That makes them each different, but if you put them in a set together, like
#{[1 2] [2 1]}, the hash of the set is 1-1=0 no matter what order those
vectors are put into the set.That is the difficulty. On Wed, Oct 23, 2013 at 10:39 AM, Pablo Nussembaum <bau...@gmail.com> wrote: > What do you think of adding odd elements and substract even ones? > > [1 2] = 1 - 2 = -1 > [2 1] = 2 - 1 = 1 > > > On 10/23/2013 02:30 PM, Andy Fingerhut wrote: > > If you can think of a different hash function for vectors that doesn't > lead to these types of collisions, I'm all ears. The issue is that the > hash function for sets adds up the hash values of its elements. Those sums > of vector hash values are what are colliding, not the individual vector > hash values themselves. > > Andy > > > On Wed, Oct 23, 2013 at 10:28 AM, Paul Butcher <p...@paulbutcher.com>wrote: > >> On 23 Oct 2013, at 18:15, Andy Fingerhut <andy.finger...@gmail.com> >> wrote: >> >> If we had a 'universal comparator', i.e. a comparison function that >> provided a total order on any pair of values that anyone would ever want to >> put into a set or use as a map key, then instead of having linked lists for >> values that collide, we could have trees like those in the implementations >> of sorted-maps and sorted-sets today. >> >> >> Wouldn't it be better to improve the way that hashes are calculated for >> vectors? A good hash function should make it unlikely that similar values >> have the same hash. The current algorithm seems to make that more likely >> than it should? >> >> -- >> paul.butcher->msgCount++ >> >> Snetterton, Castle Combe, Cadwell Park... >> Who says I have a one track mind? >> >> http://www.paulbutcher.com/ >> LinkedIn: http://www.linkedin.com/in/paulbutcher >> MSN: p...@paulbutcher.com >> AIM: paulrabutcher >> Skype: paulrabutcher >> >> -- >> -- >> 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. >> > > -- > -- > 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. > > > -- > -- > 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. > -- -- 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.
