Re: [igraph] R igraph 1.0 and return.vs.es

[Gábor Csárdi]

On Fri, Jun 26, 2015 at 10:05 PM, Dr Gregory Jefferis
<address@hidden> wrote:
> One thing I have noticed is that some of my functions (in CRAN package nat)
> now run ~50x slower. I've traced this to a change in behaviour, where
> functions like graph.dfs return vertex sequences rather than plain (integer)
> vertex ids. subsetting those vertex sequences can be very slow. This can be
> changed by the igraph_option return.vs.es=F (which incidentally does not
> seem to be documented)

Undocumented, because it is dangerous. If you change it, it'll apply
globally. I think if you change it now, you are probably safe, though,
because most functions expect numbers instead of vertices.

> Here is a (stupid) toy example:
[...]
>    user  system elapsed
>   0.713   0.007   0.719
[...]
>   0.001   0.000   0.001
[...]

> But this means changing quite a bit of code and there are places where
> similar issues cannot be so easily side-stepped.
>
> Two questions:
>
> 1. Is this slow down expected?

Wow, I expected it to be slower, but not this much. I should have measured.

> 2. As a package developer, is there any way to ensure I have the behaviour
> of igraph_options(return.vs.es=F) when I import the igraph package (while
> still giving other users the chance to set  igraph_options(return.vs.es=T)
> if that is what they want) ?

Unfortunately not, AFAIK. These options are global.

> As a comment, my feeling is that this behaviour should probably be
> controlled both at a per function as well as a package option level.

Yes, function specific arguments are good.

You can set the option as a workaround now, I think. I'll speed this
up in 1-2 weeks, and then everything should be fine again.
G.

[...]