从多维数组JavaScript中提取特定值

Question

I have a multidimensional array seen below. 我在下面看到一个多维数组。 I wish extract all the ingredients values from it, and then do an action with them, like count how many of each there are. 我希望从中提取所有ingredients值，然后对它们进行操作，例如计算每种成分中有多少。

var products = [
{ name: "Sonoma", ingredients: ["artichoke", "sundried tomatoes", "mushrooms"], containsNuts: false },
{ name: "Pizza Primavera", ingredients: ["roma", "sundried tomatoes", "goats cheese", "rosemary"], containsNuts: false },
{ name: "South Of The Border", ingredients: ["black beans", "jalapenos", "mushrooms"], containsNuts: false },
{ name: "Blue Moon", ingredients: ["blue cheese", "garlic", "walnuts"], containsNuts: true },
{ name: "Taste Of Athens", ingredients: ["spinach", "kalamata olives", "sesame seeds"], containsNuts: true }
];

I have done this using a function from Underscore.js, _.flatten() , and the vanilla javascript function map() , but I had to use map() twice. 我使用_.flatten() ， _.flatten()和香草javascript函数map()来完成此操作，但是我不得不两次使用map() 。 Once for extracting all the ingredients, and then to make a hash style structure that counts up the number of times each ingredient occurs. 一次提取所有成分，然后创建一个哈希样式结构，该结构计算每种成分出现的次数。 I store these counts in a separate object, ingredientCount in this case. 我这些计数存储在一个单独的对象， ingredientCount在这种情况下。

var ingredientCount = {};
_.flatten(products.map(function(x) {
    return x.ingredients;
})).map(function(y){
    return ingredientCount[y] = (ingredientCount[y] || 0) + 1;
});

console.log(ingredientCount); will output the following list: 将输出以下列表：

{ artichoke: 1,
  'sundried tomatoes': 2,
  mushrooms: 2,
  roma: 1,
  'goats cheese': 1,
  rosemary: 1,
  'black beans': 1,
  jalapenos: 1,
  'blue cheese': 1,
  garlic: 1,
  walnuts: 1,
  spinach: 1,
  'kalamata olives': 1,
  'sesame seeds': 1 }

I have solved my problem, but I feel like there should be a cleaner, more efficient way to do this without using map() twice. 我已经解决了我的问题，但是我觉得应该有一种更干净，更有效的方法来执行此操作，而无需两次使用map() 。 Can anyone help me out? 谁能帮我吗？ I apologize in advance if this is a duplicate question. 如果这是一个重复的问题，我提前致歉。

Answer 1

This is the most elegant way I can think of in plain JavaScript, as it doesn't use any intermediary data structures (the original solution creates two arrays which are then combined into the final object). 这是我在普通JavaScript中可以想到的最优雅的方法，因为它不使用任何中间数据结构（原始解决方案创建了两个数组，然后将它们组合成最终对象）。

var counts = products.reduce(function (result, product) {
    product.ingredients.forEach(function (ingredient) {
        result[ingredient] = (result[ingredient] || 0) + 1;
    });
    return result;
}, {});

Answer 2

You could use recursion: 您可以使用递归：

 var products = [ { name: "Sonoma", ingredients: ["artichoke", "sundried tomatoes", "mushrooms"], containsNuts: false }, { name: "Pizza Primavera", ingredients: ["roma", "sundried tomatoes", "goats cheese", "rosemary"], containsNuts: false }, { name: "South Of The Border", ingredients: ["black beans", "jalapenos", "mushrooms"], containsNuts: false }, { name: "Blue Moon", ingredients: ["blue cheese", "garlic", "walnuts"], containsNuts: true }, { name: "Taste Of Athens", ingredients: ["spinach", "kalamata olives", "sesame seeds"], containsNuts: true } ]; // written by hand, with <3 function ic(p,o,i,b,g) { i|=0;g|=0; if(!b&&p&&!p.ingredients) while((g=ic(p[g].ingredients,o,0,g+1))&&p[g]); else { o[p[i]]=(o[p[i]]|0)+1; return p[i+1]?ic(p,o,i+1,b):b; } } var ingredientCount = {}; ic(products, ingredientCount); document.body.innerHTML = JSON.stringify(ingredientCount).replace(/(\\,)/g,"$1<br/>");

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EDIT: No i'm not serious. 编辑：不，我不认真。 But its almost 3x faster 但是它快了将近3倍

从多维数组JavaScript中提取特定值

问题描述

2 个解决方案

解决方案1
1 2015-03-28 03:38:30

解决方案2
0 2015-03-28 02:57:35

从多维数组JavaScript中提取特定值

问题描述

2 个解决方案

解决方案1 1 2015-03-28 03:38:30

解决方案2 0 2015-03-28 02:57:35

解决方案1
1 2015-03-28 03:38:30

解决方案2
0 2015-03-28 02:57:35