If []IO is 1 your APL expression expands each row, not each column, it inserts columns of 0s
On Fri, 19 May 2006, Dan Bron wrote: > I don't have access to the paper, but assuming: > > BV is a boolean vector > Z is a rank 2 array > \ is the scan/expand symbol > []IO is 1 > > Then the expression BV \[2] Z expands Z. That is, it inserts a fill row > (all spaces) in Z at each 0 in BV. The mnemonic is \ (expand) is "the > opposite" of / (compress). Similarly, in J, the equivalent is: > > BV #^:_1 Z > > 1 0 1 #^:_1 >;:'Howdy pardner' > Howdy > > pardner > > another option is: > > BV (#~ ] (1 j.#);._1~ 1: 0} ])~ Z > > 1 0 1 (#~ ] (1 j.#);._1~ 1: 0} ])~ > ;:'Howdy pardner' > Howdy > > pardner > > I'm not really sure when it's better to use #^:_1 with a boolean LHA vs # > with a complex LHA. > > -Dan > > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
