Hey Frank, Right. So I tried this loop / recur, and it runs, giving a result of *([4 nil] [3 3] [2 nil] [1 1])*. But I'm not sure how that's going to help you (although not discounting the possibility).
You can simultaneously iterate through pairs of lists, to compare values. However you cannot guarantee that those lists will be *i)* ordered, and *ii)* the same length. Both those conditions are required for your algorithm to work. Plus, what you suggest still means that you'll have to scan through the entire space of both results. So we're not going to avoid that. Based on your requirements, I still see my original *for* comprehension as the most straightforward way to solve the problem. My second suggested algorithm could also work. But I could be wrong and am always learning too. So trying different solutions is a good habit to keep. Hth Tim Washington Interruptsoftware.com <http://interruptsoftware.com> On Mon, Mar 10, 2014 at 4:53 AM, Frank Behrens <fbehr...@gmail.com> wrote: > Hey, just to share, I came up with this code, which seem quite ok to me, > Feels like I already understand something, do i, > Have a nice day, Frank > > (loop > [a '(1 2 3 4) > b '(1 3) > out ()] > (cond > (and (empty? a)(empty? b)) out > (empty? a) (recur a (rest b) (conj out [nil (first > b)])) > (empty? b) (recur (rest a) b (conj out [(first a) > nil])) > :else (let > [fa (first a) > fb (first b) > cmp (compare fa fb)] > (cond > (= 0 cmp) (recur (rest a) (rest b) (conj out [fa fb])) > (> 0 cmp) (recur (rest a) b (conj out [fa nil])) > :else (recur a (rest b) (conj out [nil fb])))))) > > > Am Montag, 10. März 2014 09:26:14 UTC+1 schrieb Frank Behrens: > >> Thanks for your suggestions. >> a for loop has to do 100.000 * 300.000 compares >> Storing the database table into a 300.000 element hash, would be a memory >> penalty I want to avoid. >> >> I'm quite shure that assential part of the solution is a function to >> iterate through both list at once, >> spitting out pairs of values according to compare >> >> (merge-sortedlists >> '(1 2 3) >> '( 2 4)) >> => ([1 nil] [2 2] [3 nil] [nil 4]) >> >> Seems quite doable. >> Try to implement now. >> >> Frank >> >> -- 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 unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
