[RQt-devel] performance of Qt's bsp tree

[Michael Lawrence]

How much memory is being consumed? Calling ensureIndex() didn't cause a
problem on my laptop, which just has 2GB of memory. Is ensureIndex() now
fast for you? I'd be surprised if the query itself consumed a lot of memory.

Thanks,
Michael

On Sat, Apr 9, 2011 at 8:18 PM, Yihui Xie <xieyihui at gmail.com> wrote:

> Sounds great. Thanks! It seems it's still difficult to get around the
> memory issue: it is almost impossible to index 1 million points on my
> laptop (R will not respond for several minutes if I try to brush the
> points).
>
> Regards,
> Yihui
> --
> Yihui Xie <xieyihui at gmail.com>
> Phone: 515-294-2465 Web: http://yihui.name
> Department of Statistics, Iowa State University
> 2215 Snedecor Hall, Ames, IA
>
>
>
> On Fri, Apr 8, 2011 at 7:47 AM, Michael Lawrence
> <lawrence.michael at gene.com> wrote:
> > Just a follow-up to some some concerns from the cranvas group about the
> poor
> > performance of the BSP indexing of QGraphicsScene. It looks like the
> index
> > was pretty much rewritten between Qt 4.5 (what I showed at DSC 09) and Qt
> > 4.6. In fact, it was being rewritten during the DSC. This has resulted in
> > apparently much poorer performance. It now takes 4-5 seconds to index
> only
> > 100,000 points. Don't even think about indexing a million.
> >
> > Whatever they changed, it's now really slow to add a point one at a time
> to
> > the index. I think they might be sorting something each time. They're
> using
> > quick sort, but a binary tree would be a better idea for efficient
> updating.
> > Thus, I changed qtpaint to disable the index while populating the scene
> and
> > then re-enable the index after all objects have been added. This is
> > considerably faster. Now 100,000 points take 0.2 seconds and a million
> takes
> > 2 seconds. Nice and linear. Not as fast as before though, because there
> is
> > still a sort.
> >
> > Michael
> >
> >
> >
> > _______________________________________________
> > Qtinterfaces-devel mailing list
> > Qtinterfaces-devel at lists.r-forge.r-project.org
> >
> https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/qtinterfaces-devel
> >
> >
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.r-forge.r-project.org/pipermail/qtinterfaces-devel/attachments/20110409/4727658b/attachment.htm>