Column switcher & try function

Question

Hi,

Is it possible to use the try function in a column switcher script? I´m creating a script where I add a column switcher fore a few chosen columns to a graph which works fine. However, sometimes a column will be missing which will make the script stop. Therefore, I´m trying to use the try function for each of the relevant columns (as I don´t want all columns in the column switcher) but I can´t make it work.

dt << Column Switcher(
	Try( (:RER), Throw( "RER does not exist" ) ),
	Try( (:VO2), Throw( "VO2 does not exist" ) ),
	Try( :Name( "Drink-[ml]" ), Throw( "Drink-[ml] does not exist" ) )
);

Is it possible or is there a better way to do this?

Br Julie

Mark_Bailey · Answer

I would use the Try() function outside of the message. Build the message conditionally. Like this:

Names Default to Here( 1 );

dt = Open( "$SAMPLE_DATA/Fitness.jmp" );

gb = dt << Graph Builder(
	Size( 532, 456 ),
	Show Control Panel( 0 ),
	Show Legend( 0 ),
	Variables( X( :Age ), Y( :Oxy ) ),
	Elements( Points( X, Y, Legend( 3 ) ) )
);

alt cols = List();
Try(
	Insert Into( alt cols, Column( dt, "Age" ) )
);
Try(
	Insert Into( alt cols, Column( dt, "Weight" ) )
);
Try(
	Insert Into( alt cols, Column( dt, "Runtime" ) )
);

col switcher expr = Expr( Column Switcher( :age ) );
Insert Into( col switcher expr, alt cols );

Eval(
	Insert(
		Expr( Send( gb ) ),
		Name Expr( col switcher expr )
	)
);

txnelson · Answer

Here is how I would do it Names Default To Here( 1 ); dt = Open( "$SAMPLE_DATA/big class.jmp" ); // set desired list of columns to be in column switcher desiredColList = {"Height", "Weight", "Zippy"}; // remove from list, columns that are not available For( i = N Items( desiredColList ), i >= 1, i--, If( Try( Column( dt, desiredColList[i] ) << get name, "" ) == "", Remove From( desiredColList, i, 1 ) ) ); // If columns are available, run the platform If( N Items( desiredColList ) > 0, ow = oneway( x( :age ), y( :height ) ); ow << Column Switcher( :height, desiredColList ); );