Tips for organizing the elements of an array according to a specific rule

Question

Tips for organizing the elements of an array according to a specific rule

The array can vary in size but at most it could contain the following elements:

DE/FR/IT/EN/RM

Examples of possible arrays include:

DE/FR/IT/EN/RM,

IT/EN/RM,

DE/RM

and so on.

Is there a way to make an array like this adhere to a specific sorting rule? Specifically, how can I ensure that the array always sorts itself in this order: DE/FR/IT/EN/RM

I attempted to solve this issue with the following code, however, as I am not proficient in JavaScript, I struggle to understand its functionality:

function{
.....
....
...
list.sort(compareList());
...
..
.
}

function compareList() {
    var ruleList = new Array();
    ruleList.push("DE","FR","IT","EN","RM");


}

For example, if the input array contains 3 elements: RM,DE,EN

the sorted output should be: DE,EN,RM

Another scenario is with the maximum 5 elements: FR,DE,EN,RM,IT

which should output:DE,FR,IT,EN,RM

javascript arrays sorting

Answer 1

Answer №1

To organize a list based on specific values, you can assign an object with the desired order and a default value for unknown items, then sort the list by calculating the difference between the values. The unknown items will be placed at the end of the list.

function specifyOrder() {
    var order = { DE: 1, FR: 2, IT: 3, EN: 4, RM: 5, default: Infinity };
    return (a, b) => (order[a] || order.default) - (order[b] || order.default);
}

console.log(['RM', 'DE', 'EN'].sort(specifyOrder()));             // DE EN RM
console.log(['FR', 'DE', 'EN', 'RM', 'IT'].sort(specifyOrder())); // DE FR IT EN RM

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

To maintain the position of the first element in the list, you can assign it a significantly negative value for sorting purposes. This method is effective when the array order is known in advance, as there won't be any index information available for later sorts.

const
    keepFirstElement = (array, sort) => {
        var order = array.reduce((r, v, i) => (r[v] = i + 1, r), { default: Infinity });
        order[array[0]] = -Infinity;
        return array.sort((a, b) => (order[a] || order.default) - (order[b] || order.default));
    },
    order = ['DE', 'FR', 'IT', 'EN', 'RM'];

console.log(keepFirstElement(['RM', 'DE', 'EN'], order).join(' '));             // RM DE EN
console.log(keepFirstElement(['FR', 'DE', 'EN', 'RM', 'IT'], order).join(' ')); // FR DE IT EN RM

Answer 2

To organize a list based on specific values, you can assign an object with the desired order and a default value for unknown items, then sort the list by calculating the difference between the values. The unknown items will be placed at the end of the list.

function specifyOrder() {
    var order = { DE: 1, FR: 2, IT: 3, EN: 4, RM: 5, default: Infinity };
    return (a, b) => (order[a] || order.default) - (order[b] || order.default);
}

console.log(['RM', 'DE', 'EN'].sort(specifyOrder()));             // DE EN RM
console.log(['FR', 'DE', 'EN', 'RM', 'IT'].sort(specifyOrder())); // DE FR IT EN RM

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

To maintain the position of the first element in the list, you can assign it a significantly negative value for sorting purposes. This method is effective when the array order is known in advance, as there won't be any index information available for later sorts.

const
    keepFirstElement = (array, sort) => {
        var order = array.reduce((r, v, i) => (r[v] = i + 1, r), { default: Infinity });
        order[array[0]] = -Infinity;
        return array.sort((a, b) => (order[a] || order.default) - (order[b] || order.default));
    },
    order = ['DE', 'FR', 'IT', 'EN', 'RM'];

console.log(keepFirstElement(['RM', 'DE', 'EN'], order).join(' '));             // RM DE EN
console.log(keepFirstElement(['FR', 'DE', 'EN', 'RM', 'IT'], order).join(' ')); // FR DE IT EN RM

Answer 3

Answer №2

var baseLanguages = ["DE","FR","IT","EN","RM"];
var testLanguages = ["DE","IT","FR","EN"];
testLanguages.sort((a,b) => baseLanguages.indexOf(a) - baseLanguages.indexOf(b));
console.log(testLanguages);

The order can be determined by the index of the languages in the base array

var baseLanguages = ["DE","FR","IT","EN","RM"];
var testLanguages = ["DE","IT","FR","EN"];
testLanguages.sort((a,b) => baseLanguages.indexOf(a) - baseLanguages.indexOf(b));
console.log(testLanguages);

Answer 4

var baseLanguages = ["DE","FR","IT","EN","RM"];
var testLanguages = ["DE","IT","FR","EN"];
testLanguages.sort((a,b) => baseLanguages.indexOf(a) - baseLanguages.indexOf(b));
console.log(testLanguages);

The order can be determined by the index of the languages in the base array

var baseLanguages = ["DE","FR","IT","EN","RM"];
var testLanguages = ["DE","IT","FR","EN"];
testLanguages.sort((a,b) => baseLanguages.indexOf(a) - baseLanguages.indexOf(b));
console.log(testLanguages);

Answer 5

Answer №3

To achieve this functionality, you can create a function called sortArrayBy() like the following:

// Custom sorting function for sorting an array based on another array
function sortArrayBy(input, by) {

  var result = [].concat(input)

  result.sort(( str0, str1 ) => {

     const idx0 = by.indexOf(str0)
     const idx1 = by.indexOf(str1)

     // Handling cases where elements are not found in the 'by' array
     if(idx0 === -1) return 1
     if(idx1 === -1) return -1

     return idx0 - idx1
  })
  
  return result;
}

var data = ['DE','FR','IT','EN','RM']

console.log('DE/FR/IT/EN/RM', sortArrayBy(data, ['DE','FR','IT','EN','RM']))
console.log('IT/EN/RM', sortArrayBy(data, ['IT','EN','RM']))
console.log('DE/RM', sortArrayBy(data, ['DE','RM']))

The sortArrayBy() function allows you to specify an order (in the form of the index array by) for sorting the elements in the input array (e.g., ['DE','FR','IT','EN','RM']), producing the sorted array as the result.

Answer 6

To achieve this functionality, you can create a function called sortArrayBy() like the following:

// Custom sorting function for sorting an array based on another array
function sortArrayBy(input, by) {

  var result = [].concat(input)

  result.sort(( str0, str1 ) => {

     const idx0 = by.indexOf(str0)
     const idx1 = by.indexOf(str1)

     // Handling cases where elements are not found in the 'by' array
     if(idx0 === -1) return 1
     if(idx1 === -1) return -1

     return idx0 - idx1
  })
  
  return result;
}

var data = ['DE','FR','IT','EN','RM']

console.log('DE/FR/IT/EN/RM', sortArrayBy(data, ['DE','FR','IT','EN','RM']))
console.log('IT/EN/RM', sortArrayBy(data, ['IT','EN','RM']))
console.log('DE/RM', sortArrayBy(data, ['DE','RM']))

The sortArrayBy() function allows you to specify an order (in the form of the index array by) for sorting the elements in the input array (e.g., ['DE','FR','IT','EN','RM']), producing the sorted array as the result.

Tips for organizing the elements of an array according to a specific rule

Answer №1

Answer №2

Answer №3

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