But the question is, does it solve your problem? Your original message said that you were doing something _like_ binning, but that it wasn't. This actually _is_ binning. Is it good enough, or do you need something else?
Thanks, Cem Karan On 4/16/08 12:25 PM, "John Stiles" <[EMAIL PROTECTED]> wrote: > I never thought of using a hash function to do binning. Interesting > approach. > > > Army Research Lab wrote: >> Have you looked at hash_multimap >> (http://www.sgi.com/tech/stl/hash_multimap.html)? Note that the following >> code was beaten out in entourage, without compiling, testing, etc. >> >> struct eqdouble >> { >> bool operator()(const double d1, const double d2) const >> { >> double diff = d1 - d2; >> if (diff < 0.0) >> diff = -diff; >> return diff < 0.00001; // Or whatever other epsilon you want. >> } >> }; >> >> struct hashfunc >> { >> // This operator hashes numbers into bins of differing ranges. >> // If all your bins are the same size, use divide. >> size_t operator()(const double &d) const >> { >> if (d < 1.0) >> return 1.0; >> if (d < 3.0) >> return 2.0; >> if (d < 35.0987) >> return 3.0; >> return 4.0; >> } >> }; >> >> typedef hash_multimap<double, double, hashfunc, eqdouble> map_type; >> >> void lookup(const map_type& Map, const double d) >> { >> cout << d << ": "; >> pair<map_type::const_iterator, map_type::const_iterator> p = >> Map.equal_range(d); >> for (map_type::const_iterator i = p.first; i != p.second; ++i) >> cout << (*i).second << " "; >> cout << endl; >> } >> >> int main() >> { >> map_type M; >> M.insert(map_type::value_type(1.0, 1.0)); >> M.insert(map_type::value_type(2.0, 2.0)); >> M.insert(map_type::value_type(2.0, 12.0)); >> M.insert(map_type::value_type(2.0, 13.0)); >> M.insert(map_type::value_type(3.0, 16.0)); >> M.insert(map_type::value_type(35.0, 17.0)); >> M.insert(map_type::value_type(-56.9, 18.0)); >> M.insert(map_type::value_type(42.0, 127.0)); >> >> lookup(M, 1.0); >> lookup(M, 2.0); >> lookup(M, 35.0); >> } _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [EMAIL PROTECTED]
