An example of multidimensional filtering (crossfiltering) using histograms and brushing, where the sets of data that match various numbers of filters are highlighted. The lightest color matches no filters, the darkest matches all filters. If you have two brushes, there is a mid-range color that shows the data that matches either of the two filters, and so on as you add more brushes. Shows the Iris dataset. Leverages d3-rosetta.