Combine array of string and number as object array conditionally

Question

I have two array, one is type of String and second one is number. How can I combine these conditionally as key value objects.

For example:

var fruits = [
  "Apple",
  "Banana" ,
  "Apricot",
  "Bilberry"
]

var count = [3,5,0,2]

I want to combine fruits and count array as key value object and which count is not 0

Expected:

var merge = [{"Apple":3},{"Banana" :5},{"Bilberry":2}]

What i have tried is:

var merge = _.zipObject(["Apple","Banana" ,"Apricot","Bilberry"], [3,5,0,2])

and result is:

{"Apple":3,"Banana":5 ,"Apricot":0,"Bilberry":2}

why not loop thorugh and do it yourself. i don't think there is any readymade function for this — Abhishek
– Abhishek, Commented Mar 22, 2018 at 10:00

gurvinder372 · Accepted Answer · 2018-03-22 10:06:32Z

2

Try this vanilla js solution as well using filter, Object.values and map

var output = count.map((s, i) => ({
  [fruits[i]]: s
})).filter(s => Object.values(s)[0]);

Demo

var fruits = [
  "Apple",
  "Banana",
  "Apricot",
  "Bilberry"
];

var count = [3, 5, 0, 2];

var output = count.map((s, i) => ({
  [fruits[i]]: s
})).filter(s => Object.values(s)[0]);

console.log(output);

edited Mar 22, 2018 at 10:06

answered Mar 22, 2018 at 9:58

gurvinder372

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2 Comments

user3297291 Over a year ago

You might want to first map and only then filter, since the counts are now shifting one index away from the fruits.

gurvinder372 Over a year ago

@user3297291 You are right about it, I have updated the answer.

Ori Drori · Accepted Answer · 2018-03-22 10:06:14Z

Create the object with _.zipObject(), and then use _.pickBy() to filter keys with 0 values.

Note: _.pickBy() accepts a callback. The default is identity, which will filter all falsy values (false, 0, null, undefined, etc...). If you want to filter just zeroes, supply another callback, for example (v) => v !== 0.

var fruits = ["Apple", "Banana", "Apricot", "Bilberry"];
var count = [3,5,0,2];

var result = _.pickBy(_.zipObject(fruits, count));

console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.5/lodash.min.js"></script>

With vanilla JS, you can use Array.reduce():

var fruits = ["Apple", "Banana", "Apricot", "Bilberry"];
var count = [3,5,0,2];

var result = fruits.reduce(function(r, f, i) {
  if(count[i]) r[f] = count[i];
  
  return r;
}, {});

console.log(result);

brk · Accepted Answer · 2018-03-22 10:09:07Z

0

You can use map to create a new array of objects & filter to remove the undefined

The source of undefined is teh callback function is not returning any value when the count is 0

var fruits = [
  "Apple",
  "Banana",
  "Apricot",
  "Bilberry"
]

var count = [3, 5, 0, 2]
var newArr = count.map(function(item, index) {
  if (item !== 0) {
    return {
      [fruits[index]]: item
    }
  }
}).filter(function(item) {
  return item !== undefined;

})

console.log(newArr)

answered Mar 22, 2018 at 10:09

brk

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Comments

user3297291 · Accepted Answer · 2018-03-22 10:17:37Z

The two utility functions I think you're looking for are:

zip, to go from [ a, b ] + [ 1, 2 ] -> [ [ a, 1 ], [ b, 2 ] ]
fromPair to go from [ a, 1 ] -> { a: 1 }

Splitting the transformation in these two steps allows you to filter your list of key-value-pairs, which ensures you don't loose track of the link by index:

const valueFilter = ([k, v]) => v !== 0;

Possible implementations for those functions are:

const zip = (xs, ...others) =>
  xs.map(
    (x, i) => [x].concat(others.map(ys => ys[i]))
  );

const fromPair = ([k, v]) => ({ [k]: v });

With those utilities, you can do:

// Utils
const zip = (xs, ...others) =>
  xs.map(
    (x, i) => [x].concat(others.map(ys => ys[i]))
  );
  
const fromPair = ([k, v]) => ({ [k]: v });

// Data
const fruits = [ "Apple", "Banana", "Apricot", "Bilberry" ];
const counts = [3,5,0,2];

// App
const valueNotZero = ([k, v]) => v !== 0;

console.log(
  zip(fruits, counts)
    .filter(valueNotZero)
    .map(fromPair)
)

Ahsan Ali · Accepted Answer · 2018-03-22 10:59:49Z

0

With simple forEach

var fruits = [
  "Apple",
  "Banana",
  "Apricot",
  "Bilberry"
]

var count = [3, 5, 0, 2];
var merge = [];

fruits.forEach((val, i) => {
  if (count[i]) { merge.push({ [val]: count[i] }) };
});

console.log(merge);

answered Mar 22, 2018 at 10:59

Ahsan Ali

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