Re: [Matplotlib-users] how to make a polar plot just of a section with grid

[Friedrich R. <fri...@gm...>]

2010/10/20 Stefan Mauerberger <ste...@mn...>:
> I want to make a polar plot with grid not of the full circle but a
> section (e.g. r=[5:6], phi=[-20:30]). The result should look like this:
> http://homepages.physik.uni-muenchen.de/~Stefan.Mauerberger/example.png
> I have tried a lot and had also looked to the examples but my results
> are not satisfying. This example
> http://matplotlib.sourceforge.net/examples/axes_grid/demo_curvelinear_grid.html  seems to be highly relevant for my needs but i do not understand it at all.
>
> I tried two different ways:
> Using the option polar=True works fine but I was not able to shrink the
> plot to the section.
> Otherwise transforming the data to cartesian coordinates (e.g.
> pcolor(r*np.sin(phi),r*np.cos(phi),data) ) the data are plotted into a
> box. But in this case I do not know how to draw a grid.

I believe only option (2) will be feasible, I remember a discussion in
past about this to having had the same outcome.

Try here: http://matplotlib.sourceforge.net/api/axes_api.html#matplotlib.axes.Axes.pcolor
(*faceted* option).

Notice the next functions on that page, they might help you saving
time, but some of them *might* not work in polar Axes, I'm not sure
which of them if any at all, just be warned.

Make sure you're using 1:1 aspect of the axes containing the pcolor()
Collection, or it will look distorted.

Friedrich

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