UnderscoreJS: groupby + sortby

Question

Any suggestion on how to do grupby + sortby together using UnderscoreJS?

Having following collection, I would like to find smallest price per season:

var d = [{ 
    "price": 27.25,
    "season": 2
},
{ 
    "price": 10,
    "season": 3
},
{ 
    "price": 21,
    "season": 2
}];

I was able to group using the below:

_.chain(d).groupBy('season').map(function(value, key) {
return {
            season: key,
            obj: value

        }
    }).value();

which gets me:

[
 {"season":"2","obj":[{"price":27.25,"season":2},{"price":21,"season":2}]},
 {"season":"3","obj":[{"price":10,"season":3}]}
] 

Answer 1

Try this:

var output = _.chain(d).groupBy("season").map(function (group) {
    return _.chain(group).sortBy("price").first().value();
}).value();

See the demo: http://jsfiddle.net/Ns2MJ/

Answer 2

Get the minimum price of each season in your map function:

_.chain(d).groupBy('season').map(function(value, key) {
  return {
    season: key,
    price: _.chain(value).pluck('price').min().value()
  }
}).sortBy('price').value();

Answer 3

You can use _min combined with _.property to extract the smallest price in a group:

var output = _.chain(d).groupBy('season').map(function (group) {
    return _.min(group, _.property('price'));
}).value();

And a demo http://jsfiddle.net/nikoshr/Edf5g/