It works great with patches of circles. Thank you.
Also, I want my circles to look round, so I use the command
axis('equal'). Is there any way to make sure that the area I defined
with xlim() and ylim() won't be cut off. I'd rather have one dimension
expanded than the other one shrunk. Can I control that?
thanks,
guillaume
Le 07/09/2010 18:05, Benjamin Root a écrit :
2010/9/7 Guillaume Chérel <guillaume.c.che...@gmail.com
<mailto:guillaume.c.che...@gmail.com>>
Hello,
I'm trying to draw circles with the scatter function. They are
supposed
to represent trees in the savannah. It is thus important that they are
displayed with a proper size, that is, one which represents their
actual
size on the field. After quite some confusion, I've found out (I
think)
that the size argument one can specify with the scatter function is
given as a disk's surface in pixels square (I think that's what means
the "points^2" in the documentation and from my own tests)
What I would like is to give a surface in unit^2, where "unit" is the
unit of my data, and which you can read on the plot's axes ticks. For
example, each tree has coordinates like x=3500, y=2210. (The unit here
is centimeters but we don't really need to know this). Say I want to
draw a tree which canopy is 200 cm wide. That makes a disk which
radius
is 100, or surface 100^2*PI. How can I draw this?
Many thanks,
Guillaume
Guillaume,
Using scatter is probably not the way to go about what you want. The
circles for scatter are a fixed size and if you zoom in, they will not
scale accordingly.
You probably want to create patches of Circles:
http://matplotlib.sourceforge.net/api/artist_api.html#matplotlib.patches.Circle
http://www.mail-archive.com/matplotlib-users@lists.sourceforge.net/msg06786.html
Or even utilize a collection of Circles:
http://matplotlib.sourceforge.net/api/collections_api.html#matplotlib.collections.CircleCollection
Note that for a CircleCollection, you would use 'offset' to indicate
the center of each circle. After creating the collection, you would
then use ax.add_collection() function to add that collection to the axes.
I hope that is helpful.
Ben Root
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