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f;.n Sparse Arguments |
initial writing: 2000-12-08 |
The dyad x f;.n y now has special code for sparse boolean vector x . For example:
ts=: 6!:2 , 7!:2@] f0=: {. ; }. 2-cut case f1=: 4 : '(1 (0,x.)}1$.(#y.);0;0) <;.1 y.' sparse left argument to cut f2=: 4 : '(1 (0,x.)}(#y.)$0) <;.1 y.' dense left argument to cut x=: 1e5 y=: i.1e6 x (f0 -: f1) y 1 x (f1 -: f2) y 1 ts 'x f0 y' 0.028419 4.72e6 ts 'x f1 y' 0.0288414 4.72653e6 ts 'x f2 y' 0.0480949 6.82246e6 p=: ?.20$#y p (f1 -: f2) y 1 ts 'p f1 y' 0.0385063 5.95846e6 ts 'p f2 y' 0.0635578 8.05395e6