Pardon, in the example above we have a 3 x 3 x 3 nested vector, not a 3 x 3 matrix!
On Jan 23, 2:45 pm, Rock <rocco.ro...@gmail.com> wrote: > I have a working function to slice multidimensional nested vectors a > la MATLAB (actually more like NumPy). > > I'm using Konrad Hinsen's multi-array library (keep up the great work > Konrad!). Here's the code (I'm sure it can be greatly improved and > optimized): > > (defn nv-subvec [x & ind] > (loop [v x > dim 0 > i ind] > (let [[start end step] (first i) > other (rest i)] > (if (empty? other) > (nv-sample v dim start end step) > (recur (nv-sample v dim start end step) (inc dim) other))))) > > It works like this: > > (nv-subvec VECTOR SLICE+) > > where each SLICE is [STAR END STEP]. > > Here's a 3 x 3 matrix: > > (def a [[[1 2 3] [4 5 6] [7 8 9]] [[10 11 12] [13 14 15] [16 17 18]] > [[19 20 21] [22 23 24] [25 26 27]]]) > > user=> (nv-subvec a [0 3 2] [0 2 1] [1 3 1]) > > [[[2 3] [5 6]] [[20 21] [23 24]]] > > user=> (nv-subvec a [0 3 2] [0 2 1]) > > [[[1 2 3] [4 5 6]] [[19 20 21] [22 23 24]]] > > The result is correct in both cases. Seems to work fine. Of course a > lot of space for improvement. > > Let me know what you think. > > On Jan 11, 8:26 am, Konrad Hinsen <konrad.hin...@fastmail.net> wrote: > > > > > On 10 Jan 2010, at 21:39, extrackc wrote: > > > > Have you looked into Incanter project? I just found out about it > > > recently. "Incanter is a Clojure-based, R-like platform for > > > statistical computing and graphics." http://incanter.org/ > > > Incanter uses ParallelColt as its underlying matrix library. While > > this is a fine library for working with matrices, it is not a > > multidimensional array library. Colt arrays exist only in 1, 2, and 3 > > dimensions and there are no generic (dimension-independent) operations > > on array structure. > > > As the huge success of Matlab has shown, a lot can be done with just > > matrices and vectors, but anyone who has used an array language (such > > as APL) or an equivalent library (such as Python's NumPy) will feel > > constrained by such an approach. > > > Konrad. -- 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
