How-to applymap() a calculated expression to a desc. field
Referring to the title above, would anyone know how I can go about doing this?
The situation that I am facing is as such, 1 dim --> UserID, has a time-stamp associated with it (whenever the user uses the service, a time-stamp is generated). I am calculating an expression based on the MAX(DATE) - MIN(DATE) to find out the range of days he/she has been actively using the service. Once that expression has been computed, am going to compute another expression -- having an if(MAX(DATE) - MIN(DATE) <= 90, '1-3 Months', ...) naming it [ActiveMths_GROUP].
Now that is done, I would like to GROUP the number of users based on the previously calculated expression --> [ActiveMths_GROUP]. I have been trying a few methods, even using applymap() in an expression, but have failed terribly.
Please help!. Thanks in advance. Much appreciated.