step

[#1]

The step function looks useful :)

some things which I noticed:

1) Don't use string values  as yi - although it seems to be "allowed":

2) Description - add-on:
Returns the yi argument corresponding to the largest xi which satisfies xi less than or equal to the x argument

- but only: IF there is another xi that is larger than x.

3) None of the yi values must be empty.

Names Default to Here(1);
dt = Open( "$SAMPLE_DATA/Big Class.jmp" );

dt << New Column( "binning1",Character,	"Nominal",	Formula( Step( :weight, 0, "low", 90, "mid", 140, "high", 1000, "max" ) ));

dt << New Column( "binning2",Numeric,"Nominal",	Format( "Best", 9 ),Formula( Step( :weight, 0, 0, 90, 1, 140, 2 ) ));
	
dt << New Column( "binning3",Numeric,	"Nominal",	Format( "Best", 9 ),Formula( Step( :weight, 0, 0, 90, 1, 140, 2, 1000, . ) ));

dt << New Column( "binning_final",	Numeric,	"Nominal",	Format( "Best", 9 ),	Formula( Step( :weight, 0, 0, 90, 1, 140, 2, 1000, -1 ) ));

[#2]

Interesting.  Step() seems to always choose the first string option, if one is given.

Show( Step( 500, 0, 1, 90, 2, 140, 3, 1000, "max" ) );	//"max"
Show( Step( 500, 0, 1, 90, 2, 140, "high", 1000, "max" ) );	//"high"
Show( Step( 500, 0, 1, 90, "mid", 140, 3, 1000, "max" ) );	//"mid"

[#3 · Accepted solution]

I think JMP Help's Scripting Guide gives much better idea of the function than scripting index

Scripting Guide > JSL Building Blocks > Conditional Functions > Step Function