D3 js从包含特定键值的对象获取d3.max [英] D3 js get a d3.max from an object that contains a specific key value

问题描述

我有以下数据集，并尝试获取d3.max来指定比例域，但仅从具有key enabled = true的对象中获取d3.max值.如何实现?

I have the following dataset and am trying to get the d3.max to specify a domain for a scale, but want the d3.max value only from objects that have the key enabled=true. How can this be achieved?

[{
    "key": "name1",
    "enabled": "true",
    "values": [{
        "date": "2016-09-13T02:11:44Z",
        "value": "100",
    }, {
        "date": "2016-09-13T02:11:44Z",
        "value": "200",
    }]
}, {
    "key": "name2",
    "enabled": "false",
    "values": [{
        "date": "2016-09-13T02:11:44Z",
        "value": "400",
    }, {
        "date": "2016-09-13T02:11:44Z",
        "value": "500",
    }]
}]

我认为我应该以某种方式使用钥匙，但是还没有做到.有人可以指出我正确的方向吗?这就是我到目前为止所拥有的...

I think I am supposed to use a key somehow, but haven't been able to do it. Can someone point me to the right direction? This is what I have so far...

d3.max(dataset, function(c) { return d3.max(c.values, function(d) { return d.value; }); })

推荐答案

如果您需要一行:

var max = d3.max(data.filter(d => d.enabled === "true"), e => d3.max(e.values, f => f.value));

或者，没有箭头功能:

var max = d3.max(data.filter(function(d) {
    return d.enabled === "true";
}), function(e) {
    return d3.max(e.values, function(f) {
        return f.value;
    });
});

这是一个演示:

var data = [{
  "key": "name1",
  "enabled": "true",
  "values": [{
    "date": "2016-09-13T02:11:44Z",
    "value": "100",
  }, {
    "date": "2016-09-13T02:11:44Z",
    "value": "200",
  }]
}, {
  "key": "name2",
  "enabled": "false",
  "values": [{
    "date": "2016-09-13T02:11:44Z",
    "value": "400",
  }, {
    "date": "2016-09-13T02:11:44Z",
    "value": "500",
  }]
}];

var max = d3.max(data.filter(d => d.enabled === "true"), e => d3.max(e.values, f => f.value));

console.log(max);

<script src="https://d3js.org/d3.v4.min.js"></script>

它使用enabled: "true"接受多个对象，请检查第二个演示，我在您的数据数组中放置了另一个对象:

It accepts more than one object with enabled: "true", check this second demo, I put another object in your data array:

var data = [{
  "key": "name1",
  "enabled": "true",
  "values": [{
    "date": "2016-09-13T02:11:44Z",
    "value": "100",
  }, {
    "date": "2016-09-13T02:11:44Z",
    "value": "200",
  }]
}, {
  "key": "name2",
  "enabled": "false",
  "values": [{
    "date": "2016-09-13T02:11:44Z",
    "value": "400",
  }, {
    "date": "2016-09-13T02:11:44Z",
    "value": "500",
  }]
},{
  "key": "name1",
  "enabled": "true",
  "values": [{
    "date": "2016-09-13T02:11:44Z",
    "value": "800",
  }, {
    "date": "2016-09-13T02:11:44Z",
    "value": "200",
  }]
}];

var max = d3.max(data.filter(d => d.enabled === "true"), e => d3.max(e.values, f => f.value));

console.log(max);

<script src="https://d3js.org/d3.v4.min.js"></script>

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