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I am making my first project as a food rota that gives out a shopping list from the chosen Recipe ingredients. I managed to write the loop that would combine all the ingredients in one array where it takes us to my question.

I would like to combine the same ingredients in the array ie: [1kg Carrots, 1kg Spinach, 1kg Carrots], I would like it to combine the repeating (1kg Carrots, 1kg Carrots) into (2kg Carrots)

Is there a way to do this?

Sorry if my request is sloppy, first time asking a question.

I could work it so that it would cancel out the similar ones as the outcome of [1kg Carrots, 1kg Carrots] would be [1kg Carrot].

Unfortunately I am at work at the moment and do not have access - will update if needed.

Satyam Pathak
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Uchivaru Kanda
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    Welcome to StackOverflow! To help you we really need to see your code. – obscure May 14 '19 at 12:16
  • Welcome to Stack Overflow! Please take the [tour] (you get a badge!), have a look around, and read through the [help], in particular [*How do I ask a good question?*](/help/how-to-ask) I also recommend Jon Skeet's [Writing the Perfect Question](https://codeblog.jonskeet.uk/2010/08/29/writing-the-perfect-question/) and [Question Checklist](https://codeblog.jonskeet.uk/2012/11/24/stack-overflow-question-checklist/). The answers to [this question](https://stackoverflow.com/questions/1960473/get-all-unique-values-in-a-javascript-array-remove-duplicates) will get you going the right direction. – T.J. Crowder May 14 '19 at 12:17

2 Answers2

1

it can be done in 2 steps

var arr = ["1kg Carrots", "1kg Spinach", "1kg Carrots"]

step 1: count total number of kg

var arrCount = arr.reduce((ac, val)=> {
    var [kg, key] = val.split(' ')
    kg = parseFloat(kg) 
    ac[key] = ac[key]? ac[key]+kg : kg;
    return ac 
}, {}) // { Carrots: 2, Spinach: 1 }

step 2: revert it to array

var out  = Object.entries(arrCount).map(([key, kg])=> `${kg}kg ${key}`)
// [2kg Carrots, 1kg Carrots]
Harish
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  • Thanks, I will try this out as soon as I get home and will let you know the results It looks like this would definitely solve my problem though ( I dont necessarily need the kg part I can assume that anyway :) – Uchivaru Kanda May 14 '19 at 12:54
1

I would most likely create an object from the array. 

const arr = ['1kg Carrots', '1kg Spinach', '1kg Carrots'];
let obj = {};

arr.forEach(element => {
 let [kg, item] = element.split(' ');

 kgNum = parseInt(kg);

 if(Object.keys(obj).includes(item)){
  return obj[item] += kgNum;
 } else {
   obj[item] = kgNum;
 }
})
obj
// #=>  { Carrots: 2, Spinach: 1 }
  1. I loop over the array
  2. I split the element (eg. '1kg Carrots') into the weight and item
  3. then I coerce the 1kg into an integer
  4. I check if the obj already has a key of item and if it doesn't I add it
  5. If it does already exist I just increment kgNum
  6. and then I return the object

This is a good place to start and you can figure out with a little more work of how to add back the kg :)

Bryan
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