在对象数组中查找多个值的d3范围

Question

我的数据数组:

var data = [{glazed: 3.50, jelly: 4.50, powdered: 1.00, sprinkles: 3.50, age: 21, responses: 2,name:"test"},
    {glazed: 2.83, jelly: 3.50, powdered: 1.83, sprinkles: 4.50, age: 22, responses: 6,name:"test"},
    {glazed: 3.25, jelly: 4.75, powdered: 2.25, sprinkles: 3.50, age: 23, responses: 4,name:"test"},
    {glazed: 1.50, jelly: 4.00, powdered: 2.50, sprinkles: 4.00, age: 25, responses: 2,name:"test"}];

如果我想找到玻璃或果冻或粉末或洒水的范围用于缩放,我会使用如下代码..

var x = d3.scale.linear()
                .domain(d3.extent(data, function (d) {
                    return d.glazed;//or jelly etc..
                }))
                .range([0, width]);

我需要做些什么才能获得釉面,果冻,粉末和洒水中所有值的范围,而不是所有不是年龄,响应和名称的值.

这是因为json文件是动态创建的,所以我不知道除了年龄,响应和名称之外的键值.

所以,我的要求是它应该给我最小1.5(从上釉)和最大4.75(从果冻)

任何帮助都是真诚的感谢..

谢谢

Answer 1

var x = d3.scale.linear()
   .domain(d3.extent(data.map(function (item) {
        return (item.glazed);
   })))
   .range([0, width]);

map() 回报 [3.5, 2.83, 3.25, 1.5]

extent() 回报 [1.5, 3.5]

如果你需要所有属性的绝对最小值和最大值data,你应该连接数组:

var x = d3.scale.linear()
   .domain(d3.extent(
    [].concat(data.map(function (item) {
        return (item.glazed);
    }), data.map(function (item) {
        return (item.jelly);
    }), data.map(function (item) {
        return (item.powdered);
    }), data.map(function (item) {
        return (item.sprinkles);
    }))))
   .range([0, width]);

最后,如果您有宝贵的属性列表,则应更换[].concat(...)通过匿名函数表达式,并立即调用它是这样的:function(array, names){...}(data, temp).您应该知道,在JavaScript array.property和array["property"]- 是相同的调用.

var temp = ["glazed", "jelly", "powdered", "sprinkles"];
var width = 1000;
var data = [{glazed: 3.50, jelly: 4.50, powdered: 1.00, sprinkles: 3.50, age: 21, responses: 2,name:"test"},
    {glazed: 2.83, jelly: 3.50, powdered: 1.83, sprinkles: 4.50, age: 22, responses: 6,name:"test"},
    {glazed: 3.25, jelly: 4.75, powdered: 2.25, sprinkles: 3.50, age: 23, responses: 4,name:"test"},
    {glazed: 1.50, jelly: 4.00, powdered: 2.50, sprinkles: 4.00, age: 25, responses: 2,name:"test"}];


var x = d3.scale.linear()
   .domain(d3.extent(
       function(array, names){
          var res = [];
          array.forEach(function(item){
             names.forEach(function(name){
                res = res.concat(item[name]);
             });
          });
          return(res);
       }(data, temp)
    ))
   .range([0, width]);

演示:http://jsfiddle.net/v5qzuuhj/