contour plot in semi-circle domain

Community matplotlib-users
1

Hi!

I want to use polar plot and write contour in semi-circle domain.But I can't
do so.

Here is a part of my code.

···

-----------------------------
from pylab import *
from scipy import *

fig=figure(figsize=(10,10))
ax=fig.add_axes([0.1,0.1,0.8,0.8],polar=True)

axis([0, pi, 0, 1])

show()
----------------------------

I thought that "axis([0,pi,0,1])" make the writing domain semi-circle,
but complete circle was written as domain.

Does anyone know how I should write?

Many thanks,

Kenshi
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2

With "polar" projection, it is not possible to make semi-circle domain.
You need to make a custom projection
(http://matplotlib.sourceforge.net/devel/add_new_projection.html). But
it would not be easy for a normal user.

Another option is to use mpl_toolkits.axisartist (distributed with mpl
1.0). However, learning curve of the axisartist is also steep. You may
play around with the last figure in the example below.

http://matplotlib.sourceforge.net/examples/axes_grid/demo_floating_axes.html

Regards,

-JJ

···

On Tue, Sep 14, 2010 at 12:09 AM, Kenshi hibino <hibino@...3274...> wrote:

I thought that "axis([0,pi,0,1])" make the writing domain semi-circle,
but complete circle was written as domain.

Does anyone know how I should write?

3

Jae-Joon Lee wrote:

Another option is to use mpl_toolkits.axisartist (distributed with mpl
1.0). However, learning curve of the axisartist is also steep. You may
play around with the last figure in the example below.

http://matplotlib.sourceforge.net/examples/axes_grid/demo_floating_axes.html

Jae-Joon,
Thanks for the quick reply and good advice.

Second option you recommended is seemed to work well.
My code modified from example is attached.

But, in semi-circle domain I can't write contour label using clabel().
Do you know the reason why? http://old.nabble.com/file/p29737063/test2.py
test2.py

For reference my system is python(x,y) on Windows and mpl version is 1.0

Thanks again.

Kenshi

···

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4

Kenshi,

I'm sorry that I completely forgot about this issue.

I just took a look and it seems to be due to a bug in clabel routine.
The fix is easy and I'll commit it soon. Meanwhile, here is a work
around. Basically, you need to draw a contour in "ax3", not in
"aux_ax3".

First of all, you can populate Z without for loops (note that I
changed X, Y to Theta, R).

Theta, R = meshgrid(theta, r)

Z = (Theta/90.)**2 + (R-2)**2

Now, instead of aux_ax3.contour, use

CS = aux_contour(aux_ax3, Theta, R, Z,levels,colors='k')

where aux_contour is defined as

def aux_contour(aux_ax, aux_X, aux_Y, Z, *kl, **kwargs):
    ax = aux_ax._parent_axes
    shape_orig = Theta.shape
    TR = np.array([aux_X, aux_Y]).reshape((2, -1)).transpose() #
coordinates in aux_ax
    XY = aux_ax.transAux.transform(TR) # coordinates in ax
    X, Y = XY.transpose().reshape((2, shape_orig[0], shape_orig[1]))

    CS = ax.contour(X, Y, Z, *kl, **kwargs)

    return CS

And do clabel with the original axes (ax3). use_clabeltext will help
the labels aligned with contour lines.

ax3.clabel(CS,fontsize=10, use_clabeltext=True)

A complete example is attached.

Regards,

-JJ

tererer.py (3.23 KB)

···

On Fri, Sep 17, 2010 at 7:34 PM, Kenshi hibino <hibino@...3274...> wrote:

Jae-Joon Lee wrote:

Another option is to use mpl_toolkits.axisartist (distributed with mpl
1.0). However, learning curve of the axisartist is also steep. You may
play around with the last figure in the example below.

http://matplotlib.sourceforge.net/examples/axes_grid/demo_floating_axes.html

Jae-Joon,
Thanks for the quick reply and good advice.

Second option you recommended is seemed to work well.
My code modified from example is attached.

But, in semi-circle domain I can't write contour label using clabel().
Do you know the reason why? http://old.nabble.com/file/p29737063/test2.py
test2.py

For reference my system is python(x,y) on Windows and mpl version is 1.0

Thanks again.

Kenshi
--
View this message in context: http://old.nabble.com/contour-plot-in-semi-circle-domain-tp29699332p29737063.html
Sent from the matplotlib - users mailing list archive at Nabble.com.

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