Arranging array based on the sequence of another array

Question

Arranging array based on the sequence of another array

There are two arrays that I am working with:

Main array:

const items = [
  "Лопата 123",
  "Empty Forest",
  "Forever young",
  "My ears",
  "Most Important",
  "16 Tons",
  "Operation Flashpoint",
  "Prize A1",
  "Нарешті літо",
];

And keys array:

const keys = ["Prize A1", "Forever young", "Most Important"];

The goal is to sort the main array based on the order of the keys array, like this:

const expected = [
  "Prize A1",
  "Forever young",
  "Most Important",
  "Лопата 123",
  "Empty Forest",
  "My ears",
  "16 Tons",
  "Operation Flashpoint",
  "Нарешті літо",
]

I tried to write some code to achieve this, but it's not working correctly:

const expectedOrder = items.sort(function(a, b) {
   return keys.indexOf(b) - keys.indexOf(a);
});

 const items = [
    "Лопата 123",
    "Empty Forest",
    "Forever young",
    "My ears",
    "Most Important",
    "16 Tons",
    "Operation Flashpoint",
    "Prize A1",
    "Нарешті літо",
  ];
    
const keys = ["Prize A1", "Forever young", "Most Important"];

const expectedOrder = items.sort(function(a, b) {
   return keys.indexOf(b) - keys.indexOf(a);
});

console.log('expectedOrder', expectedOrder)

javascript arrays sorting

Answer 1

Answer №1

To organize the items, consider using a default value of -1 for indices.

 const
     items = ["Лопата 123", "Empty Forest", "Forever young", "My ears", "Most Important", "16 Tons", "Operation Flashpoint", "Prize A1", "Нарешті літо"],
     keys = ["Prize A1", "Forever young", "Most Important"];

items.sort((a, b) => ((keys.indexOf(a) + 1) || Number.MAX_VALUE) - ((keys.indexOf(b) + 1) || Number.MAX_VALUE));

console.log(items);

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

A more concise method involves using an object for sorting with a default value.

 const
     items = ["Лопата 123", "Empty Forest", "Forever young", "My ears", "Most Important", "16 Tons", "Operation Flashpoint", "Prize A1", "Нарешті літо"],
     order = { "Prize A1": 1, "Forever young": 2, "Most Important": 3, default: Number.MAX_VALUE };

items.sort((a, b) => (order[a] || order.default) - (order[b] || order.default));

console.log(items);

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

Answer 2

To organize the items, consider using a default value of -1 for indices.

 const
     items = ["Лопата 123", "Empty Forest", "Forever young", "My ears", "Most Important", "16 Tons", "Operation Flashpoint", "Prize A1", "Нарешті літо"],
     keys = ["Prize A1", "Forever young", "Most Important"];

items.sort((a, b) => ((keys.indexOf(a) + 1) || Number.MAX_VALUE) - ((keys.indexOf(b) + 1) || Number.MAX_VALUE));

console.log(items);

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

A more concise method involves using an object for sorting with a default value.

 const
     items = ["Лопата 123", "Empty Forest", "Forever young", "My ears", "Most Important", "16 Tons", "Operation Flashpoint", "Prize A1", "Нарешті літо"],
     order = { "Prize A1": 1, "Forever young": 2, "Most Important": 3, default: Number.MAX_VALUE };

items.sort((a, b) => (order[a] || order.default) - (order[b] || order.default));

console.log(items);

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

Answer 3

Answer №2

Locate the positions of your keywords:

"Prize A1" = 0
"Forever young" = 1
"Most Important" = 2

Arranging the items in a certain order depending on their value relative to a reference value, for example "Prize A1" < "Most Important"

You can reverse the order of your keywords list:

const items = [
    'Лопата 123',
    'Empty Forest',
    'Forever young',
    'My ears',
    'Most Important',
    '16 Tons',
    'Operation Flashpoint',
    'Prize A1',
    'Нарешті літо',
];

const keywords = ['Prize A1', 'Forever young', 'Most Important'].reverse();

const expectedOrder = items.sort(function(a, b) {
    return keywords.indexOf(b) - keywords.indexOf(a);
});

console.log('expectedOrder', expectedOrder);

Answer 4

Locate the positions of your keywords:

"Prize A1" = 0
"Forever young" = 1
"Most Important" = 2

Arranging the items in a certain order depending on their value relative to a reference value, for example "Prize A1" < "Most Important"

You can reverse the order of your keywords list:

const items = [
    'Лопата 123',
    'Empty Forest',
    'Forever young',
    'My ears',
    'Most Important',
    '16 Tons',
    'Operation Flashpoint',
    'Prize A1',
    'Нарешті літо',
];

const keywords = ['Prize A1', 'Forever young', 'Most Important'].reverse();

const expectedOrder = items.sort(function(a, b) {
    return keywords.indexOf(b) - keywords.indexOf(a);
});

console.log('expectedOrder', expectedOrder);

Answer 5

Answer №3

To maintain the original order of the list, it is important to verify if the items are present in the keys array.

If both items are either included or not included in the keys array, then their positions remain unchanged. However, if only one of the items is included in the keys array, it should be arranged before the other item in the list.

 const items = [
    "Лопата 123",
    "Empty Forest",
    "Forever young",
    "My ears",
    "Most Important",
    "16 Tons",
    "Operation Flashpoint",
    "Prize A1",
    "Нарешті літо",
  ];
    
const keys = ["Prize A1", "Forever young", "Most Important"];

const expectedOrder = items.sort(function(a, b) {
   const incA = keys.includes(a);
   const incB = keys.includes(b);
   
   return (incA === incB)? 0 : ((incA)? -1 : 1);
});

console.log('expectedOrder', expectedOrder)

Answer 6

To maintain the original order of the list, it is important to verify if the items are present in the keys array.

If both items are either included or not included in the keys array, then their positions remain unchanged. However, if only one of the items is included in the keys array, it should be arranged before the other item in the list.

 const items = [
    "Лопата 123",
    "Empty Forest",
    "Forever young",
    "My ears",
    "Most Important",
    "16 Tons",
    "Operation Flashpoint",
    "Prize A1",
    "Нарешті літо",
  ];
    
const keys = ["Prize A1", "Forever young", "Most Important"];

const expectedOrder = items.sort(function(a, b) {
   const incA = keys.includes(a);
   const incB = keys.includes(b);
   
   return (incA === incB)? 0 : ((incA)? -1 : 1);
});

console.log('expectedOrder', expectedOrder)

Arranging array based on the sequence of another array

Answer №1

Answer №2

Answer №3

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