Can you construct this without writing expression as a string?

ih

I dislike constructing jsl expressions as strings, it makes them hard to troubleshoot and checking for syntax errors is a multistep process. This example solution for @A_Zaid's Plotting conditionally post has me struggling though.  Is it possible to construct this graph builder function without writing the string and parsing it as text? I'm stuck when trying to construct the 'expression' of Y arguments which is an unknown number of arguments and can't be parsed on its own.

 

Maybe there an equivalent to do.call, invoke, or exec operators in R, or the splat operator in Python that I haven't found yet?

 

Names default to here(1);

dt = Open("$Sample_data/probe.jmp");

//Variables to hold the dynamic parts of the graph builder expresssion
Expr1 = "";
Expr2 = "";

// Pick columns to include
cols = ( dt << get column names() )[random shuffle(8::397)[1::5]];

//Populate expressions
for(c=1, c<= n items(cols), c++,
	Expr1 = Expr1 || "Y( Column( \!"" || cols[c] || "\!" ), Position(1) ),";
	Expr2 = Expr2 || "Y( " || char( c ) || " ),";
);

Eval( Parse( substitute(
	//the graph builder script as a string with 'dummy variables' where the
	//expressions created earlier will go
	"gb = Graph Builder(
		Size( 838, 391 ),
		Variables(
			X( :DELL_RPPBR ),
			Expr1_
		),
		Elements( Line( X, Expr2_ Legend( 10 ) ) ),
		Local Data Filter(
			Add Filter(
				columns( :DELL_RPPBR ),
				Where( :DELL_RPPBR >= -1 & :DELL_RPPBR <= 0.483837991952896 )
			)
		)
	)",
	//replace the 'dummy variables'
	"Expr1_",
	Expr1,
	"Expr2_",
	Expr2
) ) );

 

jthi

I usually just fall back to using Eval(Parse()) because it feels way easier. Found this Re: Use variable list of columns as Y Axis in Graph Builder where @Mark_Bailey gives solution to something similar.

 

Here is my attempt with this:

Names Default To Here(1);

dt = Open("$Sample_data/probe.jmp");

cols = (dt << get column names())[Random Shuffle(8 :: 397)[1 :: 5]];

var expr = Expr(
	Variables(X(:DELL_RPPBR))
);

var line = Expr(Line(X));

For(c = 1, c <= N Items(cols), c++,
	y expr = Expr(Y(Position(1)));
	Insert Into(y expr, cols[c], 1);
	Insert Into(var expr, Name Expr(y expr));
	
	yline expr = Parse("Y("||char(c)||")");
	Insert Into(var line, Name Expr(yline expr));

);

yline expr = Expr(Legend(10));
Insert Into(var line, Name Expr(yline expr));

Eval(
	Substitute(
			Expr(
				gb = dt << Graph Builder(
					Size(838, 391),
					Show Control Panel(0),
					vvv,
					Elements(yyy),
					Local Data Filter(Conditional, Add Filter(columns(:DELL_RPPBR), 
						Where(:DELL_RPPBR >= -1 & :DELL_RPPBR <= 0.483837991952896)))
				)
			),
		Expr(vvv), Name Expr(var expr),
		Expr(yyy), Name Expr(var line)
	)
);

I thought that this wouldn't help at all with debugging but it does because you can just run the Substitute() part of graph builder generation to see what it tries to do (and you also get JSL syntax highlighting).