Retrieving values in crossfilter.dimension

Question

Hi I'm a newbie in JS and Crossfilter. I'm using crossfilter with my data (.csv file) and retrieved distinct values in a column using

var scoreDim = ppr.dimension(function (d) {
    return d.score;
});

Also I could get the counts for each value using

var scoreDimGroup = scoreDim.group().reduceCount();

I could use dc.js to plot the chart and the result looks correct. But how do I retrieve the values in scoreDim and scoreDimGroup so that I can use it for further processing in my code. When I look at the object using a debugger, I could see a bunch of functions but could not see the actual values contained in the objects.

Cautionary

Answer 1

scoreDim.top(Infinity)

will retrieve the records.

scoreDimGroup.top(Infinity)

will retrieve the groups (key-value pairs of the dimension value and the count).

Generally, this kind of thing is covered well in the Crossfilter API documentation.

Fecundate

For groups only you can shorten to .all() – Ski

Be careful that this will not return the filtered dim values. If you apply a filter on another dimension, the list of key for the dimension you get is always the full one with the method above ! – Sobriquet

Answer 2

You can use the top method of the group object:

var groupings = teamMemberGroup.top(Infinity);

This returns an array of groups, which will have the structure that you built in the reduce method. For example, to output the key and value you can do this: groupings.forEach(function (x) { console.log(x.key + x.value.projectCount); });

You can access the dimension values in the same way:

var dimData = teamMemberDimension.top(Infinity);
    dimData.forEach(function (x) {
        console.log(JSON.stringify(x));
    });

Here is a simple example of this: http://jsfiddle.net/djmartin_umich/T5v4N/

Rusty has a nice tutorial on how this works at http://blog.rusty.io/2012/09/17/crossfilter-tutorial/

Dola

Answer 3

If you are looking to view these values in the console then you can use this print_filter function that was mentioned in the tutorial!

(http://www.codeproject.com/Articles/693841/Making-Dashboards-with-Dc-js-Part-1-Using-Crossfil)

Basically you would include this bit of code in your javascript rendering of the crossfilter charts before you define your data source or your ndx variable:

function print_filter(filter) {
    var f = eval(filter);
    if (typeof(f.length) != "undefined") {}else{}
    if (typeof(f.top) != "undefined") {f=f.top(Infinity);}else{}
    if (typeof(f.dimension) != "undefined") {f=f.dimension(function(d) { return "";}).top(Infinity);}else{}
    console.log(filter+"("+f.length+") = "+JSON.stringify(f).replace("[","[\n\t").replace(/}\,/g,"},\n\t").replace("]","\n]"));
    };

Then you can simply run print_filter(scoreDim) in your console! It's that simple! You can use this to see all of the objects you create using crossfilter including groups, etc.

Hope this helps!

Hissing