Is it possible to group by multiple dimensions in crossfilter?

Question

For Example If we have data for books, authors and date information. Can we build a crossfilter for how many books are present for author per month?

Answer 1

I didn't find the accepted answer all that helpful.

I used the following instead.

I first made a keyed group (in your case month)

   var authors = cf.dimension(function (d) {
     return +d['month'];
   })

Next, I used a map reduce method on the keyed dataset to compute the averages

The grouping helper function:

var monthsAvg = authors.group().reduce(reduceAddbooks, reduceRemovebooks, reduceInitialbooks).all();

The map-reduce functions:

function reduceAddbooks(p, v) {
    p.author = v['author'];
    p.books = +v['books'];
    return p;
}

function reduceRemovebooks(p, v) {
    p.author = v['author'];
    p.books = +v['books'];
    return p;
}

function reduceInitialbooks() {
    return {
        author:0,
        books:0
    };
}