How to combine same strings in array?

Question

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.

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– obscure, Commented May 14, 2019 at 12:16
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– T.J. Crowder, Commented May 14, 2019 at 12:17

Bryan · Accepted Answer · 2019-05-14 12:34:29Z

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 }

I loop over the array
I split the element (eg. '1kg Carrots') into the weight and item
then I coerce the 1kg into an integer
I check if the obj already has a key of item and if it doesn't I add it
If it does already exist I just increment kgNum
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 :)

answered May 14, 2019 at 12:34

Bryan

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Comments

Harish · Accepted Answer · 2019-05-14 12:32:24Z

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]

answered May 14, 2019 at 12:32

Harish

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1 Comment

Uchivaru Kanda Over a year ago

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 :)

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