[CHANGESET]: Re: scatter - markersize

[Michael Goffioul]

For you information, I'm currently working on providing the
building blocks for hggroup (listeners, dynamic properties,
hggroup object...). I'm quite busy these days, but I hope
to get something working in a week or two.

Michael.


On Wed, Mar 19, 2008 at 6:10 PM, John W. Eaton <jwe at bevo.che.wisc.edu> wrote:
>
> On 19-Mar-2008, David Bateman wrote:
>
>  | David Bateman wrote:
>  | > Christoph Keller wrote:
>  | >
>  | >> in my opinion, scatter(X,Y,S) places the scatter-marks constant in size, even
>  | >> if a "weigth"-vector S is given as an argument of scatter.
>  | >>
>  | >> In __scatter__.m I found:
>  | >>
>  | >>   h = patch("faces", [1:length(x)].', "vertices", [x, y, z], "facecolor",
>  | >>          "none", "edgecolor", "flat", "cdata", c, "marker", marker,
>  | >>          "markersize", s, "linestyle", "none");
>  | >>
>  | >> where 's' is a scalar rather than a vector. Is this by design or by
>  | >> accident?
>  | >>
>  | >> thank you for your comments, sincerely
>  | >> Christoph Keller
>  | >> (octave 3.0.0, Windows XP)
>  | >>
>  | >>
>  | >
>  | > The calculation of "s" in __scatter__.m is
>  | >
>  | > <quote>
>  | >   if (istart < nargin && firstnonnumeric > istart)
>  | >     s = varargin{istart};
>  | >     if (isempty (s))
>  | >       s = 8;
>  | >     endif
>  | >   else
>  | >     s = 8;
>  | >   endif
>  | >   ## Note markersize is in points^2 for 2D and points for 3D, and
>  | >   ## the below is an approximation, that is empircally visually correct.
>  | >   if (nd == 2)
>  | >     s = sqrt (s) / 2;
>  | >   else
>  | >     s = s / 4;
>  | >   endif
>  | > </quote>
>  | >
>  | > Therefore if you pass a value for s as a vector, it is passed to patch
>  | > as a vector.. The code
>  | >
>  | >  n = 100; x = randn(n,1); y = randn(n,1); c = sqrt(x.^2 + y.^2);
>  | > scatter(x, y, 1:100, c)
>  | >
>  | > works fine for me under Octave 3.0.0 and gnuplot 4.2.3 that I'm using..
>  | > However, it appears to be broken under 3.1.x
>  | >
>  | > D.
>  | >
>  | >
>  | Here is a changeset that gets the markersize for scatter plots working
>  | again in 3.1.x. However.
>  |
>  | n = 100; x = randn(n,1); y = randn(n,1); c = sqrt(x.^2 + y.^2);
>  | scatter(x, y, 1:100, c)
>  |
>  | won't work in 3.1.x though it works in 3.0.0... The reason is that the
>  | patch objects now require that the markersize is a scalar value. This is
>  | compatible with the behavior of the Matlab patch objects. However,
>  | matlab allows vector markersizes to scatter plots, and does this by
>  | using an hggroup to form a "scattergroup" which is a group of N patch
>  | objects each with different marker sizes.
>  |
>  | I see two ways of fixing this issue
>  |
>  | 1) The right way would be to implement a scattergroup and keep the
>  | markersize as a scalar value in the patch objects. This seems to me to
>  | be a significant amount of work and I don't want to do something like
>  | that if Shai or Michael are working in the background on the graphics.
>  |
>  | 2) The hack would be to allow patch markersize to be a matrix and so
>  | keep the same behavior as Octave 3.0.0, and a visually similar behavior
>  | to matlab, but with a handle that is incompatible. I'd be happy enough
>  | to propose a patch for this if people want this to be done, but its not
>  | the right thing to do..
>
>  I applied the patch.
>
>  I'd say wait for hggroups.  If that doesn't happen before 3.1, then we
>  can go for the hack as a temporary solution.
>
>  jwe
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