why does one chart not filter another in dc.js?

Question

I am not able to understand how dc groups chart. So that the change in one filter reflects in all others. I have a simple code with two series charts. When I draw brush on one, it does not filter the other. Not sure why ? Can someone please have a quick look at the small code and suggest.

d3.csv("data/compareData.txt", function(data) {

  ndx = crossfilter(data);
  runDimension = ndx.dimension(function(d) {return [+d3.time.format.iso.parse(d.timestamp), +d.meterid]; });
  frequencyGroup = runDimension.group().reduceSum(function(d) { return +d.frequency; });
  magnitudeGroup = runDimension.group().reduceSum(function(d) { return +d.magnitude; });


 frequencyChart
    .width(768)
    .height(480)
    .chart(function(c) { return dc.lineChart(c).interpolate('basis'); })
    .x(d3.time.scale().domain([1366621166000, 1366621179983]))
    .y(d3.scale.linear().domain([90, 100]))
    .brushOn(true)
    .yAxisLabel("Measured Speed km/s")
    .xAxisLabel("Run")
    .elasticY(true)
    .dimension(runDimension)
    .group(frequencyGroup)
    .mouseZoomable(false)
    .seriesAccessor(function(d) {return +d.key[1];})
    .keyAccessor(function(d) {return +d.key[0];})
    .valueAccessor(function(d) {return +d.value;})
    .legend(dc.legend().x(350).y(350).itemHeight(13).gap(5).horizontal(1).legendWidth(140).itemWidth(70));
  frequencyChart.yAxis().tickFormat(function(d) {return d3.format(',d')(d);});
  frequencyChart.margins().left += 40;

 magnitudeChart
    .width(768)
    .height(480)
    .chart(function(c) { return dc.lineChart(c).interpolate('basis'); })
    .x(d3.time.scale().domain([1366621166000, 1366621179983]))
    .y(d3.scale.linear().domain([90, 100]))
    .brushOn(true)
    .yAxisLabel("Measured Speed km/s")
    .xAxisLabel("Run")
    .elasticY(true)
    .dimension(runDimension)
    .group(magnitudeGroup)
    .mouseZoomable(false)
    .seriesAccessor(function(d) {return  +d.key[1];})
    .keyAccessor(function(d) {return +d.key[0];})
    .valueAccessor(function(d) {return +d.value;})
    .legend(dc.legend().x(350).y(350).itemHeight(13).gap(5).horizontal(1).legendWidth(140).itemWidth(70));
  magnitudeChart.yAxis().tickFormat(function(d) {return d3.format(',d')(d);});
  magnitudeChart.margins().left += 40;

      dc.renderAll();

});

Answer 1

You are using the same dimension to group on both charts.

a grouping intersects the crossfilter's current filters, except for the associated dimension's filter. Thus, group methods consider only records that satisfy every filter except this dimension's filter. So, if the crossfilter of payments is filtered by type and total, then group by total only observes the filter by type.

from the crossfilter API doc

One solution is to create a runDimension2 similar to runDimension and do your second chart using this dimension instead.