matplotlib-users Mailing List for matplotlib

On Wed, Feb 16, 2011 at 9:16 AM, Stephan Markus <zw...@we...> wrote:
>
> Hi,
>
> I am trying to display some complex values in a polar plot. Displaying
> linear magnitude vs. angle - of course - works without any issues. But I'd
> rather display the logarithmic magnitute vs. angle. Since the data for the
> radius gets negative then, it'll be wrapped around / rotated by 180deg by
> matplotlib.
>
> How can I display negative values for the radius w/o having them rotated by
> 180deg?
>
> Of course I can add an offset to the data before plotting it but since my
> plot is interactive and I use the xdata/ydata of events I'd like them to
> represent the real data, without an offset. I thought it might be possible
> to achieve with a custom transformation but I don't actually get it to
> work.
>
> -Stephan
> --
> View this message in context:
> http://old.nabble.com/Polar-plot---problem-with-negative-values-for-radius-tp30936638p30936638.html
> Sent from the matplotlib - users mailing list archive at Nabble.com.
>
>
Stephan,
>From the polar axes object, you can call ax.set_rscale('log') and that will
automatically make the radial ticks scale and label the axes properly. You
can then input the original data as you would without worry of negative
values.
Let us know how that works for you!
Ben Root

Hi,
I've written two plot scripts for plotting functions f: R -> C.
(Scalar mappings of a real to a complex domain.)
The function plotcf(...) plots the modulus
as y value and the phase as color code.
The function stemcf(...) does the same, but
emulates a stem plot.
I attached also two demo scripts that show these
functions in action.
If you have any questions or improvements,
please tell me.
Feel free to add these scripts to the gallery
if you think they could be of a broader
interest.
-- Raoul

Hi,
I am trying to display some complex values in a polar plot. Displaying
linear magnitude vs. angle - of course - works without any issues. But I'd
rather display the logarithmic magnitute vs. angle. Since the data for the
radius gets negative then, it'll be wrapped around / rotated by 180deg by
matplotlib.
How can I display negative values for the radius w/o having them rotated by
180deg?
Of course I can add an offset to the data before plotting it but since my
plot is interactive and I use the xdata/ydata of events I'd like them to
represent the real data, without an offset. I thought it might be possible
to achieve with a custom transformation but I don't actually get it to work.
-Stephan
-- 
View this message in context: http://old.nabble.com/Polar-plot---problem-with-negative-values-for-radius-tp30936638p30936638.html
Sent from the matplotlib - users mailing list archive at Nabble.com.

> Ben, John: Later this week or next, I'll take a crack at adding both of these 
to quiver.py and 
> axes.py (one under the name "streamlines", the other as "streamplot"). 
This is a great idea. I've had some time to improve the code, and so you have 
something better to work with! If you have any questions or need the code 
modifying, I'm happy to help - should have free time at the weekend and next 
week. I've also added density in both directions (nice idea - hadn't thought 
about this) and variable color as well as width.
The new code is at http://www.atm.damtp.cam.ac.uk/people/tjf37/streamplot.py and 
there are new sample plots at 
http://www.atm.damtp.cam.ac.uk/people/tjf37/streamlines1.png and 
http://www.atm.damtp.cam.ac.uk/people/tjf37/streamlines2.png .
> You probably want to use a compound path (one object for the entire
> plot). See the tutorial 
athttp://matplotlib.sourceforge.net/users/path_tutorial.html, in
> particular the compound path for the histogram example near the end,
> and let me know if you have any questions.
John, thanks for the hints. In the end I used a LineCollection for each 
streamline because I didn't see how to set different properties (colour and 
width) for different portions of the line in the compound path. LineCollection 
performs well enough for this plot so I'm happy with this solution.
Tom

heya,
Is there an easy way to colour-code a Matplotlib histogram with a single set
of data?
So for example, you'd have a bell-shaped histogram, and the middle 50% might
be green, the regions 20% to the left and right of that might be yellow, and
the 5% either side beyond that could be red.
I couldn't seem to find anything in the Matplotlib options for this - any
suggestions?
Cheers,
Victor

On Tue, Feb 15, 2011 at 6:29 PM, Paul Leopardi
<pau...@ii...>wrote:
> Hi Benjamin,
> On 2011年2月16日 03:07:25 AM you wrote:
> > I have not figured out what is causing the difference between my
> computers.
> > This might be backend-dependent (and maybe version-dependent). Have you
> > tested your code on different backends?
>
> I don't know what you mean by different backends. What are the possible
> ones,
> and how do you configure them? Where is this documented?
> Best, Paul
>
http://matplotlib.sourceforge.net/faq/installing_faq.html#what-is-a-backend
Personally, I use the second approach with "matplotlib.use('GTKAgg')" or
whatnot. Based on what I saw you listed as available packages, you should
have TkAgg and WxAgg available.
Ben Root