To second Bert Gunter: you may get better answers if you give us a complete
description.

On Thu, Jul 5, 2012 at 12:37 PM, Thomas C. <thomas.csapak@gmail.com> wrote:

> i have number of triangles which i'd like to store in a list,
> matrix,...etc.
> i thought it could look sth. like that:
>
> triangle        node1            node2            node3   .....
>      1               c(x1,y1)         c(x2,y3)          c(x3,y3)
>      1               c(x4,y4)         c(x5,y5)          c(x6,y6)
>

You already indicate that that's not the whole truth, but if it was you
could consider one of two approaches:
* Rather than a 2D array (also called "matrix") use a 3D array, with
dimensions n.triangle x 3 x 2.
* You could use a n.triangle x 3 matrix of complex numbers.  That may look
like a sneaky trick to put a vector into a matrix element, but some
operations of planar geometry can written elegantly.  E.g., distance
between a and b is abs(a-b).

It all depends on what you want to do.  BTW, what do you consider a
neighbor of a triangle?
*
*
If you are working with a triangle mesh, it might be better to hold the
vertices in a double matrix (n.vertex x 2) and represent the triangles as
indices into it, i.e., as an integer matrix (n.triangle x 3).  You may use
more columns in either matrix to represent more attributes.  If you find
out you need columns of different types, consider a data frame.

/Christian

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