我试图创建一个JavaScript函数，该函数从外部JSON中的数组中获取信息，然后获取其中一个JSON变量的最大值（或前5个值）。对于这个例子，让我们说我想得到值＆＃34; ppg＆＃34;的最大值。以下是该数组的一小部分示例：
[
{
"player" : "Andre Drummond",
"team" : "Detroit Pistons",
"ppg" : "15.4",
"rpg" : "11.6",
"apg" : "2.4",
"bpg" : "1.6",
"spg" : "0.8",
"3pg" : "0.1"
},
{
"player" : "Anthony Davis",
"team" : "New Orleans Pelicans",
"ppg" : "16.4",
"rpg" : "13.6",
"apg" : "2.6",
"bpg" : "3.5",
"spg" : "1.2",
"3pg" : "0.1"
},
{
"player" : "Carmelo Anthony",
"team" : "New York Knicks",
"ppg" : "27.4",
"rpg" : "5.4",
"apg" : "4.5",
"bpg" : "1.1",
"spg" : "1.5",
"3pg" : "1.6"
}
]
通过数组获取最大值然后获取值＆＃34;播放器＆＃34;的最佳方法是什么？和＃34;团队＆＃34;从这个价值？该页面将是交互式的，因为我将有一个下拉菜单栏，允许查看者在除＃34;播放器＆＃34;之外的六个JSON值之一中进行选择。和＆＃34;团队＆＃34;。提前谢谢！
答案 0 :(得分：14)
只需在数组中循环，并随时跟踪最大值：
function getMax(arr, prop) {
var max;
for (var i=0 ; i<arr.length ; i++) {
if (!max || parseInt(arr[i][prop]) > parseInt(max[prop]))
max = arr[i];
}
return max;
}
用法如下：
var maxPpg = getMax(arr, "ppg");
console.log(maxPpg.player + " - " + maxPpg.team);
修改
您还可以使用Javascript "sort"方法获取前n个值：
function getTopN(arr, prop, n) {
// clone before sorting, to preserve the original array
var clone = arr.slice(0);
// sort descending
clone.sort(function(x, y) {
if (x[prop] == y[prop]) return 0;
else if (parseInt(x[prop]) < parseInt(y[prop])) return 1;
else return -1;
});
return clone.slice(0, n || 1);
}
用法：
var topScorers = getTopN(arr, "ppg", 2);
topScorers.forEach(function(item, index) {
console.log("#" + (index+1) + ": " + item.player);
});
答案 1 :(得分：2)
我发现以下方法非常简洁：
var arr =[
{
"player" : "Andre Drummond",
"team" : "Detroit Pistons",
"ppg" : "15.4",
"rpg" : "11.6",
"apg" : "2.4",
"bpg" : "1.6",
"spg" : "0.8",
"3pg" : "0.1"
},
{
"player" : "Anthony Davis",
"team" : "New Orleans Pelicans",
"ppg" : "16.4",
"rpg" : "13.6",
"apg" : "2.6",
"bpg" : "3.5",
"spg" : "1.2",
"3pg" : "0.1"
},
{
"player" : "Carmelo Anthony",
"team" : "New York Knicks",
"ppg" : "27.4",
"rpg" : "5.4",
"apg" : "4.5",
"bpg" : "1.1",
"spg" : "1.5",
"3pg" : "1.6"
}
]
console.log(
arr.sort(
function(a, b) {
return parseFloat(b['ppg']) - parseFloat(a['ppg']);
}
)[0]['player']
);
首先我对数组进行降序排序，然后选择包含最大值的第一个元素。在代码中，我发现播放器的最大值 ppg 。希望这有帮助！
答案 2 :(得分：2)
function getMaxOfJson(jsonalreadyparsed, property) {
var max = null;
for (var i=0 ; i<jsonalreadyparsed.length ; i++) {
if(max == null){
max = jsonalreadyparsed[i][property];
} else {
if (parseFloat(jsonalreadyparsed[i][property]) > max){
max = jsonalreadyparsed[i][property];
}
}
}
return max;
}
这适合我。
答案 3 :(得分：1)
这应该有效：
var highestValue = 0; //keep track of highest value
//loop through array of objects
for (var i=0, len = ary.length; i<len; i++) {
var value = Number(ary[i]["ppg"]);
if (value > highestValue) {
highestValue = value;
}
}
答案 4 :(得分：1)
您可能会发现此sortByAttribute函数很有用。只需按字符串传递属性即可对其进行排序，并且它将返回任何具有您正在查找的特定属性的最大值的对象。它仍然会返回整个数组，只是按你指定的属性进行升序排序。
var myArr = [
{
"player" : "Andre Drummond",
"team" : "Detroit Pistons",
"ppg" : "15.4",
"rpg" : "11.6",
"apg" : "2.4",
"bpg" : "1.6",
"spg" : "0.8",
"3pg" : "0.1"
},
{
"player" : "Anthony Davis",
"team" : "New Orleans Pelicans",
"ppg" : "16.4",
"rpg" : "13.6",
"apg" : "2.6",
"bpg" : "3.5",
"spg" : "1.2",
"3pg" : "0.1"
},
{
"player" : "Carmelo Anthony",
"team" : "New York Knicks",
"ppg" : "27.4",
"rpg" : "5.4",
"apg" : "4.5",
"bpg" : "1.1",
"spg" : "1.5",
"3pg" : "1.6"
}
]
function sortByAttribue(arr, attribute) {
return arr.sort(function(a,b) {
return a[attribute] < b[attribute];
});
}
sortByAttribue(myArr, "3pg") // returns Carmelo Anthony first
sortByAttribue(myArr, "bpg") // returns Anthony Davis first
答案 5 :(得分：0)
这将允许您选择所需的统计数据以及您想要的信息。
http://jsbin.com/tudegofa/1/edit
data =＆gt;是数组
stat =＆gt;是您要按
排序的统计数据info =＆gt;是要返回的属性数组。
function getValues (data, stat, info)
{
var selectedValues = data.map(function(x) {
return parseFloat(x[stat]);
})
var i = selectedValues.indexOf(Math.max.apply(Math, selectedValues));
var result = {};
info.forEach(function(x) {
result[x] = test[i][x];
})
return result;
}
var myData = '';
$.getJSON('/url/to/grab/json', function(data) {
myData = data;
});
getValues(myData, "bpg", ["player","team"]);
//[object Object] {
// player: "Anthony Davis",
// team: "New Orleans Pelicans"
// }
答案 6 :(得分：0)
正在寻找具有特定属性'x最大值的项目的函数：
function getMax(array, propName) {
var max = 0;
var maxItem = null;
for(var i=0; i<array.length; i++) {
var item = array[i];
if(item[propName] > max) {
max = item[propName];
maxItem = item;
}
}
return maxItem;
}
用法：
$(document).ready(function() {
$('#getMaxBtn').click(function() {
var max = getMax(jsonArray, 'ppg');
alert(max.player);
});
});
答案 7 :(得分：0)
从长远来看，简单的谢谢你。
function getMaxValueByAttribute(arr, attr) {
var max = "-99999999999";
arr.forEach(function (member, index) {
// console.log(member, index);
if (member.hasOwnProperty(attr) && parseFloat(member[attr]) > parseFloat(max)) {
max = member[attr];
// console.log("Max now: " + max);
}
});
return max;
}
然后使用它：
var result = getMaxValueByAttribute(arr, "ppg");
// result = "27.4"
答案 8 :(得分：0)
您可以轻松实现 lodash 。
# you could use this in place of `m[ m == "NA" ] <- ""`
for (i in seq_len(nrow(m))) {
for (j in seq_len(ncol(m))) {
if (m[i,j] == "NA") m[i,j] == ""
}
}
var players = [{
"player": "Andre Drummond",
"team": "Detroit Pistons",
"ppg": "15.4",
"rpg": "11.6",
"apg": "2.4",
"bpg": "1.6",
"spg": "0.8",
"3pg": "0.1"
},
{
"player": "Anthony Davis",
"team": "New Orleans Pelicans",
"ppg": "16.4",
"rpg": "13.6",
"apg": "2.6",
"bpg": "3.5",
"spg": "1.2",
"3pg": "0.1"
},
{
"player": "Carmelo Anthony",
"team": "New York Knicks",
"ppg": "27.4",
"rpg": "5.4",
"apg": "4.5",
"bpg": "1.1",
"spg": "1.5",
"3pg": "1.6"
}
];
var topscorer = _
.chain(players)
.sortBy('ppg')
.reverse()
.map(function(o) {
return 'Top scorer: ' + o.player + ' - ' + o.team;
})
.head()
.value();
console.log(topscorer);
或更短：
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.core.min.js"></script>var players = [{
"player": "Andre Drummond",
"team": "Detroit Pistons",
"ppg": "15.4",
"rpg": "11.6",
"apg": "2.4",
"bpg": "1.6",
"spg": "0.8",
"3pg": "0.1"
},
{
"player": "Anthony Davis",
"team": "New Orleans Pelicans",
"ppg": "16.4",
"rpg": "13.6",
"apg": "2.6",
"bpg": "3.5",
"spg": "1.2",
"3pg": "0.1"
},
{
"player": "Carmelo Anthony",
"team": "New York Knicks",
"ppg": "27.4",
"rpg": "5.4",
"apg": "4.5",
"bpg": "1.1",
"spg": "1.5",
"3pg": "1.6"
}
];
console.log(_.maxBy(players, 'ppg').player);
答案 9 :(得分：0)
我的解决方案在这里。请记住使用==而非===来比较数字和字符串。
const getMax = (arr, prop) => {
const tmp = arr.map(x => x[prop]);
const max = Math.max(...tmp);
return arr.filter(x => x[prop] == max);
}
getMax(myArr,"bpg")
单行版本：
myArr.filter( x => x["bpg"] == Math.max(...myArr.map(x => x["bpg"])) )
答案 10 :(得分：0)
更简单：
const players =
[ { player: 'Andre Drummond', team: 'Detroit Pistons', ppg: '15.4', rpg: '11.6', apg: '2.4', bpg: '1.6', spg: '0.8', '3pg': '0.1' }
, { player: 'Anthony Davis', team: 'New Orleans Pelicans', ppg: '16.4', rpg: '13.6', apg: '2.6', bpg: '3.5', spg: '1.2', '3pg': '0.1' }
, { player: 'Carmelo Anthony', team: 'New York Knicks', ppg: '27.4', rpg: '5.4', apg: '4.5', bpg: '1.1', spg: '1.5', '3pg': '1.6' }
]
const getPlayerMax_on = cod => players.reduce((a,c)=>((+a[cod])<(+c[cod]))?c:a)
const maxOn_ppg = getPlayerMax_on('ppg')
console.log( maxOn_ppg.player, maxOn_ppg.team, maxOn_ppg.ppg )