How to get random items from two dimensional array in node.js [duplicate]

Question

I have a two-dimensional array of latitudes and longitudes as below -

arrLoc = [
       [18.3, 70.2],
       [20.5, 75.4],
       [19.3, 50.7],
       [14.9, 40.5],

      ..... and so on, up to 10 items

I want to pick up a random lat-long from this array, for my further coding.

How to get a random item from this two-dimensional array?

That's for single-dimensional array. Won't work. I don't want to involve jQuery. — NetYogi
– NetYogi, Commented Dec 10, 2016 at 13:56
Your arrLoc is not an Array but looks more like an Object although wrong syntax. The answer there is javascript and doesn't involve jQuery. May be give the exact value of arrLoc here. — sabithpocker
– sabithpocker, Commented Dec 10, 2016 at 13:58
@NetYogi, this ain't really a two-imensional Array, logically it is a one-dimensional Array of Coordinates. Just that your coordinates are representad by an Array instead of an Object. [18.3, 70.2] instead of {lat: 18.3, lng: 70.2}. Take another look at how to get a random Value from an Array — Thomas
– Thomas, Commented Dec 10, 2016 at 14:40

michaPau · Accepted Answer · 2016-12-10 15:12:20Z

1

To get random values from your arrLoc definition just use Math.random

var arrLoc = [
       [18.3, 70.2],
       [20.5, 75.4],
       [19.3, 50.7],
       [14.9, 40.5]
  ];

  //random pair
  var randIndex = Math.floor(Math.random() * arrLoc.length);
  console.log("Latitude:"+arrLoc[randIndex][0]+", Longitude:"+arrLoc[randIndex][1]);

  //two random values
  var rand1 = Math.floor(Math.random() * arrLoc.length);
  var rand2 = Math.floor(Math.random() * arrLoc.length);
  console.log("Latitude:"+arrLoc[rand1][0]+", Longitude:"+arrLoc[rand2][1]);

No need to accept it as an answer, Stack overflow has already answers for this

edited Dec 10, 2016 at 15:12

answered Dec 10, 2016 at 15:07

michaPau

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3 Comments

Thomas Over a year ago

Math.floor() + arrLoc.length-1 is wrong, this would never select the last item in the Array. Math.floor( Math.random() * arrLoc.length )

michaPau Over a year ago

Yes , thanks, it's updated

NetYogi Over a year ago

Thanks @michaPau, @Thomas! The first code snippet (random pair) worked for me. The second one (two random pairs), as named, gives random values from different cells.

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