Moving minimum (moving window)

RVhydrA

Does anyone know how to calculate a moving minimum (or for that matter how to iteratively select X number of lag rows and do anything to them such as calculate a min, max, range, etc. In this specific example i want to look back over say the last 100 rows and get the minimum value, then move to the next row down and do the same again (over and over). 

vince_faller

Would something like this work?

 

Names default to here( 1 );
dt = open("$SAMPLE_DATA\Big Class.jmp");

dt << New Column("Min height 5 back", 
	Formula(
		Min( // since we want a minumum 
			:height[// the column we want the minimum of
				// a slice of the current row minus 5 (minimum 1 so it's still on the datatable)
				// and current row
				Min( Row() - 5 )::Row() 
			] 
		)
	)
);