Count Distinct by Grouping

Hi,

This is a very simple thing but I cant seem to get to the bottom of it.

I need to create a measure that gives me the count distinct by a grouping.

For example

TableA

Group   Attributes

1               A

1               B

2               C

2               C

3               D

So the measure should say,

Group   Attributes    Measure (distinct values)

1               A                       2

1               B                       2

2               C                       1

2               C                       1

3               D                       1

So not that dissimilar to what a count distinct and group by clause would do in SQL.

Thanks a bunch!