Interesting alternatives. (vec) makes a vector out of a collection, so this is meant to be faster than (apply vector)? Also how does (into []) differ from (vec) in terms of what it does and its performance?
On Saturday, 30 November 2013 21:48:10 UTC, Kelker Ryan wrote: > > Vectors are mostly for speed and maintaining value sequence order. > > Try this => (vec (reverse [1 2 3])) > Not this => (apply vector (reverse [1 2 3])) > > As an alternative you can do this => (into [] (reverse [1 2 3])) > > You can always use mapv when calling fun for each coll object. > > Try this => (mapv #(* 2 %) [1 2 3]) > Not this => (apply vector (map (partial * 2) [1 2 3])) > > > 01.12.2013, 06:15, "Andy Smith" <the4th...@googlemail.com <javascript:>>: > > Hi, > > I am trying to understand the manipulation of vectors from an efficiency > point of view. For example if I want to reverse a vector I can do the > following > > (apply vector (reverse [1 2 3])) > > My understanding is that reverse will create a new list object (3 2 1) > then this will be used to construct a new vector object [3 2 1]. What can > I use to construct a new vector directly instead of having the intermediate > list object being constructed? > > I have read about rseq as providing something like a reverse iterator to > the same underlying vector, which may be a great solution in this case, but > my question is really about the more general case of any function that > manipulates a vector e.g. the following also returns a list rather than a > vector as desired, > > (map (partial * 2) [1 2 3]) > > again forcing me to use apply vector e.g. > > (apply vector (map (partial * 2) [1 2 3])) > > Why dont we have a version of map that returns a vector when given a > vector? We can do this kind of thing in other languages with > templates/generics why not clojure? > > There is obviously some basic principle/understanding that I am missing > here. This kind of thing surely cant be very efficient, can it? > > Andy > > > -- > -- > You received this message because you are subscribed to the Google > Groups "Clojure" group. > To post to this group, send email to clo...@googlegroups.com <javascript:> > Note that posts from new members are moderated - please be patient with > your first post. > To unsubscribe from this group, send email to > clojure+u...@googlegroups.com <javascript:> > 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+u...@googlegroups.com <javascript:>. > For more options, visit https://groups.google.com/groups/opt_out. > > -- -- 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/groups/opt_out.
