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Re: fast scatter plots - advice sought
From: |
Jaroslav Hajek |
Subject: |
Re: fast scatter plots - advice sought |
Date: |
Mon, 11 Jan 2010 08:22:03 +0100 |
On Mon, Jan 11, 2010 at 8:17 AM, David Bateman <address@hidden> wrote:
> Jaroslav Hajek wrote:
>>
>> hi,
>>
>> I recently started some work where I'm going to use scatter plots
>> heavily with a few thousand points.
>> I found out, however, that scatter plots were unusably slow with so
>> many points. This has also been reported before:
>>
>> http://old.nabble.com/scatter3-is-really-slow-to24312164.htm
>>
>> by this changeset
>> http://hg.savannah.gnu.org/hgweb/octave/rev/2f435ed48143
>>
>> I tried to optimize the plotting strategy to get more reasonable
>> times, especially in the simplest cases. The old strategy of creating
>> one object per point is only used for small numbers of points (<= 20).
>> Otherwise, the points are split into subsets with common color and
>> size, and these subsets are plotted using a single primitive. This
>> seems similar to what Matlab does.
>>
>
> If this is done in the baackend ok, but I deliberately didn't make this
> change in the frontend as it breaks matlab compatibility
>
What breaks Matlab compatibility? Please explain. Note that it is
*not* true that Matlab always creates one object per point (as you
seemed to imply in the above linked mail), at least in 2007a. It does
so only when there is a small number of points:
>> n = 10;
>> h = scatter (rand (n, 1), rand (n, 1))
h =
159.0022
>> get(h,'children')
ans =
169.0011
168.0011
167.0011
166.0011
165.0011
164.0011
163.0011
162.0011
161.0015
160.0012
>> n = 1000;
>> h = scatter (rand (n, 1), rand (n, 1))
h =
159.0028
>> get(h,'children')
ans =
160.0013
I bet the strategy Matlab uses is similar to ours. I didn't
investigate the switch point, but I don't really think compatibility
is needed at that level.
regards
--
RNDr. Jaroslav Hajek, PhD
computing expert & GNU Octave developer
Aeronautical Research and Test Institute (VZLU)
Prague, Czech Republic
url: www.highegg.matfyz.cz
- fast scatter plots - advice sought, Jaroslav Hajek, 2010/01/10
- Re: fast scatter plots - advice sought, Shai Ayal, 2010/01/10
- Re: fast scatter plots - advice sought, David Bateman, 2010/01/11
- Re: fast scatter plots - advice sought,
Jaroslav Hajek <=
- Re: fast scatter plots - advice sought, Michael Goffioul, 2010/01/11
- Re: fast scatter plots - advice sought, Kai Habel, 2010/01/11
- Re: fast scatter plots - advice sought, Robert T. Short, 2010/01/11
- Re: fast scatter plots - advice sought, John W. Eaton, 2010/01/11
- Re: fast scatter plots - advice sought, Jaroslav Hajek, 2010/01/11
- Re: fast scatter plots - advice sought, John W. Eaton, 2010/01/11
- Re: fast scatter plots - advice sought, David Bateman, 2010/01/11
- Re: fast scatter plots - advice sought, David Bateman, 2010/01/11
- Re: fast scatter plots - advice sought, Michael D Godfrey, 2010/01/11
- Re: fast scatter plots - advice sought, John W. Eaton, 2010/01/11