varying behavior of Summary in JSL?

hardner

Can someone explain this?

dt=	newtable("test", Add Rows( 8 ),
	New Column( "A",Character,Nominal,Set Selected,
		Set Values({"apple", "apple", "apple", "apple", "pear", "pear", "pear", "pear"})
	),
	New Column( "B",Character,Nominal,
		Set Values({"red", "green", "red", "yellow", "yellow", "yellow", "pink", "pink"})
	)

);

//first way - this summarizes everything, not just apple rows

dtsummary1=dt<<summary(group(:B),where(:A=="apple"));

//second way - this summarizes only apple rows like I wanted

currentdatatable(dt);

dtsummary2=summary(group(:B),where(:A=="apple"));

I can just use the second way but I don't understand this behavior. Why doesn't Where work the same?  Is there some smarter way to get the B values for just apple rows?

chungwei

Note that summary itself does not parse the where clause.

In the first case, you are sending the summary message to the data table dt.

Summary resolves what it understands, which in this case is the grouping column.

The second case behaves like a platform. The platform resolves the data table and sends the message to it.

In this case, the data table is the subset where :A=="apple".