How to wrap a group with a top method

Question

I have a map display and would like to total all electoral votes of the states that have been selected and display it in a number display. I was given the advice in a previous thread to wrap my group with an object with a top method. I'm not sure how to do this, so far I have:

var stateDim4 = ndx.dimension(function(d) { return d.state; }),
        group = stateDim4.group().reduceSum(function(d) {return d.elecVote }),
        count = group.top(51);
    count[0].key;
    count[0].value;

Please could someone help me on how to do this? Previous Thread: Summing a column and displaying percentage in a number chart

Answer 1

Building on your previous example, here is a fake group with a top method that sums up all the electoral votes for the selected states.

var fakeGroup = {
    top: function() {
    return [
        grp2.top(Infinity).reduce(function(a,b) {
        if(b.value > 0) {
          a.value += elecVotesMap.get(b.key)
        }
        return a
      }, {
        key: "",
        value: 0
      })
    ]
  }
}


percentElec
  .group(fakeGroup)
  .formatNumber(d3.format("d")) 

Here is a working JSFiddle: https://jsfiddle.net/esjewett/u9dq33v2/2/

There are a bunch of other fake group examples in the dc.js FAQ, but I don't think any of them do exactly what you want here.