基于JavaScript伪随机正态分布代码实例

时间：2021-05-25

这篇文章主要介绍了基于JavaScript伪随机正态分布代码实例,文中通过示例代码介绍的非常详细，对大家的学习或者工作具有一定的参考学习价值,需要的朋友可以参考下

在游戏开发中经常遇到随机奖励的情况，一般会采取先生成数组，再一个一个取的方式发随机奖励。

下面是js测试正态分布代码：

<!DOCTYPE html><html lang="en"><head> <meta charset="UTF-8"> <title></title></head><body><canvas id="myCanvas" width="800" height="400" style="border:1px solid #c3c3c3;"> Your browser does not support the canvas element.</canvas><canvas id="myCanvas2" width="800" height="400" style="border:1px solid #c3c3c3;"> Your browser does not support the canvas element.</canvas><textarea id="text" cols="200" rows="5000"></textarea><script type="text/javascript"> var timesArr = []; var timesArrObj = {}; window.onload = function () {// for (var meter = 0; meter < 800; meter++) {// var times = getNumberInNormalDistribution(20, 7);// addPoint(times, meter);// timesArr.push(Math.floor(times));// }// drawGreenTab(timesArr,1); // drawLine(0, 380, 800, 380); drawResult(1); drawResult(2); drawResult(0); drawGreenTab(timesArrObj[1], 1); drawGreenTab(timesArrObj[2], 2); drawGreenTab(timesArrObj[0], 0); } //制作绿色柱状图表 function drawGreenTab(timesArr, color) { var timesTypes = {}; for (var i in timesArr) { var times = timesArr[i]; if (timesTypes[times] == null) { timesTypes[times] = 0; } else { timesTypes[times] = timesTypes[times] + 1; } } for (var i in timesTypes) { drawRect(i, timesTypes[i], 4, color); } } //画圆点 function addPoint(y, x, color) { y = 400 - y; var c = document.getElementById("myCanvas"); var cxt = c.getContext("2d"); if (color == null) { cxt.fillStyle = "#FF0000"; } else { cxt.fillStyle = color; } cxt.beginPath(); cxt.arc(x, y, 2, 0, Math.PI * 2, true); cxt.closePath(); cxt.fill(); } var meter = 0; //划线 function drawLine(beginx, beginy, endx, endy) { var c = document.getElementById("myCanvas"); var cxt = c.getContext("2d"); cxt.moveTo(beginx, beginy); cxt.lineTo(endx, endy); cxt.stroke(); } //模拟正态分布取值 function getNumberInNormalDistribution(mean, std_dev) { return mean + (uniform2NormalDistribution() * std_dev); } //模拟正态分布偏差 function uniform2NormalDistribution() { var sum = 0.0; for (var i = 0; i < 12; i++) { sum = sum + Math.random(); } return sum - 6; } //画一个长方形 function drawRect(x, y, width, index) { var color = "#FF0000"; if (index == 1) { color = "#00FF00"; } else if (index == 2) { color = "#0000FF"; } var c = document.getElementById("myCanvas2"); var cxt = c.getContext("2d"); cxt.fillStyle = color; cxt.fillRect(x * width + index * 200, 400 - y, width - 2, y); } //画出生成的图像 function drawResult(index) { var color = "#FF0000"; if (index % 3 == 1) { color = "#00FF00"; } else if (index % 3 == 2) { color = "#0000FF"; } var result = generateList(); var resultStr = "";// for (var i in result) {// resultStr = resultStr + result[i] + "\n";// } //document.getElementById("text").value = resultStr; var resulttimes = {}; for (var i in result) { if (resulttimes[result[i]] == null) { resulttimes[result[i]] = 1; } else { resulttimes[result[i]] = resulttimes[result[i]] + 1; } } for (var i in resulttimes) { resultStr = resultStr + resulttimes[i] + "\n"; } document.getElementById("text").value = resultStr; var timeslist = []; var times = 1; for (var i in result) { if (result[i] == index) { addPoint(times, i / 5, color); if (timesArrObj[index] == null) { timesArrObj[index] = []; } timesArrObj[index].push(times); times = 0; } else { times++; } } } //权重数组 var wt = [105, 216, 316, 488, 1000, 2000, 3680, 5890];//,14770,71535 //生成结果数组函数，结果为权重数组的索引，从0开始 function generateList() { //生成的结果数组长度 var n = 50000; var wtp = []; var sum = 0; for (var i in wt) { sum = sum + wt[i]; } for (var i in wt) { wtp.push(wt[i] / sum); } var result = []; var p = []; for (var i in wtp) { var inp = getNumberInNormalDistribution(1 / wtp[i], 1 / wtp[i] / 3); p.push(inp); } for (var i = 0; i < n; i++) { var minp = 99999999; var minj = -1; for (var j in p) { if (p[j] < minp) { minp = p[j]; minj = j; } } result.push(minj); for (var j in p) { p[j] = p[j] - minp; } p[minj] = getNumberInNormalDistribution(1 / wtp[minj], 1 / wtp[minj] / 3); } return result; }</script></body></html>

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