字典数组的最小值和最大值 (JSON)

Question

我无法从数据集中获取最大值和最小值。我认为这个（// Get the largest value from Json object with Javascript 结合 Math.min.apply returns 0 for null）最接近我的需要，但是我的数据有点复杂（至少从我的“初学者的角度来看”）。

我的数据集涉及从 1995 年到 2016 年所有国家/地区的预期寿命，如下所示：

[{"country":"Abkhazia","1995":null,"1996":null,"1997":null,"1998":null,"1999":null,"2000":null,"2001":null,"2002":null,"2003":null,"2004":null,"2005":null,"2006":null,"2007":null,"2008":null,"2009":null,"2010":null},
{"country":"Afghanistan","1995":null,"1996":null,"1997":null,"1998":null,"1999":null,"2000":null,"2001":null,"2002":5.7,"2003":6.8,"2004":6.4,"2005":6.6,"2006":6.8,"2007":7.3,"2008":7.0,"2009":7.6,"2010":7.6},
{"country":"Akrotiri and Dhekelia","1995":null,"1996":null,"1997":null,"1998":null,"1999":null,"2000":null,"2001":null,"2002":null,"2003":null,"2004":null,"2005":null,"2006":null,"2007":null,"2008":null,"2009":null,"2010":null},
{"country":"Albania","1995":2.6,"1996":4.0,"1997":4.8,"1998":5.3,"1999":5.8,"2000":6.4,"2001":6.0,"2002":6.3,"2003":6.2,"2004":6.9,"2005":6.8,"2006":6.7,"2007":6.9,"2008":6.7,"2009":6.9,"2010":6.5},
etc.

我需要什么：

完整数据集的最大值和最小值。
例如，这将是：

min: 2.6
max: 7.6

我正在使用 D3 制作数据图，我想使用这些值来创建一系列颜色。

我尝试过的代码

正如介绍中所说，我认为我需要结合上面给出的两个链接，但是我无法使其工作。例如，使用第二个链接，我获得了给定国家/地区的最小值，但不是所有国家/地区的最小值。

希望有人可以帮助我！

Answer 1

您可以遍历所有国家和所有键并检查该值是否不等于null。然后获取min 和max 值。

var data = [{ "country": "Abkhazia", "1995": null, "1996": null, "1997": null, "1998": null, "1999": null, "2000": null, "2001": null, "2002": null, "2003": null, "2004": null, "2005": null, "2006": null, "2007": null, "2008": null, "2009": null, "2010": null }, { "country": "Afghanistan", "1995": null, "1996": null, "1997": null, "1998": null, "1999": null, "2000": null, "2001": null, "2002": 5.7, "2003": 6.8, "2004": 6.4, "2005": 6.6, "2006": 6.8, "2007": 7.3, "2008": 7.0, "2009": 7.6, "2010": 7.6 }, { "country": "Akrotiri and Dhekelia", "1995": null, "1996": null, "1997": null, "1998": null, "1999": null, "2000": null, "2001": null, "2002": null, "2003": null, "2004": null, "2005": null, "2006": null, "2007": null, "2008": null, "2009": null, "2010": null }, { "country": "Albania", "1995": 2.6, "1996": 4.0, "1997": 4.8, "1998": 5.3, "1999": 5.8, "2000": 6.4, "2001": 6.0, "2002": 6.3, "2003": 6.2, "2004": 6.9, "2005": 6.8, "2006": 6.7, "2007": 6.9, "2008": 6.7, "2009": 6.9, "2010": 6.5 }],
    min = Number.MAX_VALUE,
    max = -Number.MAX_VALUE;

data.forEach(function (o) {
    Object.keys(o).forEach(function (k) {                
        if (k !== 'country' && o[k] !== null) {
            min = Math.min(min, o[k]);
            max = Math.max(max, o[k]);
        }
    });
});

console.log(min, max);

Answer 2

如果你被允许使用 ES6：

const maxValue = dataset.reduce( (max, obj)  => {
    let ar = [max];
    for(const key in obj) {
        if (isNaN(Number.parseFloat(obj[key]))) continue;
        ar.push(obj[key]):
    }
    return Math.max.apply(ar, Math);
}, -1)

Answer 3

我假设您要检查数组的所有元素是否有有效数字，并获取结果数字集的最小值/最大值。这是执行此操作的代码示例。可以点击运行查看结果。

data = [{"country":"Abkhazia","1995":null,"1996":null,"1997":null,"1998":null,"1999":null,"2000":null,"2001":null,"2002":null,"2003":null,"2004":null,"2005":null,"2006":null,"2007":null,"2008":null,"2009":null,"2010":null},
{"country":"Afghanistan","1995":null,"1996":null,"1997":null,"1998":null,"1999":null,"2000":null,"2001":null,"2002":5.7,"2003":6.8,"2004":6.4,"2005":6.6,"2006":6.8,"2007":7.3,"2008":7.0,"2009":7.6,"2010":7.6},
{"country":"Akrotiri and Dhekelia","1995":null,"1996":null,"1997":null,"1998":null,"1999":null,"2000":null,"2001":null,"2002":null,"2003":null,"2004":null,"2005":null,"2006":null,"2007":null,"2008":null,"2009":null,"2010":null},
{"country":"Albania","1995":2.6,"1996":4.0,"1997":4.8,"1998":5.3,"1999":5.8,"2000":6.4,"2001":6.0,"2002":6.3,"2003":6.2,"2004":6.9,"2005":6.8,"2006":6.7,"2007":6.9,"2008":6.7,"2009":6.9,"2010":6.5}];

values = [];

for (i in data) {
  for (j in data[i]) {
    if (parseFloat(data[i][j]) > 0) {
      values.push(parseFloat(data[i][j]));
    }
  }
}

min = Math.min.apply(null, values);
max = Math.max.apply(null, values);
alert(values)
alert(min);
alert(max);