the new Where?

Question

Hi,

how can I use the new Where function with lists of lists or matrices?

xs = {10, 20, 30, 50};
Where( Print(xs); xs ==10 );

xs = {[10 20], [30 50]};
Where( Print(xs); xs ==[10 20] );

simopod · Answer

Ran into the same error:

Not all sequences are the same size in access or evaluation of 'Where' , Bad Argument

This time when using the "Contains" function. The same argument works as expected when used inside the "Get Rows Where" function.

Here's a minimal example:

Names Default To Here( 1 );
dt = Open( "$SAMPLE_DATA/Big Class.jmp" );
names = {"KATIE", "JAMES"};
r1 = dt << Get Rows Where( Contains(names, :name) );
r2 = Where( Contains(names, :name) );
Show( r1, r2 );

r1 works, r2 will throw the error.

hogi · Answer

Thanks for the insights and the trick via Mask  - much faster than

Where( xs[0,1] ==10 & xs[0,2] ==20 );

... but no chance to beat Loc.

kind of surprising ...

jthi · Answer

If you were to add one more item to your list, Where will break. I cannot really understand the error message Not all sequences are the same size in access or evaluation of 'Where' , Bad Argument( Print(xs); xs == [10 20]; ), Where/*###*/(Print(xs) ; xs == [10 20]) Names Default To Here(1); xs = {[10 20], [30 50], [10 20]}; Where( Print(xs); xs == [10 20]; ); Other example in the Scripting Index seems to be closest to this, but using index 1 doesn't really work in this case. @EvanMcCorkle If you make a simple comparison like Names Default To Here(1); xs = {[10 20], [30 50], [10 20]}; mask = Repeat(Eval List({[10 20]}), N Items(xs)); xs[1] == mask[1]; you won't get back 1, you will get back [1 1] (so one for each match). You should be able to convert this to 1 using All, but Where doesn't like that either (it seems to only compare first item in the matrix?) Names Default To Here(1); xs = {[10 20], [30 20]}; Where(Show(xs == [10 20])); // [1 0] and [0 1] If you try with xs[1], it will work until you add third item (or remove one) so most likely it is comparing wrong thing Names Default To Here(1); xs = {[10 20], [30 20]}; r = Where( Show(xs[1] == [10 20]); xs[1] == [10 20]; ); Finally with a lot of trial, error and guess work this worked at least from time to time (not really sure if you want to create large matrices for a mask). This isn't what you would expect from Where() to be for this type of comparisons unless it is documented properly Names Default To Here(1); xs = {[10 20], [30 20], [10 20]}; mask = Repeat(Eval List({[10 20]}), N Items(xs)); r = Where( //show(xs, mask, xs == mask, All(xs == mask)); All(xs == mask); );

Also doing it this way seems to be slower than just using Loc() but my test might be flawed

Names Default To Here(1);testitems = 300;//xs = {[10 20], [30 20], [10 20]};xs = Repeat({[10 20]}, testitems / 3);xs = xs || Repeat({[30 20]}, testitems / 3);xs = xs || Repeat({[1 2]}, testitems / 3);xs = xs[Random Shuffle(1::testitems)];testcount = 10000;where_speed = Repeat({.}, testcount);loc_speed = Repeat({.}, testcount);matches = Repeat({.}, testcount);category = Repeat({""}, testcount);expr1 = Expr(	wait(0);		a = HP Time();	mask = Repeat(Eval List({[10 20]}), N Items(xs));	r1 = Where(All(xs == mask));	wait(0);	b = HP Time(););expr2 = Expr(	wait(0);		c = HP Time();	r2 = Loc(xs, [10 20]);	wait(0);	d = HP Time();	);For(i = 1, i <= testcount, i++,	wait(0);	If(Random Integer(1, 2) == 2,		expr2;		expr1;		cur_cat = "Loc";	,		expr1;		expr2;		cur_cat = "Where";	);		where_speed[i] = b - a;	loc_speed[i] = d - c;	category[i] = "Loc";	matches[i] = Try(All(r1 == r2), 0);		wait(0););dt = New Table("Test",	Add Rows(testcount),	New Column("Row", Numeric, Ordinal, Formula(Row())),	New Column("Locs", Numeric, Continuous, Values(loc_speed)),	New Column("Where", Numeric, Continuous, Values(where_speed)),	New Column("Matches", Numeric, Nominal, Values(matches)),	New Column("Category", Character, Nominal, Values(category)));tab = dt << Tabulate(	Show Control Panel(0),	Add Table(		Column Table(Analysis Columns(:Locs, :Where)),		Row Table(			Grouping Columns(:Category),			Statistics(Mean, Median, Std Dev, Interquartile Range)		)	));


Names Default To Here(1);
testitems = 300;
//xs = {[10 20], [30 20], [10 20]};
xs = Repeat({[10 20]}, testitems / 3);
xs = xs || Repeat({[30 20]}, testitems / 3);
xs = xs || Repeat({[1 2]}, testitems / 3);
xs = xs[Random Shuffle(1::testitems)];


testcount = 10000;

where_speed = Repeat({.}, testcount);
loc_speed = Repeat({.}, testcount);
matches = Repeat({.}, testcount);
category = Repeat({""}, testcount);


expr1 = Expr(
	wait(0);	
	a = HP Time();
	mask = Repeat(Eval List({[10 20]}), N Items(xs));
	r1 = Where(All(xs == mask));
	wait(0);
	b = HP Time();
);

expr2 = Expr(
	wait(0);

	c = HP Time();
	r2 = Loc(xs, [10 20]);
	wait(0);
	d = HP Time();	
);

For(i = 1, i <= testcount, i++,
	wait(0);
	If(Random Integer(1, 2) == 2,
		expr2;
		expr1;
		cur_cat = "Loc";
	,
		expr1;
		expr2;
		cur_cat = "Where";
	);

	where_speed[i] = b - a;
	loc_speed[i] = d - c;
	category[i] = "Loc";
	matches[i] = Try(All(r1 == r2), 0);

	wait(0);
);

dt = New Table("Test",
	Add Rows(testcount),
	New Column("Row", Numeric, Ordinal, Formula(Row())),
	New Column("Locs", Numeric, Continuous, Values(loc_speed)),
	New Column("Where", Numeric, Continuous, Values(where_speed)),
	New Column("Matches", Numeric, Nominal, Values(matches)),
	New Column("Category", Character, Nominal, Values(category))
);

tab = dt << Tabulate(
	Show Control Panel(0),
	Add Table(
		Column Table(Analysis Columns(:Locs, :Where)),
		Row Table(
			Grouping Columns(:Category),
			Statistics(Mean, Median, Std Dev, Interquartile Range)
		)
	)
);

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