MathGroup Archive 2005

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Re: Pattern matching at bottom depth


Luc,

You could use Map with a negative level specification.

lst1 = {{0, 0, 0}, {1, 2, 3}};
lst2 = {{{0, 0, 0}, {1, 1, 1}}, {{1, 1, 1}, {2, 2, 2}, {3, 4, 3}}};

Map[transform, lst1, {-2}]
{transform[{0, 0, 0}], transform[{1, 2, 3}]}

Map[transform, lst2, {-2}]
{{transform[{0, 0, 0}], transform[{1, 1, 1}]}, {transform[{1, 1, 1}], 
    transform[{2, 2, 2}], transform[{3, 4, 3}]}}

David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/ 



From: Barthelet, Luc [mailto:lucb at ea.com]
To: mathgroup at smc.vnet.net

I have a function Foo (attribute hold) that will take 3D Points as
arguments either in a list or a list of lists.

So I can call:

Foo[{{0,0,0},{1,2,3}}]

Or

Foo[{{{0,0,0},{1,1,1}},{{1,1,1},{2,2,2},{3,4,3}}}]

Now, I would like to pattern match the triplets, so that I can run a
transformation (transform[u]) on them before releasing the hold on Foo.

Currently I do it with 2 rules and the conditional use of dimensions.

Foo [u_ /; Length[Dimensions[u]] == 2] :> Foo [transform /@ u],
Foo [u_ /; Length[Dimensions[u]] == 3] :> Foo [Map[transform, u,{2}]]

Is there a better way to do this?

Thanks

Luc





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