Adding Duplicated array values

Question

I Have an array [[Food , quantity]] with duplicated values and i want to add the quantities of the same food in the array but i can't seem to find a way to do that

I want to do this using JavaScript and the array looks like this:

[
  ["Burger", 5],
  ["Pizza", 10],
  ["Coke", 13],
  ["Burger", 7],
  ["Soda", 10],
  ["Pizza", 4],
  ["Burger", 12]
]

and i want the result to be like:

[
  ["Burger", 24],
  ["Pizza", 14],
  ["Coke", 13],
  ["Soda", 10]
]

And then I want to display the result on a table

Does the order of elements matter ? or it should be in some sorted manner ? — Code Maniac
– Code Maniac, Commented Jun 6, 2019 at 11:58
Possible duplicate of Most efficient method to groupby on a array of objects — Alon Yampolski
– Alon Yampolski, Commented Jun 6, 2019 at 11:59

adiga · Accepted Answer · 2019-06-06 12:13:52Z

4

You could use reduce to group each food. Create an accumulator with each food as key and the sum of quantity as value. If the key is already added, increment it. Else, add the key with quantity as value. Then use Object.entries() to get a 2D array of food - total quantity pairs

const input=[["Burger",5],["Pizza",10],["Coke",13],["Burger",7],["Soda",10],["Pizza",4],["Burger",12]]

const counter = input.reduce((acc, [food, value]) => {
  acc[food] = acc[food] + value || value;
  return acc;
}, {});

const ouptut = Object.entries(counter)

console.log(JSON.stringify(ouptut))

This is what the accumulator/ counter object will look like:

{
  "Burger": 24,
  "Pizza": 14,
  "Coke": 13,
  "Soda": 10
}

edited Jun 6, 2019 at 12:13

answered Jun 6, 2019 at 12:03

adiga

35.4k9 gold badges65 silver badges88 bronze badges

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

Comments

Pranav Kale · Accepted Answer · 2019-06-06 12:03:51Z

0

You can try something like -

const arr = [["Burger" , 5], ["Pizza" , 10], ["Coke" , 13], ["Burger" , 7], ["Soda" , 10], ["Pizza" , 4], ["Burger" , 12]];

let ans = [];
arr.map((x) => {
	const [name, qty] = x;
  const found = ans.find((y) => y[0] === name);
  if(found){
  	found[1] = found[1] + qty;
  } else {
  	ans.push(x);
  }
});
console.log(ans);

answered Jun 6, 2019 at 12:03

Pranav Kale

6391 gold badge5 silver badges13 bronze badges

1 Comment

Andy Over a year ago

How does this work? What does map do, for example?

Manish Khedekar · Accepted Answer · 2019-06-06 12:05:40Z

0

You may try out like,

let array = [["Burger" , 5], ["Pizza" , 10], ["Coke" , 13], ["Burger" , 7], ["Soda" , 10], ["Pizza" , 4], ["Burger" , 12]];

let itemObj = {};

for(let item of array){
  if(itemObj.hasOwnProperty(item[0]))
    itemObj[item[0]] += item[1];
  else
    itemObj[item[0]] = item[1];
}

console.log(itemObj);

let newArray = Object.keys(itemObj).map(function(key) {
  return [key, itemObj[key]];
});

console.log(newArray);

answered Jun 6, 2019 at 12:05

Manish Khedekar

4024 silver badges13 bronze badges

Collectives™ on Stack Overflow

Adding Duplicated array values

3 Answers 3

Comments

1 Comment

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related