Map dynamic key to values in Javascript array

Question

I need to map one object array into this format:

             "Brandenburg Gate, Berlin": {latitude: 52.516272, longitude: 13.377722},
             "Dortmund U-Tower": {latitude: 51.515, longitude: 7.453619},
             "London Eye": {latitude: 51.503333, longitude: -0.119722},
             "Kremlin, Moscow": {latitude: 55.751667, longitude: 37.617778},
             "Eiffel Tower, Paris": {latitude: 48.8583, longitude: 2.2945},
             "Riksdag building, Stockholm": {latitude: 59.3275, longitude: 18.0675},
             "Royal Palace, Oslo": {latitude: 59.916911, longitude: 10.727567}
             }

where my source array looks like

{place: "Brandenburg Gate, Berlin", latitude: 52.5, longitude 13.3   }

I can't figure out how to make place be the key of the array.

_.map(a, function (m) {return m.place: {longitude: m.longitude}})

is obviously wrong.

Answer 1

Iterate over the array, add each value to the object and delete the place property:

var obj = {};
arr.forEach(function(value) {
    obj[value.place] = value;
    delete value.place;
});

Answer 2

Try:

var result = {};
a.forEach(function (item) {
   result[item.place] = {longitude: item.longitude, latitude: item.latitude};
});

Answer 3

What is the expected result?

Maybe:

_.map(a, function (m) {
  return {"place":m.place, "longitude": m.longitude}
})

Answer 4

I assume you have an array of objects? If so, this will work (assuming you are using underscorejs based on _.map()):

var locationObject = {};
_(arrayOfLocations).each(function(location) {
  locationObject[location.place] = { latitude: location.latitude, longitude: location.longitude };
});

This will give you an object where the key is the place and the associated values are themselves objects containing the latitude and longitude.

Answer 5

You might try using obj.map() and re-map all the elements.

Here is an example:

<script type="text/javascript">
function experiment() {
var obj = [{place: "Brandenburg Gate, Berlin", latitude: 52.5, longitude: 13.3},
       {place: "Dortmund U-Tower", latitude: 51.515, longitude: 7.453619},
       {place: "London Eye", latitude: 51.503333, longitude: -0.119722}];

/* Mapped Output
"Brandenburg Gate, Berlin": {latitude: 52.516272, longitude: 13.377722},
"Dortmund U-Tower": {latitude: 51.515, longitude: 7.453619},
"London Eye": {latitude: 51.503333, longitude: -0.119722},
*/

// create a new object array
var reformattedArray = obj.map(function(o){ 
    var rObj = {};
    rObj[o.place] = {latitude : o.latitude, longitude : o.longitude};
    return rObj;
});
}
window.onload = experiment;
</script>