Javascript - sort array based on another array

Question

Is it possible to sort and rearrange an array that looks like this:

itemsArray = [ 
    [\'Anne\', \'a\'],
    [\'Bob\', \'b\'],
    [\'Henry\', \'b\'],
             


        

Answer 1

Why not something like

//array1: array of elements to be sorted
//array2: array with the indexes

array1 = array2.map((object, i) => array1[object]);

The map function may not be available on all versions of Javascript

Answer 2

One Line answer.

itemsArray.sort(function(a, b){  
  return sortingArr.indexOf(a) - sortingArr.indexOf(b);
});

Answer 3

Case 1: Original Question (No Libraries)

Plenty of other answers that work. :)

Case 2: Original Question (Lodash.js or Underscore.js)

var groups = _.groupBy(itemArray, 1);
var result = _.map(sortArray, function (i) { return groups[i].shift(); });

Case 3: Sort Array1 as if it were Array2

I'm guessing that most people came here looking for an equivalent to PHP's array_multisort (I did) so I thought I'd post that answer as well. There are a couple options:

1. There's an existing JS implementation of array_multisort(). Thanks to @Adnan for pointing it out in the comments. It is pretty large, though.

2. Write your own. (JSFiddle demo)

function refSort (targetData, refData) {
  // Create an array of indices [0, 1, 2, ...N].
  var indices = Object.keys(refData);

  // Sort array of indices according to the reference data.
  indices.sort(function(indexA, indexB) {
    if (refData[indexA] < refData[indexB]) {
      return -1;
    } else if (refData[indexA] > refData[indexB]) {
      return 1;
    }
    return 0;
  });

  // Map array of indices to corresponding values of the target array.
  return indices.map(function(index) {
    return targetData[index];
  });
}

3. Lodash.js or Underscore.js (both popular, smaller libraries that focus on performance) offer helper functions that allow you to do this:

    var result = _.chain(sortArray)
      .pairs()
      .sortBy(1)
      .map(function (i) { return itemArray[i[0]]; })
      .value();

...Which will (1) group the sortArray into [index, value] pairs, (2) sort them by the value (you can also provide a callback here), (3) replace each of the pairs with the item from the itemArray at the index the pair originated from.

Answer 4

function sortFunc(a, b) {
  var sortingArr = ["A", "B", "C"];
  return sortingArr.indexOf(a.type) - sortingArr.indexOf(b.type);
}

const itemsArray = [
  {
    type: "A",
  },
  {
    type: "C",
  },
  {
    type: "B",
  },
];
console.log(itemsArray);
itemsArray.sort(sortFunc);
console.log(itemsArray);

Answer 5

Something like:

items = [ 
    ['Anne', 'a'],
    ['Bob', 'b'],
    ['Henry', 'b'],
    ['Andrew', 'd'],
    ['Jason', 'c'],
    ['Thomas', 'b']
]

sorting = [ 'b', 'c', 'b', 'b', 'c', 'd' ];
result = []

sorting.forEach(function(key) {
    var found = false;
    items = items.filter(function(item) {
        if(!found && item[1] == key) {
            result.push(item);
            found = true;
            return false;
        } else 
            return true;
    })
})

result.forEach(function(item) {
    document.writeln(item[0]) /// Bob Jason Henry Thomas Andrew
})

Here's a shorter code, but it destroys the sorting array:

result = items.map(function(item) {
    var n = sorting.indexOf(item[1]);
    sorting[n] = '';
    return [n, item]
}).sort().map(function(j) { return j[1] })

Answer 6

I would use an intermediary object (itemsMap), thus avoiding quadratic complexity:

function createItemsMap(itemsArray) { // {"a": ["Anne"], "b": ["Bob", "Henry"], …}
  var itemsMap = {};
  for (var i = 0, item; (item = itemsArray[i]); ++i) {
    (itemsMap[item[1]] || (itemsMap[item[1]] = [])).push(item[0]);
  }
  return itemsMap;
}

function sortByKeys(itemsArray, sortingArr) {
  var itemsMap = createItemsMap(itemsArray), result = [];
  for (var i = 0; i < sortingArr.length; ++i) {
    var key = sortingArr[i];
    result.push([itemsMap[key].shift(), key]);
  }
  return result;
}

See http://jsfiddle.net/eUskE/