Polar Plot

Hello all,

I am using matplotlib in order to generate a scientific
drawing called “Smith Chart”. It consists of many shifted circles
drawn in polar plot. This chart is widely used in electrical engineering field.

I am facing a problem now with the new version of
matplotlib. After trying around I figured out that the plot function does not
connect the given points in straight lines however by a circle or a circle
sector. This causes a very wrong drawing and producing parasitic, false, circles
when the points are to cross the theta=180° line.

I attach two images, one produced by old matplotlib and when
with the new one for demonstration. The plotting code is also attached for
reference.

Is this a new feature in the library which I can switch off
for my purpose? Or can you guide me for any help?

Thanks a lot for your effort,

Sherif

old.png

new.PNG

PlotSmith.py (8.82 KB)

Sherif Ahmed wrote:

Hello all,

I am using matplotlib in order to generate a scientific drawing called �Smith Chart�. It consists of many shifted circles drawn in polar plot. This chart is widely used in electrical engineering field.

I am facing a problem now with the new version of matplotlib. After trying around I figured out that the plot function does not connect the given points in straight lines however by a circle or a circle sector. This causes a very wrong drawing and producing parasitic, false, circles when the points are to cross the theta=180� line.

You can turn off this feature by passing "resolution=1" to the polar() method. This is the default in SVN versions of matplotlib, and will be in the next releases.

You've clearly done a lot of work on the Smith chart plotting already... It would be great to package that code into something for general use and include in the matplotlib core.

Mike

···

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Michael Droettboom
Science Software Branch
Operations and Engineering Division
Space Telescope Science Institute
Operated by AURA for NASA

Hello Mike,

Thanks for your advice. I think this is exactly what I need. I am not sure
how to use this option, might you help me?

I use simply the following lines in my code:

self.figure.clf()
self.axes = self.figure.add_axes([0.1,0.1,0.8,0.8], projection='polar',
aspect='equal')

and later:
self.axes.plot(angle(data),abs(data),label=title,linewidth = 2,zorder=10)

Where should I change the resolution feature? With each plot or with figure
object?

The code is currently open source and available via emGine software
(http://www.petr-lorenz.com/emgine/index.php?option=com_content&view=article
&id=46&Itemid=56)

I am also willing to split smithchart plot as part of matplotlib, this would
be great I think.

Best regards,
Sherif

···

-----Original Message-----
From: Michael Droettboom [mailto:mdroe@…31…]
Sent: Thursday, March 19, 2009 1:01 PM
To: Sherif Ahmed
Cc: matplotlib-devel@lists.sourceforge.net
Subject: Re: [matplotlib-devel] Polar Plot

Sherif Ahmed wrote:

Hello all,

I am using matplotlib in order to generate a scientific drawing called
“Smith Chart”. It consists of many shifted circles drawn in polar
plot. This chart is widely used in electrical engineering field.

I am facing a problem now with the new version of matplotlib. After
trying around I figured out that the plot function does not connect
the given points in straight lines however by a circle or a circle
sector. This causes a very wrong drawing and producing parasitic,
false, circles when the points are to cross the theta=180° line.

You can turn off this feature by passing "resolution=1" to the polar()
method. This is the default in SVN versions of matplotlib, and will be
in the next releases.

You've clearly done a lot of work on the Smith chart plotting already...
It would be great to package that code into something for general use
and include in the matplotlib core.

Mike

------------------------------------------------------------------------

------------------------------------------------------------------------

------------------------------------------------------------------------

----------------------------------------------------------------------------
--

Apps built with the Adobe(R) Flex(R) framework and Flex Builder(TM) are
powering Web 2.0 with engaging, cross-platform capabilities. Quickly and
easily build your RIAs with Flex Builder, the Eclipse(TM)based development
software that enables intelligent coding and step-through debugging.
Download the free 60 day trial. http://p.sf.net/sfu/www-adobe-com
------------------------------------------------------------------------

_______________________________________________
Matplotlib-devel mailing list
Matplotlib-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/matplotlib-devel

--
Michael Droettboom
Science Software Branch
Operations and Engineering Division
Space Telescope Science Institute
Operated by AURA for NASA

Hello,

   Does anyone know how I could plot contours on a chart like this?

thanks,

Robert

···

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