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 ```Did you know about hmatrix (available on Hackage) before you wrote this? "[email protected]" <[email protected]> writes: > Hi Cafe, > > I've created a numpy equivalent for Haskell. (Numpy is a python > library for multi-dimensional arrays and operations on them) > > Code at http://github.com/yairchu/numkell > (not yet on hackage because it needs better names) > > A numkell array is a pair of a function from integer inputs and a > range for its inputs (size). > This allows for easy memoizing into in-memory arrays, and > additionally, numkell arrays also support useful operations like > numpy's newaxis and folding axes away. > As the "Array" name was already taken, numkell's array is currently > called "Funk" (name suggestions very appreciated). > > An example: > Given an bunch of vectors as a 2d array, compute the distance between > each pair of vectors > > {-# LANGUAGE DeriveDataTypeable, GeneralizedNewtypeDeriving, > TypeOperators #-} > > import Data.HList > import Data.NumKell > import Data.Typeable > > newtype PersonIdx = PersonIdx Int > deriving (Enum, Eq, Integral, Num, Ord, Real, Show, Typeable) > > newtype FeatureIdx = FeatureIdx Int > deriving (Enum, Eq, Integral, Num, Ord, Real, Show, Typeable) > > let personProps = fFromList [[5,3,2],[4,8,1],[2,6,9],[5,3,0]] :: Funk > (HJust PersonIdx :*: HJust FeatureIdx :*: HNil) Double > >> personProps > FeatureIdx 0 1 2 > PersonIdx + - - - > 0 | 5.0 3.0 2.0 > 1 | 4.0 8.0 1.0 > 2 | 2.0 6.0 9.0 > 3 | 5.0 3.0 0.0 > >> sumAxes (fmap (** 2) (liftF2 (-) (personProps !/ (SNewAxis .*. HNil)) >> (personProps !/ (SAll .*. SNewAxis .*. HNil)))) (TFalse .*. TFalse .*. TTrue >> .*. HNil) > > PersonIdx 0 1 2 3 > PersonIdx + - - - - > 0 | 0.0 27.0 67.0 4.0 > 1 | 27.0 0.0 72.0 27.0 > 2 | 67.0 72.0 0.0 99.0 > 3 | 4.0 27.0 99.0 0.0 > > In Python the last line looks shorter: > >>>> ((personProps[newaxis] - personProps[:,newAxis]) ** 2).sum(2) > > Mostly due to Python's slicing syntax sugar. > Still, numkell has one large benefit over numpy (apart from being for > Haskell): With numpy this example creates a temporary 3d array in > memory. In numkell the array is not allocated in memory unless "fMemo" > is called. > > If anyone has comments, suggestions, naming suggestions, complaints, > etc, I would very much like to hear. > > cheers, > Yair > _______________________________________________ > Haskell-Cafe mailing list > [email protected] > http://www.haskell.org/mailman/listinfo/haskell-cafe -- Ivan Lazar Miljenovic [email protected] IvanMiljenovic.wordpress.com _______________________________________________ Haskell-Cafe mailing list [email protected] http://www.haskell.org/mailman/listinfo/haskell-cafe ```