J prefers that the "initial value" be equivalent to the "identity value" for your operation, and gives a significant performance boost to your code if you can express it in those terms.
That said, yes, you can express things using an arbitrary initial value. for example: arbred=:1 :0 : > u&.>/(<"_1 y),<x ) 0 0 +arbred 1 2 3 6 6 I hope this helps. -- Raul On Mon, Jun 22, 2015 at 9:53 PM, Marshall Bockrath-Vandegrift <[email protected]> wrote: > Hi all, > > I'm still in the process of learning J, and trying to adapt ideas from > other languages. In many (other?) functional programming languages it is > possible to reduce over a collection starting with a provided initial value > which does not belong to the reduced collection. To attempt to put this in > J terms, such an operation would allow the initial value and result of each > reduction step to have a different shape than that of the the items of the > value being reduced. As far as I can tell, the standard `/` adverb provides > no such facility. Is there a J idiom for this? > > Thanks, > > -Marshall > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
