On Wed, Oct 28, 2009 at 9:06 AM, Eero Nevalainen
<eero.nevalai...@indagon.com> wrote:
> Hi,
>
> I need to draw error ellipses on a scatterplot. I'm guessing someone has
> done this before.
>
> I've found some examples, such as this one
> http://matplotlib.sourceforge.net/examples/pylab_examples/ellipse_rotated.html
>
> That led to the artist tutorial, and... ARGH! INFORMATION OVERFLOW!
>
> Can someone explain to me, why I suddenly have to know so much about
> matplotlib's internals to get an ellipse drawn?
Hi,
I just made a function to draw uncertainty ellipses defined by a
covariance matrix P:
def plotEllipse(pos,P,edge,face):
U, s , Vh = svd(P)
orient = math.atan2(U[1,0],U[0,0])
ellipsePlot = Ellipse(xy=pos, width=math.sqrt(s[0]),
height=math.sqrt(s[1]), angle=orient,facecolor=face, edgecolor=edge)
ax = gca()
ax.add_patch(ellipsePlot);
show()
return ellipsePlot
To use it: ellipsePlot=plotEllipse([x,y],P,'black','0.3')
Hope this helps,
Tinne
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