A reader macro for destructuring might be nifty, like #[...]. So you could do things like:
(#(map (partial reduce +) #[[[[a b c][d e f]]] %]) signal) Not sure if that'd be the right syntax, but you get the point. On Sat, Aug 28, 2010 at 12:08 PM, John Newman <john...@gmail.com> wrote: > Don't forget destructuring: > > (for [[a b c] signal] > (map (partial reduce +) [a b c])) > > and, > > ((fn [[[a b c][d e f]]] > (map (partial reduce +) [a b c d e f])) > signal) > > While messing around with that, I was wondering if there were some > function that allowed you to destructure on-demand. > > Like, > => (destruct [[[a b c][d e f]]] signal) > (1 2 3 4) (2 3 4 5) (3 4 5 6) (3 4 5 6) (4 5 6 7) (5 6 7 8) > > Anything like that exist? > > -- > John > > On Wed, Aug 25, 2010 at 10:36 AM, James Reeves <jree...@weavejester.com> > wrote: >> I think you're getting confused. >> >> (map reduce + %) won't work, because the signature of the map function >> is (map func & colls). In other words, the second argument is expected >> to be a collection, but you've put in +, which is a function. >> >> When dealing with nested collections, you may want to work from the >> inside out. So take one of your inner lists: >> >> s1: (1 2 3 4) >> >> (reduce + s1) => 10 >> (apply + s1) => 10 >> >> You can use reduce or apply to sum the lists. On the next level, we have: >> >> s2: ((1 2 3 4) (2 3 4 5) (3 4 5 6)) >> >> (map (partial reduce +) s2) => (10 14 18) >> >> So we're using map to sum each list. (partial reduce +) is just >> another way of writing #(reduce + %). >> >> Next is the final layer: >> >> signal: (((1 2 3 4) (2 3 4 5) (3 4 5 6)) ((3 4 5 6) (4 5 6 7) (5 6 7 8))) >> >> (map (partial map (partial reduce +)) signal) >> => ((10 14 18) (18 22 26)) >> >> Again, we add a map, and use partial. We could perhaps make this a >> little clearer by using for: >> >> (for [s signal] >> (for [c s] (reduce + c))) >> >> - James >> >> >> On 25 August 2010 15:06, Glen Rubin <rubing...@gmail.com> wrote: >>> After toying around at the REPL I realize that I have been working >>> with a heretofore invalid understanding of collections. For example, >>> working with the following collection(s): >>> >>> signal: >>> (((1 2 3 4) (2 3 4 5) (3 4 5 6)) ((3 4 5 6) (4 5 6 7) (5 6 7 8))) >>> >>> I wanted to sum each individual list: e.g. (1 2 3 4) = (10) >>> >>> I thought I could do this as follows: >>> >>> (map #(map reduce + %) signal) >>> >>> This resulted in an error, so trying to comprehend why I ran the >>> following: >>> >>> (map #(map identity (take 1 %)) signal) >>> >>> which results in, >>> (((1 2 3 4)) ((3 4 5 6))) >>> >>> So, clojure sees 'signal' as 2 collections, whereas I thought it was a >>> single collection. This makes me concerned that I have been doing >>> everything wrong thus far and getting computational errors. :( So, >>> how should I sum each individual list in the above collections? >>> >>> -- >>> 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 >> >> -- >> 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 > -- John -- 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
