RSsk5 Aggregating Groups In Matrix

Hi all.

I have what I thought would be a simple problem, maybe my approach is all wrong!

Say you have customers, registered in a year/month group. They can be active in another year/month group.

So we get a simple table with registration year/month down the side and activity along the top.

This shows "of all the people p who register in month m, how many are active in month a?"

So assuming that all people registered in month m are also active in month m, the max(activity) for that slice (ie the max value for any active month for the registered month) should be the value if we collapse the activemonth group to activeyear.

Let me try to draw it :D


Registered/Active
2006 2007 ...
Jan Feb Mar ... Jan Feb Mar ... ...
2 Jan 20 10 10 20 . 5 3 1 5 20
0 Feb 0 25 15 25 . 8 5 5 8 25
0 Mar 0 0 40 40 . 11 1 6 11 40
6 ... 20 35 65 65 . 24 9 12 24 85
2 Jan 0 0 0 0 . 50 34 44 34 50
0 Feb 0 0 0 0 . 0 45 40 41 45
7 ... 20 35 65 65 . 50 79 44 75 95
..... 20 35 65 65 . 74 88 56 99 180


I think. The ...'s represent the grouping band total.