如何对数组内对象中具有相同键的所有值求和并求平均值

Question

so i have this json and i need to add the values of each the same keys that the object has and will also compute their average, here is my json

var arraySeries = [{"country":"United States","data":2},
                   {"country":"Venezuela","data":0},
                   {"country":"Singapore","data":3},
                   {"country":"United States","data":0},
                   {"country":"Germany","data":2},
                   {"country":"United States","data":2},
                   {"country":"Canada","data":2},
                   {"country":"Germany","data":-4}];

and here is my expected result

var newArraySeries = [{"country":"United States","data":[1.33333]},
                   {"country":"Venezuela","data":[0]},
                   {"country":"Singapore","data":[3]},
                   {"country":"Canada","data":[2]},
                   {"country":"Germany","data":[-1]}];

the data in newArraySeries should be in array, I'm going to use it in my highchart map.. i did some google research but i can't find any article like this.I hope you can help me

Answer 1

Solved with standard javascript and using temp variables

var countries = {}
var countries_count = {}
var newArraySeries = []
arraySeries.forEach(
    function(e){
        if(!countries[e.country]){
            countries[e.country] = 0
            countries_count[e.country] = 0
        }
        countries[e.country] += e.data
        countries_count[e.country]++
    }
)
for(var country in countries){
    newArraySeries.push({country : country, data : countries[country] / countries_count[country]})
}

Answer 2

You can do it with Alasql library.

var arraySeries = [{"country":"United States","data":2},
           {"country":"Venezuela","data":0}];

var res = alasql('SELECT country, AVG(data) AS data FROM ? GROUP BY country',
                  [arraySeries]);

Try this example at jsFiddle.