平均在JavaScript

Question

然后我需要一个得到平均高点的函数。下面是我做的：

    function getAverageHeight() {
        let total_height = 0;
        let average_height = statues.length;

        if (statues.length > 0) {
            for (let i = 0; i < statues.length; i++) {
                let statue = statues[i];

                total_height += isNaN(statues.height) ? 0 : statue.height;
            }
        average_height = (total_height / statues.length).toFixed(2);
         }
       return average_height;
       } 

但当我测试它时，我得到的回答不是平均值。我做错了什么？有人能提供线索吗？

Answer 1

创建一个函数，该函数在每次调用数组时累加数组中的对象。

创建一个单独的平均值函数，如果height是一个数字，该函数将获取该累计数组并返回height的平均结果

let statues = [];
function createStatue(name, city, height) {
  return statues = [...statues, {
    name,
    city,
    height
  }]
}
// call functions to populate array
createStatue("Statue of Liberty", "New York", 46);
createStatue("Christ the Redeemer", "Rio de Janeiro", 30);
createStatue("David", "Florence", 5.17);
createStatue("Little Mermaid", "Copenhagen", 1.25);
createStatue("Winged Victory", "Paris", 2.44);
createStatue("Venus de Milo", "Paris", 2);


function getAverageHeight() {
  const total = statues.reduce((acc, x) => {
    if (!isNaN(x.height)) {
      acc.counter += 1
      acc.sum += x.height;
    }
    return acc;
  }, {
    sum: 0,
    counter: 0
  })
  return (total.sum / total.counter).toFixed(2)

}

console.log(getAverageHeight())

Answer 2

你想用

isNaN(statue.height)

而不是

isNaN(statues.height)

Answer 3

这里的许多解决方案都非常好，但是也有像true和"这样的带有isnan的边缘情况。首先使用parseInt更安全。这里有一个解决方案，它剔除边缘情况并返回平均值。

let statues = [];
function createStatue(name, city, heightInMeters) {
  statues.push({
    name,
    city,
    heightInMeters
  });
}

// create statues + edge cases inputs
createStatue("Number", "New York", 46);
createStatue("Decimal", "Florence", 5.17);
createStatue("String", "Florence", '123');
createStatue("True", "Boston", true);
createStatue("Empty", "New York City", '');


function getAverageHeight() {
  // Filter out bad cases here
  const filteredStatues = statues.filter((x) => {
    let num = parseInt(x.heightInMeters);
    return !isNaN(num);
  });

  const total = filteredStatues.reduce((acc, x) => {
    return acc+parseInt(x.heightInMeters);
  }, 0);
  return (total/filteredStatues.length).toFixed(2);
}

console.log(getAverageHeight());

编辑：操作系统提供了原始代码。看看它，有一些奇怪的地方。

heightInMeters: heightInMeters,
  isLongerThan: function (other_statue) {            
    return this.highInMeters > other_statue.hightInMeters;

看起来这里有几个输入错误，代码不应该运行。