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Re: [igraph] why use floating point for graph nodes?

From: Szabolcs Horvát
Subject: Re: [igraph] why use floating point for graph nodes?
Date: Thu, 5 Nov 2015 10:48:02 +0100

On 5 November 2015 at 10:17, Gábor Csárdi <address@hidden> wrote:
> so that you don't need to copy between C and R.

Oh, so does the R interface avoid copying data structures that are
also exposed to R?  (I don't know anything about R internals or how to
extend R with C.)

In which situations does it manage to avoid copies?  I am interested
in this because a major bottleneck of the Mathematica interface is all
the copying it needs to do and currently I'm trying to speed things

When igraph functions return an igraph_vector_t, does it need to be
copied to get exposed as an R numerical vector?  If not, did you need
to make changes to igraph's memory allocation to make it usable in
conjunction with R?

I know that copies can be avoided when sending data *to* igraph, e.g.
often we can use igraph_vector_view()

Does igraph offer anything similar to a "vector view" for an igraph_t?
 I.e. if I already have an igraph_vector_t for the "from" vertices and
"to" vertices, can I safely re-use them inside of a graph?  I never
really looked at the internal structure and I don't know what oi, ii,
os, is do ...  If igraph wasn't designed for this, it's probably not a
good idea for me to push it though.

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