I'm sorry, this is probably a very easy question but I can't get my head around it. I think it might be solved by groups, but I'm not sure.
I want to create a bar chart, in my example, I've chosen 'favorite foods'. I'd like it so that it was a simple bar chart showing the three groups of food (ice cream, biscuits, cake) (as in graph 2), and then when the user clicked on the group, all the varities of that groupwere arrayed (graph 3). I can't get it to do this and I'm sure it must be possible!