js 算数组平均值最大值最小值偏差标准差中位数数组从小打大排序上四分位数下四分位数

Posted 2020-12-02 livalon

要算的数组命名为data

var sum = function(x,y){ return x+y;};　　//求和函数
var square = function(x){ return x*x;};　　//数组中每个元素求它的平方

var data = [1,1,3,5,5];　　//
var mean = data.reduce(sum)/data.length;
var deviations = data.map(function(x){return x-mean;});
var stddev = Math.sqrt(deviations.map(square).reduce(sum)/(data.length-1));

var max = Math.max.apply(null,data)
var min = Math.min.apply(null,data)

var compare = function (x, y) {//比较函数
    if (x < y) {
        return -1;
    } else if (x > y) {
        return 1;
    } else {
        return 0;
    }
};
var mid; //中位数
data.sort(compare); //数组排序
if (data.length%2==0){
    mid = (data[data.length/2]+data[data.length/2+1])/2
}
if (data.length%2!=0){
    mid = data[(data.length+1)/2]
}

console.log("平均值："+mean);
console.log("偏差："+deviations);
console.log("标准差："+stddev); 
console.log("最大值："+max); 
console.log("最小值："+min);
console.log("中位数:"+mid);
console.log("上四分位数:"+data[data.length/4]);
console.log("下四分位数:"+data[data.length/4*3]);