Hi,Gaarth.
Thank you for helpful advice.
On 2ζ13ζ₯, εεΎ1:03, Garth Sheldon-Coulson <g...@mit.edu> wrote:
> I have confronted a similar question in the past when deciding how to label
> the dimensions of vectors and multidimensional arrays.
>
> My tentative conclusion is that it's best to use raw vectors.
>
> => (def v [40 41 42])
> #'user/v
>
> If you need human-readable labels, build a separate index with constant
> lookup.
>
> => (def vindex {:x 0 :y 1 :z 2})
> #'user/vindex
> => (v (:z vindex))
> 42
>
> You can put v and vindex in a single hashmap or class or type or whatever.
>
> There are all kinds of reasons for this. The main one is that your data
> proper remains in a pure array-like data structure and can easily be
> processed by high-performance algorithms for things like array slicing and
> transposition, not to mention mathematical routines. The fact that you're
> putting human-readable names on your indices is just a convenience.
>
> Moreover, every time you want to get a sequence of elements out of your
> vector, you don't want to have to loop through the hashmap pulling the
> elements out in the right order. Mathematical vectors are orderful things
> and should be represented in an orderful data structure. Clojure vectors are
> ordered. Hashmaps are unordered.
>
> That's the conclusion I have come to, at any rate.
>
> Garth
>
>
>
> On Fri, Feb 12, 2010 at 10:36 PM, Hozumi <fat...@googlemail.com> wrote:
> > Hi,all
> > Although there is no right answer, vector seem to be preferred in many
> > cases.
> > Which do you prefer map or vector?
> > Thanks!
>
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