On Thu, Aug 19, 2010 at 7:56 PM, Glen Rubin <rubing...@gmail.com> wrote: > > I want to multiply a list of n items by h lists of n items, so that > for example if i have list 'a' and 'b' > > (def a (list 1 2 3)) > (def b (list '(4 5 6) '(7 8 9))) > > when multiplied I will get: > > ((4 10 18) (7 16 27)) >
Others have already given this solution, but I'd like to generalize it. Tomorrow you might need to add those two lists in that way, or do some other similar thing: (defn mapmap [f a b] (map #(map f a %) b)) (def m* (partial mapmap *)) (def m+ (partial mapmap +)) (def m- (partial mapmap -)) (def mdiv (partial mapmap /)) user> (m+ '(1 2 3) '((4 5 6) (7 8 9))) ((5 7 9) (8 10 12)) user> (m- '(1 2 3) '((4 5 6) (7 8 9))) ((-3 -3 -3) (-6 -6 -6)) user> (m* '(1 2 3) '((4 5 6) (7 8 9))) ((4 10 18) (7 16 27)) user> (mdiv '(1 2 3) '((4 5 6) (7 8 9))) ((1/4 2/5 1/2) (1/7 1/4 1/3)) The key to this is that clojure allows us to pass around functions, so called higher order functions, and allows us to very easily generalize operations. -- http://www.apgwoz.com -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
