matplotlib-users Mailing List for matplotlib

Hi,

being a newbie myself, .. I don't know if I'm misguiding you. But do 
wonder if you looked at the scatter command
see scatter_demo2.py on
http://matplotlib.sourceforge.net/screenshots.html for an example

It *seems* like it already does what you are trying to do?, maybe I'm 
missing something in my understanding.

Steve



Andrew McLean wrote:
> I'm a new user of matplotlib (athough I have been using both Matlab and
> Python for years).
>
> I have an application where I need to display data as a set of filled
> circles. The centre and the radius of the circles are both specified in
> data coordinates. The data points have an additional scalar attribute,
> which is displayed using a pseudo-colour mapping.
>
> I've hacked something together where the circles are approximated by
> polygons using either the axis fill method or the pylab fill function. I
> select the colour by calling the get_rgba method of a ScalarMappable
> object. In the following code snippet c is a tuple containg the x and y
> coords of the centre of the circle, the radius, and a scalar "value"
>
> theta = arange(numSegs+1) * 2.0 * math.pi / numSegs
> cos_theta = cos(theta)
> sin_theta = sin(theta)
> for c in cart:
>     x = c[1] + c[3] * cos_theta
>     y = c[2] + c[3] * sin_theta
>     v = c[4]
>     fill(x, y, facecolor=mapper.to_rgba(v), linewidth=0.5)
>
> It all works. However, I saw in the API documentation (and the source)
> that there is a Circle object in patch. I was hoping that using this
> rather than polygons would give better quality output and possibly
> smaller files. Now I can instantiate it
>
>         circle = Circle((x,y), c[3], facecolor=cmapper.to_rgba(v))
>
> but can't work out what to do with it! I've tried
>
>         ax.add_patch( circle )
>
> and also
>
>         trans = blend_xy_sep_transform( ax.transAxes, ax.transData  )
>         circle.set_transform( trans )
>         ax.add_patch( circle )
>
> Neither work. Any ideas?
>
> Regards,
>
> Andrew
>
>
>
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>   

I'm a new user of matplotlib (athough I have been using both Matlab and
Python for years).

I have an application where I need to display data as a set of filled
circles. The centre and the radius of the circles are both specified in
data coordinates. The data points have an additional scalar attribute,
which is displayed using a pseudo-colour mapping.

I've hacked something together where the circles are approximated by
polygons using either the axis fill method or the pylab fill function. I
select the colour by calling the get_rgba method of a ScalarMappable
object. In the following code snippet c is a tuple containg the x and y
coords of the centre of the circle, the radius, and a scalar "value"

theta = arange(numSegs+1) * 2.0 * math.pi / numSegs
cos_theta = cos(theta)
sin_theta = sin(theta)
for c in cart:
    x = c[1] + c[3] * cos_theta
    y = c[2] + c[3] * sin_theta
    v = c[4]
    fill(x, y, facecolor=mapper.to_rgba(v), linewidth=0.5)

It all works. However, I saw in the API documentation (and the source)
that there is a Circle object in patch. I was hoping that using this
rather than polygons would give better quality output and possibly
smaller files. Now I can instantiate it

        circle = Circle((x,y), c[3], facecolor=cmapper.to_rgba(v))

but can't work out what to do with it! I've tried

        ax.add_patch( circle )

and also

        trans = blend_xy_sep_transform( ax.transAxes, ax.transData  )
        circle.set_transform( trans )
        ax.add_patch( circle )

Neither work. Any ideas?

Regards,

Andrew