How to extract values from a multidimensional array to form another array?

Question

So I have an array with 4 values: item, category, checked, number:

var MyArray = [
["coke", "beverages", "checked", 000],
["baguette", "bread", "checked", 001],
["water", "beverages", "checked", 000],
["pepsi", "beverages", "checked", 000],
["wholemeal", "bread", "checked", 001],
...
]

How do I make more arrays to categorise them like this:

var beverages = ["coke", "pepsi", "water"]; // more drinks from above array...
var bread = ["baguette", "wholemeal"]; // more types of bread from above array...

Any help would be appreciated, thanks!

You cannot create dynamic variable names, only dynamic keys of an object. You could e.g. create the following structure: var object = { beverages: [...], bread: [...] }; — ssc-hrep3
– ssc-hrep3, Commented May 21, 2019 at 17:48
What comes after "coke",... It's not obvious from the data — adiga
– adiga, Commented May 21, 2019 at 17:49
Are the items you want to group by always in the second position? Please show more data, perhaps with different beverages... — Heretic Monkey
– Heretic Monkey, Commented May 21, 2019 at 17:49

adiga · Accepted Answer · 2019-05-21 18:03:48Z

3

You could use reduce to group the items like this. Create an accumulator object with each type of food as key. Destructure each inner array to get the first and second item.

var MyArray = [
  ["coke", "beverages", "checked", 000],
  ["baguette", "bread", "checked", 001],
  ["water", "beverages", "checked", 000],
  ["pepsi", "beverages", "checked", 000],
  ["wholemeal", "bread", "checked", 001],
]

const grouped = MyArray.reduce((r, [item, type]) => {
  r[type] = r[type] || [];
  r[type].push(item)
  return r;
}, {})

const { bread, beverages } = grouped

console.log(bread, beverages)

This is how the grouped object will look. You can use destrucutring to get more categories of food

{
  "beverages": [ "coke", "water", "pepsi" ],
  "bread": [ "baguette", "wholemeal" ]
}

edited May 21, 2019 at 18:03

answered May 21, 2019 at 17:56

adiga

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2 Comments

Ashley Howard Over a year ago

Thanks for this! Which part of this code takes the bread and beverages' items? The const? Just asking in case in the future I want to add more categories.

adiga Over a year ago

@AshleyHoward I have updated the answer. From reduce, you get an object with each unique category as it's key. If you have more types, you can add the key names to the destructuring const { bread, beverages, dessert } = grouped

Shubham Verma · Accepted Answer · 2019-05-21 17:50:31Z

-2

It could be like this :

var beverages = MyArray.map(data =>  data[0])
var bread = MyArray.map(data =>  data[1]);

and so on.

answered May 21, 2019 at 17:50

Shubham Verma

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