這些點
myPlotter.plotPoints(numPoints, xPoints, yPoints, "blue");
將程式碼放入庫
原始碼
function XYPlotter(id) {
this.canvas = document.getElementById(id);
this.ctx = this.canvas.getContext("2d");
this.xMin = 0;
this.yMin = 0;
this.xMax = this.canvas.width;
this.yMax = this.canvas.height;
// Plot Line Function
this.plotLine = function(x0, y0, x, y, color) {
this.ctx.moveTo(x0, y0);
this.ctx.lineTo(x, y);
this.ctx.strokeStyle = color;
this.ctx.stroke();
}
// Transform XY Function
this.transformXY = function() {
this.ctx.transform(1, 0, 0, -1, 0, this.canvas.height)
}
// Pot Points Function
this.plotPoints = function(n, xArr, yArr, color, radius = 3) {
for (let i = 0; i < n; i++) {
this.ctx.fillStyle = color;
this.ctx.beginPath();
this.ctx.ellipse(xArr[i], yArr[i], radius, radius, 0, 0, Math.PI * 2);
this.ctx.fill();
}
}
} // 結束 Plotter 物件
將其儲存在一個檔案（例如“myplotlib.js”）
在你的 HTML 頁面中使用它
現在你可以將繪圖物件新增到你的 HTML 頁面中
