calculate number of days between two dates

using the generate attribute operator you can use the Regular expressions, and build a query with the inbuilt date functions.
this would work to work the date diff okay, but to leave out the weekends not to sure.

this would be my pseudo code for the reg ex expression.

if date,
    then
          days = today - pref date
          weekday_count = days / 7 * 5
          return weekday_count
    else
          return date
to generate your new attribute "weekday_count"
check the "transaction date" attribute for a value.
count the difference, to get the total days then work out 5/7 to get the no of week days between the two.
return this value
otherwise return the date value for the example (i.e unknown)

Hello

There's an R package called "bizdays" that seems to have a function to do this.

So if you're prepared to install the R extension and learn how to integrate with R from RapidMiner that might be the easiest way to go.

There are some examples here that might help you up the learning curve http://rapidminernotes.blogspot.co.uk/search/label/R

Hope that helps...

regards

Andrew