Extract specific values from multidimensional array javascript
Question
I have a multidimensional array seen below. I wish extract all the ingredients values from it, and then do an action with them, like count how many of each there are.
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. Once for extracting all the ingredients, and then to make a hash style structure that counts up the number of times each ingredient occurs. I store these counts in a separate object, ingredientCount in this case.
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:
{ 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. Can anyone help me out? I apologize in advance if this is a duplicate question.
2 answers
solution1
1 2015-03-28 03:38:30
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).
var counts = products.reduce(function (result, product) {
product.ingredients.forEach(function (ingredient) {
result[ingredient] = (result[ingredient] || 0) + 1;
});
return result;
}, {});
solution2
0 2015-03-28 02:57:35
You could use recursion:
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. But its almost 3x faster
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