JavaScript中数组内的平均值

Question

JSON：

[{"id":"1","user":"001","answer":"1,1,3,2,2,1,3,2"},
{"id":"2","user":"002","answer":"2,3,3,2,1,1,3,2"},
{"id":"3","user":"003","answer":"3,5,3,5,3,1,3,2"}]

JavaScript：

jQuery.ajax({
    url: "file.json",
    type: "POST",
    dataType: "json",
    async: false,
    success: function (data) {
    var arr = [];
    for (i = 0; i < data.length; i++) { 
        arr.push(data[i].answer);
    }
    console.log(arr);
});

我要做的是从3个answer得到每个值的平均值，以防万一将得到这8个平均值：

2,3,3,3,2,1,3,2

Answer 1

 const arrAvg = arr => arr.reduce((a,b) => a + b, 0) / arr.length; console.log(arrAvg([1,2,3,4,5])); 

Answer 2

你可以使用：

• Array.prototype.map()
• Array.prototype.reduce()
• String.prototype.split()
• Arrow functions

---

工作实例：

 let data = [{"id":"1","user":"001","answer":"1,1,3,2,2,1,3,2"}, {"id":"2","user":"002","answer":"2,3,3,2,1,1,3,2"}, {"id":"3","user":"003","answer":"3,5,3,5,3,1,3,2"}]; let result = data.map(o => { /* Split the string into array using , delimiter */ let a = o["answer"].split(","); /* * Return average of array by first creating sum using .reduce() and * then dividing by number of array elements. */ return a.reduce((a,c) => (Number(c) + a), 0) / a.length; }); console.log(result); 

Answer 3

从answer创建一个新数组，然后将所有值相加并除以其大小

 var res = [{ "id": "1", "user": "001", "answer": "1,1,3,2,2,1,3,2" }, { "id": "2", "user": "002", "answer": "2,3,3,2,1,1,3,2" }, { "id": "3", "user": "003", "answer": "3,5,3,5,3,1,3,2" } ]; res.forEach(function(item) { //creating array from the string var imtArray = item.answer.split(','); //summing the element var avg = imtArray.reduce(function(p, q) { // converting string to number return +p + +q }) console.log(avg / imtArray.length) }) 

Answer 4

你得到了answer ，但现在你需要用逗号分割它并将其解析为一个数字。 这为每个answer提供了一个数组，现在您可以简单地遍历每个answer并添加数字然后除以它们的计数（即数组长度）来计算平均值。

注意：答案中的值是字符串，因此请确保在将它们添加到一起之前将它们转换为数字，否则您将它们作为字符一起添加。

 var data = [{"id":"1","user":"001","answer":"1,1,3,2,2,1,3,2"}, {"id":"2","user":"002","answer":"2,3,3,2,1,1,3,2"}, {"id":"3","user":"003","answer":"3,5,3,5,3,1,3,2"}] var arr = []; for (var i = 0; i < data.length; i++) { var d = data[i].answer.split(","); var sum = 0; for (var j = 0; j < d.length; j++) { sum += parseInt(d[j]); } arr.push(sum / d.length); } console.log(arr); 

这似乎从你的意见是，除了在三个的平均值的answer S，你真正想要的每个值从三个平均answer秒。 与上面的代码类似，您只需要做一点改动。 您必须先迭代并添加每个answer的值，然后再次迭代并计算平均值：

 var data = [{"id":"1","user":"001","answer":"1,1,3,2,2,1,3,2"}, {"id":"2","user":"002","answer":"2,3,3,2,1,1,3,2"}, {"id":"3","user":"003","answer":"3,5,3,5,3,1,3,2"}] var arr = []; for (var i = 0; i < data.length; i++) { var d = data[i].answer.split(","); for (var j = 0; j < d.length; j++) { d[j] = parseInt(d[j]); } if (arr.length == 0) arr = d; else { for (var j = 0; j < d.length; j++) { arr[j] += d[j]; } } } for (var i = 0; i < arr.length; i++) { arr[i] = arr[i] / data.length; } console.log(arr); 

注意：这假定每个answer具有完全相同的值。