fieldvaluecount - script function
This script function returns the number of distinct values in a field. fieldname must be given as a string (for example a quoted literal).
In this example the number of regions is counted and stored in the RegionCount variable. This value, 2 in this case, can then be used for further transformations where you need to know the number of existing regions.
LOAD * INLINE
[ Region, Year, Month, Sales
South, 2014, June, 645
North, 2014, May, 245
North, 2014, May, 347
North, 2014, June, 127
South, 2013, May, 367
South, 2013, July, 221 ];
Let RegionCount = FieldValueCount('Region');