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
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