Sequential array extraction to individual arrays in Javascript

Question

I have an array with 1000 elements in it. However, the array follows a sequence - every ten elements.e.g. [fruit,vegetables,sugars,bread,fruit,vegetables,sugars ....].

I would need to extract every fruit, vegetable and so on into different arrays, however there are 10 classes of them and I need to make ten different arrays out of this one.

What would be the most reliable approach to this problem?

Work is on JavaScript

In your 1000 element array, do you know what category they are? — James
– James, Commented Jan 15, 2018 at 16:07
Yes, I know the the categories there are ten of them which follow a sequence throughout the 100 elements. — SomethingCool
– SomethingCool, Commented Jan 15, 2018 at 16:07
The example of the array is written, I have achieved success in smaller array which only had 3 categories. So %3==0 to extract the third element and make a temp array, where later i extract the other element by using %2==0 from the temp array — SomethingCool
– SomethingCool, Commented Jan 15, 2018 at 16:10
Can you give me a 15 element example of your array? Is it a multidimensional array? — James
– James, Commented Jan 15, 2018 at 16:55

Nina Scholz · Accepted Answer · 2018-01-17 21:23:40Z

1

You could take an array with references to the wanted arrays and as index for the array for pusing the remainder value of the actual index and the length of the temporary array.

var array = ['fruit', 'vegetables', 'sugars', 'bread', 'fruit', 'vegetables', 'sugars', 'bread'],
    fruits = [],      // final arrays
    vegetables = [], //
    sugars = [],    //
    breads = [],   //
    temp = [fruits, vegetables, sugars, breads],
    len = temp.length;
    
array.forEach((v, i) => temp[i % len].push(v));
    
console.log(fruits);
console.log(vegetables);
console.log(sugars);
console.log(breads);

.as-console-wrapper { max-height: 100% !important; top: 0; }

edited Jan 17, 2018 at 21:23

answered Jan 15, 2018 at 16:18

Nina Scholz

388k26 gold badges367 silver badges417 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

SomethingCool Over a year ago

The elements them self dont repeat (they are different each time) but they follow a sequence. I have 10 different categories that i need to extract from that array.*The elements are not identical*

Nina Scholz Over a year ago

i took only four instead of then. the content could be different. this is just an example with a smaller subset.

Mark Schultheiss Over a year ago

As written this modifies the window.length value, just pointing that out.

I wrestled a bear once. · Accepted Answer · 2018-01-15 16:42:42Z

0

Not super elegant but it will do the job..

var a = 
 ['bread_1','fruit_1','vegetable_1','sugars_1',
  'bread_2','fruit_2','vegetable_2','sugars_2',
  'bread_3','fruit_3','vegetable_3','sugars_3'];
  
var i=0; 
a = a.reduce(function(ac, va, id, ar){
  if(i==ac.length) i=0;
  ac[i].push(va);
  i++;
  return ac;
}, [[],[],[],[]]);

console.log(a);

answered Jan 15, 2018 at 16:42

I wrestled a bear once.

23.5k20 gold badges74 silver badges122 bronze badges

Comments

James · Accepted Answer · 2018-01-15 17:47:12Z

I suggest (since the pattern may vary) to create an array with categories and what elements those categories include, thus creating an object with keys identifying your categories.

The variables are not 'declared' outside the object but you can access the object keys the same way you'd have different variables:

// Simple old-style catalog as reference for your elements array.
var Categories = {
    'fruits': ['orange', 'apple', 'all other fruits…'],
    'vegetables': ['ginger', 'broccoli', 'all other vegetables…'],
    'bread': ['pizza', 'panini', 'all other breads…'],
    'sugars': ['soda', 'sugar1', '90_percent_of_products_are_sugar', 'all other sugars…']
};

// Your actual elements array.
var ElementsArray = [
    'orange',
    'broccoli',
    'pizza',
    'sugar1',
    'apple',
    'ginger',
    'panini',
    'soda'
];

// Your organized-by-category variable, declare as object so you can easily access as Array or Object (keys are the variable arrays).
var OrderedElementsArray = {};

for (element in ElementsArray)
{
    for (category in Categories)
    {
        // Check if the key is not an array an initialize it for later use of push().
        if (typeof OrderedElementsArray[category] != 'object')
        {
            OrderedElementsArray[category] = [];
        }

        // indexOf() returns -1 if no element matches an index, thus the expression `>= 0`.
        if (Categories[category].indexOf(ElementsArray[element]) >= 0)
        {
            OrderedElementsArray[category].push(ElementsArray[element]);
        }
    }
}

// Here you can access your object variables with dot notation. All your categories will be accessible either way.
console.log(OrderedElementsArray.fruits);
console.log(OrderedElementsArray.vegetables);
console.log(OrderedElementsArray.bread);
console.log(OrderedElementsArray.sugars);

// Here you can access your object variables with key notation. All your categories will be accessible either way.
console.log(OrderedElementsArray['fruits']);
console.log(OrderedElementsArray['vegetables']);
console.log(OrderedElementsArray['bread']);
console.log(OrderedElementsArray['sugars']);

Collectives™ on Stack Overflow

Sequential array extraction to individual arrays in Javascript

3 Answers 3

3 Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

3 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related