使用 JavaScript 和/或 D3.js 在对象数组中获取给定键的所有值

Getting all the values for a given key, in an array of objects, using JavaScript and/or D3.js

提问by user3226861

I'm building a dashboard that uses D3.js for charts. I have a large array of objects. Each object has 32 key value pairs, with the same keys. Doesn't anyone know a good way to get all the values for a given key?

我正在构建一个使用 D3.js 作为图表的仪表板。我有大量的对象。每个对象有 32 个键值对，具有相同的键。没有人知道获取给定键的所有值的好方法吗？

EDIT: As soon as I asked the question a simple function came to me. Also thought maybe a function already existed that I wasn't finding.

编辑：我一问这个问题，一个简单的功能就来找我了。还认为可能已经存在一个我没有找到的功能。

function getValues(data, key){
  var values = [];

  data.forEach(function(d){
    var v = d[key];

    if(!d3.set(values).has(v)){
      values.push(v);
    }
  })

  return values;
}

采纳答案by Daniel F

I have to create a lot of dashboards using D3 as well. Another option for you which I utilize a lot is underscore.js. It saves me time, and for my needs helps condense code. There is a function called 'pluck' in underscore, which does exactly what you asked for. For an array of objects, you can declare a key and it will return all values.

我还必须使用 D3 创建很多仪表板。我经常使用的另一个选择是 underscore.js。它节省了我的时间，并且根据我的需要帮助压缩代码。下划线中有一个名为“pluck”的函数，它完全符合您的要求。对于对象数组，您可以声明一个键，它将返回所有值。

Example:

例子：

var data = [{name: 'dan', value: 40}, {name: 'ryan', value: 50}];
var getKeys = _.pluck(data, 'name');
=> ["dan", "ryan"]

http://underscorejs.org/#pluck

http://underscorejs.org/#pluck

回答by Joshua Romero

If you're already using d3, take a look at Mike Bostock's "Underscore Equivalents" gist: https://gist.github.com/mbostock/3934356

如果您已经在使用 d3，请查看 Mike Bostock 的“Underscore Equivalents”要点：https: //gist.github.com/mbostock/3934356

So

所以

data.map(function(d) { return d[key]; });

will get you all the values. If you only want unique values, use

会给你所有的价值。如果您只想要唯一值，请使用

d3.set(data.map(function(d) { return d[key]; })).values());

回答by Learning stats by example

Use d3.keys():

使用d3.keys()：

d3.keys(data).filter(function(key) { return key })

回答by Royi Namir

Assuming you mean valuesas simple primitive values -

假设你的意思values是简单的原始值 -

You can use this altered code of myne (which was originally used to flatten object actually) - to find all the values for specific key (recursive) :

您可以使用 myne 的这个修改过的代码（它最初实际上是用来扁平化对象的） - 找到特定键（递归）的所有值：

Example : for a verycomplex object , let's find all the values for a given key named "a"

示例：对于一个非常复杂的对象，让我们找到名为“a”的给定键的所有值

var data ={a:5,g: [{"a":1,"b":[4,5,6,{a:55},[33, new Date()]]},{"c":2},{"a":3}]};

var g=[];

if (!Object.keys) { //not all browsers support it
    Object.keys = function (obj) {
        var keys = [],
            k;
        for (k in obj) {
            if (Object.prototype.hasOwnProperty.call(obj, k)) {
                keys.push(k);
            }
        }
        return keys;
    };
}

function actualType(o)
{
  return Object.prototype.toString.apply(o);
}

var arr=actualType([]);
var obj=actualType({});

function work(a, val)
{
    if (actualType(a) == obj || actualType(a) == arr)
    {
        for (var j = 0; j < Object.keys(a).length; j++)
        {
            if (Object.keys(a)[j] == val) g.push(a[Object.keys(a)[j]]);
            else
                work(a[Object.keys(a)[j]], val);
        }
    }
}

work(data,'a') //'a' is the value we're searching
console.log(g) //[5, 1, 55, 3] 

http://jsbin.com/yofafove/1/edit

http://jsbin.com/yoffove/1/edit