Analysis with user selected columns - Scripting

[#1]

Trying to write a script to perform curve fitting based on user selected columns. 

In the example below, the goal is to fit linear with X and Y based on :Group and/or  :Type. User can select either or both columns and then run the script. 

This is what I've got

dt1 = current datatable();

sc = dt1 << get selected Columns;
scn= column (sc) << get name;

show (sc);
show (scn);

obj = dt1 <<Fit Curve(
	
	Y( :Y ),
	X( :X ),
    Fit linear,
	By( scn )
//  By (sn)
    );

In Log

show (sc); spits out:      sc = {:Group, :Type};

show (scn); spits out;      scn = "Group";

In Fit curves, neither "By (scn)" nor "By(sc)" can achieve the function of "By (:Group, :Type) or By(:Group).

What is the correct code to make this work?

Thanks!

[#2 · Accepted solution]

One option would be to add Eval() around scn:

Names Default To Here(1);

dt1 = Current Data Table();

sc = dt1 << get selected Columns;
scn = Column(sc) << get name;

Show(sc);
Show(scn);

obj = dt1 << Fit Curve(
	Y(:Y),
	X(:X),
	Fit linear,
	By(Eval(scn))//  By (sn)
);

[#3 · Accepted solution]

This works too:

Names Default To Here(1);

dt1 = New Table( "Test", Add Rows( 6 ),
	New Column( "X", Numeric, "Continuous", Format( "Best", 12 ),
		Set Values( [1, 2, 3, 1, 2, 4] ) ),
	New Column( "Y", Numeric, "Continuous", Format( "Best", 12 ),
		Set Values( [3, 2, 5, 6, 4, 3] ) ),
	New Column( "XY Group", Character, "Nominal", Set Selected, 
		Set Values( {"A", "A", "A", "B", "B", "B"} ) )
);

sc = dt1 << get selected Columns;
scn = Column(sc[1]) << get name;	// sc is a list - get the first highlighted column

Show(sc);
Show(scn);

obj = dt1 << Fit Curve(
	Y(:Y),
	X(:X),
	Fit linear,
	by (column(dt1, scn))
);