"Phil Steitz" <phil.ste...@gmail.com> wrote in message news:497ee914.7010...@gmail.com... > Bill Barker wrote: >> I've been working on a SparseRealVector that implements RealVector but is >> backed by OpenIntToDoubleHashMap. Unlike SparseRealMatrix, the goal is >> more speed than space. Mostly it is going well, but running into a few >> problems where some RealVector methods are almost nonsensical for sparse >> vectors (e.g. mapInvToSelf). >> >> Since the default value of OpenIntToDoubleHashMap is final, this means >> that I currently have to replace the map in this case (so it really isn't >> 'self' afterwards). So what i'm asking is if it is better to have the >> default value mutable or to allow the backing to be replaced in a >> "*ToSelf" method. >> >> > I don't understand the question. Is it that different *ToSelf methods > require different missingEntries values? I don't follow how that could be > the case. In any case, the question has me thinking that at least > OpenIntToDoubleHashMap should expose a getter for missingEntries. I agree > with Luc though that this field should not be mutable. >
Well, to preserve sparseness, mapInvToSelf (x -> 1/x) should be infinity, mapLogToSelf should be -infinity, mapCosToSelf should be 1, etc. However, the more I think about it, preserving sparseness is looking like more trouble than it is worth to support methods that don't make sense if you are using a sparse vector in the first place. I'll probably just cause the vector to become dense for these methods. I'm +1 for OpenInToDoubleHashMap exposing a getter for missingEntries, but it doesn't look like my class will have a use case for it. > Phil >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org >> For additional commands, e-mail: dev-h...@commons.apache.org >> >> --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
