matplotlib-users Mailing List for matplotlib (Page 4)

Thank you Lee. Thank you Chris and John, the problem is solved.
Chris, we did the method 1) as this was easier for us.
Sameer

On Sun, Aug 23, 2009 at 5:53 PM, John Hunter <jd...@gm...> wrote:

> On Sun, Aug 23, 2009 at 7:45 PM, Chris Barker<Chr...@no...>
> wrote:
>
> > This is a Bezier spline -- it can not exactly form a piece of a circle
> > (though it can get pretty close). You can probably find the math
> > somewhere for how to approximate a circle, but...
>
> somewhere like ... matplotlib.path.unit_circle (thanks to Michael D)
>
>    @classmethod
>    def unit_circle(cls):
>        """
>        (staticmethod) Returns a :class:`Path` of the unit circle.
>        The circle is approximated using cubic Bezier curves.  This
>        uses 8 splines around the circle using the approach presented
>        here:
>
>          Lancaster, Don.  `Approximating a Circle or an Ellipse Using Four
>          Bezier Cubic Splines <http://www.tinaja.com/glib/ellipse4.pdf>`_.
>        """
>        if cls._unit_circle is None:
>            MAGIC = 0.2652031
>            SQRTHALF = np.sqrt(0.5)
>            MAGIC45 = np.sqrt((MAGIC*MAGIC) / 2.0)
>
>            vertices = np.array(
>                [[0.0, -1.0],
>
>                 [MAGIC, -1.0],
>                 [SQRTHALF-MAGIC45, -SQRTHALF-MAGIC45],
>                 [SQRTHALF, -SQRTHALF],
>
>                 [SQRTHALF+MAGIC45, -SQRTHALF+MAGIC45],
>                 [1.0, -MAGIC],
>                 [1.0, 0.0],
>
>                 [1.0, MAGIC],
>                 [SQRTHALF+MAGIC45, SQRTHALF-MAGIC45],
>                 [SQRTHALF, SQRTHALF],
>
>                 [SQRTHALF-MAGIC45, SQRTHALF+MAGIC45],
>                 [MAGIC, 1.0],
>                 [0.0, 1.0],
>
>                 [-MAGIC, 1.0],
>                 [-SQRTHALF+MAGIC45, SQRTHALF+MAGIC45],
>                 [-SQRTHALF, SQRTHALF],
>
>                 [-SQRTHALF-MAGIC45, SQRTHALF-MAGIC45],
>                 [-1.0, MAGIC],
>                 [-1.0, 0.0],
>
>                 [-1.0, -MAGIC],
>                 [-SQRTHALF-MAGIC45, -SQRTHALF+MAGIC45],
>                 [-SQRTHALF, -SQRTHALF],
>
>                 [-SQRTHALF+MAGIC45, -SQRTHALF-MAGIC45],
>                 [-MAGIC, -1.0],
>                 [0.0, -1.0],
>
>                 [0.0, -1.0]],
>                np.float_)
>
>            codes = cls.CURVE4 * np.ones(26)
>            codes[0] = cls.MOVETO
>            codes[-1] = cls.CLOSEPOLY
>
>            cls._unit_circle = cls(vertices, codes)
>        return cls._unit_circle
>

Dear All,

I came across this peculiar bug when using patches together with savefig.

I first want to display the contour plot of the vector potentials in a
electrical machine, and the the contour plot of the flux density.

If I first define the patches (for the yoke and the magnets) and then
the first contour plot (for the vector potentials) and then, using the
same patch definitions, the second contour plot (for the flux density)

...
#Patch definitions
inner_yoke=Wedge(...)
outer_yoke=Wedge(...)
inner_N_magnet=Wedge(...)
outer_S_magnet=Wedge(...)
inner_S_magnet=Wedge(...)
outer_N_magnet=Wedge(...)

plt.figure(1)
CS=plt.contour(x,y,Az,40)
ax=plt.gca()
ax.add_patch(inner_yoke)
ax.add_patch(outer_yoke)
ax.add_patch(inner_N_magnet)
ax.add_patch(outer_S_magnet)
ax.add_patch(inner_S_magnet)
ax.add_patch(outer_N_magnet)
plt.savefig('Az-savefig.png')

plt.figure(2)
CS=plt.contour(x,y,Bmag,50)
CS=plt.contourf(x,y,Bmag,50)
ax=plt.gca()
ax.add_patch(inner_yoke)
ax.add_patch(outer_yoke)
ax.add_patch(inner_N_magnet)
ax.add_patch(outer_S_magnet)
ax.add_patch(inner_S_magnet)
ax.add_patch(outer_N_magnet)
plt.savefig('Bmag-savefig.png')

plt.show()

the two figures are displayed correctly on the screen, see
http://staff.ee.sun.ac.za/pjrandewijk/matplotlib/Az-snapshot.png and
http://staff.ee.sun.ac.za/pjrandewijk/matplotlib/Bmag-snapshot.png

However, if I look at the saved PNG files
http://staff.ee.sun.ac.za/pjrandewijk/matplotlib/Az-savefig.png and
http://staff.ee.sun.ac.za/pjrandewijk/matplotlib/Bmag-savefig.png the
patches on Bmag-savefig.png are all wrong.  It looks as if the Patches
are on a totally different scale??

A workaround is to copy the Patch definitions before plt.figure(1) and
paste it just before plt.figure(2) but which is not a very elegant
solution as one has to define the exact same patches twice, i.e.

...
#Patch definitions - Take I
inner_yoke=Wedge(...)
outer_yoke=Wedge(...)
inner_N_magnet=Wedge(...)
outer_S_magnet=Wedge(...)
inner_S_magnet=Wedge(...)
outer_N_magnet=Wedge(...)

plt.figure(1)
CS=plt.contour(x,y,Az,40)
ax=plt.gca()
ax.add_patch(inner_yoke)
ax.add_patch(outer_yoke)
ax.add_patch(inner_N_magnet)
ax.add_patch(outer_S_magnet)
ax.add_patch(inner_S_magnet)
ax.add_patch(outer_N_magnet)
plt.savefig('Az-savefig.png')

#Exactly the same Patch definitions - Take II
inner_yoke=Wedge(...)
outer_yoke=Wedge(...)
inner_N_magnet=Wedge(...)
outer_S_magnet=Wedge(...)
inner_S_magnet=Wedge(...)
outer_N_magnet=Wedge(...)

plt.figure(2)
CS=plt.contour(x,y,Bmag,50)
CS=plt.contourf(x,y,Bmag,50)
ax=plt.gca()
ax.add_patch(inner_yoke)
ax.add_patch(outer_yoke)
ax.add_patch(inner_N_magnet)
ax.add_patch(outer_S_magnet)
ax.add_patch(inner_S_magnet)
ax.add_patch(outer_N_magnet)
plt.savefig('Bmag-savefig.png')

plt.show()

Kind regards,

Peter-Jan

I think you can just copy the axes_grid.inset_locator.py file and use
it after deleting a few lines of code that gives some ImportError.

However, here is a some related post.

http://www.nabble.com/embedding-figures-inside-another-%28coordinates%29-td22826126.html#a22832238


Just replace the bbox coordinate of the inset axes, eg.,

ip = InsetPosition(ax, [1.1, 0., 0.1, 0.5])

Note that the coordinate is the normalized axes coordinate of the parent axes.

*axes_locator* takes a callable object which takes arguments of the
axes itself and the renderer, and subsequently returns the bbox
object. Once set, the axes_locator is called at the drawing time and
adjust the axes position to the returned bbox.

-JJ


On Sun, Aug 23, 2009 at 10:42 AM, Patrick Marsh<pat...@gm...> wrote:
> Hi JJ,
>
> I'm not sure I understand how to properly set the axe_locator.  Below
> is my snippet of code that I use to create my contourf plot and then
> create the colorbar.  I'm unsure how I would modify it to do as you
> suggested.  Any help would be appreciated.
>
>        plot = ax.contourf(xc, yc, data, cmap=cmap, levels=clevels)
>        cax = plt.axes([0.85, 0.125, 0.035, 0.325])
>        cbar = fig.colorbar(plot, format='%.1f', cax=cax)
>
> I should also point out that the reason I'm not using the axes_grid
> toolkit is because I'm constrained to develop based on the current
> Enthought release.
>
> Patrick
> ---
> Patrick Marsh
> Graduate Research Assistant
> School of Meteorology
> University of Oklahoma
> http://www.patricktmarsh.com
>
>
>
>
> On Sat, Aug 22, 2009 at 10:37 PM, Jae-Joon Lee<lee...@gm...> wrote:
>> What you need is to adjust the axes position of the colorbar at the
>> drawing time (because the axes position of the contour plot is
>> adjusted only during the drawing time).
>> You may do this by properly setting the axe_locator property of the axes.
>>
>> If you're using mpl 0.99, axes_grid toolkit may be helpful.
>> I just posted a simple example with the screenshot in the link below.
>>
>> http://abitofpythonabitofastronomy.blogspot.com/2009/08/creating-color-bar-using-inset-axes.html
>>
>> Regards,
>>
>> -JJ
>>
>>
>>
>> On Sat, Aug 22, 2009 at 9:51 PM, Patrick Marsh<pat...@gm...> wrote:
>>> Greeting MPL world,
>>>
>>> I have a contourf plot where the aspect ratio is 1.  I need to add a
>>> colorbar to the plot in a manner that keeps the colorbar in the same
>>> place relative to the contourf plot (good.png), even if the parent
>>> window is resized.  I can do this with text, but haven't been able to
>>> figure out how to do it with a colorbar.  To the best of my knowledge,
>>> there are two ways forward.
>>>
>>> 1.)  I can create an entirely new axis instance (cax) but will need to
>>> find a way to define the axes in a relative way to the original ax
>>> instance.  As it stands now, I can only define axes in terms of the
>>> total figure size.  As a result, the figure looks like it does in
>>> bad.png
>>>
>>>
>>> 2.)  I can use the original ax instance, but need to find a way to
>>> have more control over the colorbar placement.  For example, it needs
>>> to "sit" on the x-axis and not be centered in the middle of the yaxis.
>>>  Using shrink and aspect, I can get the plot size to be correct,
>>> however it's position is centered on the yaxis as in bad2.png
>>>
>>> Is there a way to accomplish what I'm needing to do and I'm just missing it?
>>>
>>> Thanks in advance,
>>> Patrick
>>> ---
>>> Patrick MarshC
>>> Graduate Research Assistant
>>> School of Meteorology
>>> University of OklahomaC
>>> http://www.patricktmarsh.com
>>>
>>> ------------------------------------------------------------------------------
>>> Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day
>>> trial. Simplify your report design, integration and deployment - and focus on
>>> what you do best, core application coding. Discover what's new with
>>> Crystal Reports now.  http://p.sf.net/sfu/bobj-july
>>> _______________________________________________
>>> Matplotlib-users mailing list
>>> Mat...@li...
>>> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>>>
>>>
>>
>

Hi!

After installing matplotlib 0.99.0 (over 0.98.6) I started to get the 
following exceptions while checking hitlist:

Traceback (most recent call last):
  File "C:\Python26\Lib\site-packages\matplotlib\artist.py", line 231, 
in hitlist
    hascursor,info = self.contains(event)
  File "C:\Python26\Lib\site-packages\matplotlib\lines.py", line 286, in 
contains
    path, affine = self._transformed_path.get_transformed_path_and_affine()
AttributeError: 'NoneType' object has no attribute 
'get_transformed_path_and_affine'
while checking <class 'matplotlib.lines.Line2D'>
...(several times the same exception for one mouse event)

The exception is produced with 'motion_notify_event' when trying to get 
the hitlist.

How could I solve this problem?

Thanks
Romi

Hi,

I am new to matplotlib. 
I am using boxplot and i wanted to mark current value or any special value
on the box plot. How do i achieve this? Something like below.

Thanks in advance,

--- [---X------]-----
--------------[---------]-------X--- 
-- 
View this message in context: http://www.nabble.com/showing-current-value-on-boxplot-tp25115648p25115648.html
Sent from the matplotlib - users mailing list archive at Nabble.com.

Hi Scripper,

I'm not sure what you would like to know, but it is possible to change
the tick settings on the 3D axes in the same way as for normal 2D
axes. For example:

from mpl_toolkits.mplot3d import Axes3D
from matplotlib import cm
from matplotlib.ticker import LinearLocator, FixedLocator, FormatStrFormatter
import matplotlib.pyplot as plt
import numpy as np

fig = plt.figure()
ax = Axes3D(fig)
X = np.arange(-5, 5, 0.25)
Y = np.arange(-5, 5, 0.25)
X, Y = np.meshgrid(X, Y)
R = np.sqrt(X**2 + Y**2)
Z = np.sin(R)
ax.plot_surface(X, Y, Z, rstride=1, cstride=1, cmap=cm.jet)
ax.set_zlim3d(-1.01, 1.01)

ax.w_zaxis.set_major_locator(LinearLocator(10))
ax.w_zaxis.set_major_formatter(FormatStrFormatter('%.03f'))

plt.show()

Hope this helps,

Reinier

On Tue, Aug 18, 2009 at 7:16 PM, scripper<Scr...@gm...> wrote:
>
> Hi everybody,
> i am a newbie on Matplotlib and wanna know whether there is already tick
> setting on x,y,z axes in 3D plot. By now i just know on 2-dimension which
> listed on the gallery.
> Thanks very much!
> --
> View this message in context: http://www.nabble.com/plot3d-ticker-setting-tp25029488p25029488.html
> Sent from the matplotlib - users mailing list archive at Nabble.com.
>
>
> ------------------------------------------------------------------------------
> Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day
> trial. Simplify your report design, integration and deployment - and focus on
> what you do best, core application coding. Discover what's new with
> Crystal Reports now.  http://p.sf.net/sfu/bobj-july
> _______________________________________________
> Matplotlib-users mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>



-- 
Reinier Heeres
Tel: +31 6 10852639

Hi German,

Although I haven't tried it, it should certainly work.

Please look at the examples which embed QT4:
http://matplotlib.sourceforge.net/examples/animation/animation_blit_qt4.html
and http://matplotlib.sourceforge.net/examples/user_interfaces/embedding_in_qt4.html.

All you'll need to do is replace the add_subplot() call with something
like ax = Axes3D(fig). Then you can combine the QT4 example with the
mplot3d examples, e.g.
http://matplotlib.sourceforge.net/examples/mplot3d/surface3d_demo.html

Cheers,
Reinier


On Sun, Aug 23, 2009 at 11:16 AM, German Ocampo<ger...@gm...> wrote:
> Good morning
> I'm working in a project in QT4 and I need to create a 3D graph embedded in
> a Widget form. Is it possible to do it? and where I could get an example?
>
> Thanks
> German
> ------------------------------------------------------------------------------
> Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day
> trial. Simplify your report design, integration and deployment - and focus
> on
> what you do best, core application coding. Discover what's new with
> Crystal Reports now.  http://p.sf.net/sfu/bobj-july
> _______________________________________________
> Matplotlib-users mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>
>



-- 
Reinier Heeres
Tel: +31 6 10852639

When you have a problem like this with one install looking one place
and another install looking in another place making a symbolic link is
usually easier and more likely to catch everything than making a copy.
In your case you could have said:

ln -s /Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/site-packages
/Library/Python/2.5/site-packages

I'm glad you quickly found the root cause.

Phil


On Sat, Aug 22, 2009 at 6:36 PM, per freem<per...@gm...> wrote:
> i figured out what i did wrong and so am writing it here in case it
> helps others.
>
> the basic issue is that the .ttf font was missing in the new
> matplotlib directory. to discover this, i ran python with
> --verbose-debug as suggested in previous threads by others.  then i
> copied my version of Helvetica.ttf into:
>
> /Library/Python/2.5/site-packages/matplotlib/mpl-data/fonts/pdfcorefonts
>
> and
>
> /Library/Python/2.5/site-packages/matplotlib/mpl-data/fonts/ttf
>
> then everything worked and i was able to change fonts to helvetica.
>
> thanks.
>
> On Sat, Aug 22, 2009 at 7:12 PM, per freem<per...@gm...> wrote:
>> Hi all,
>>
>> the following code used to work for me in matplotlib-0.98 to make a
>> simple scatter plot and change the font from the default font to
>> Helvetica (I am using mac os x).
>>
>> import matplotlib
>> matplotlib.use('PDF')
>> import matplotlib.pyplot as plt
>> from matplotlib import rc
>> rc('font',**{'family':'sans-serif','sans-serif':['Helvetica']})
>> from scipy import *
>> from numpy import *
>>
>> my_fig = plt.figure(figsize=(6,5), dpi=100)
>> x = rand(100)*300
>> y = rand(100)
>> plt.scatter(x, y)
>> plt.rcParams['xtick.direction'] = 'out'
>> plt.rcParams['ytick.direction'] = 'out'
>> c = 0.05*300.5
>> plt.xlim([0-c, 300+c])
>> plt.ylim([-0.05, 1.05])
>> plt.savefig('x.pdf')
>>
>> i recently upgraded to matplotlib-0.99 and the changing of the font
>> using the above method no longer works. the figure is plotted the
>> same, but the font remains the default matplotlib font.
>>
>> one potential problem in the installation was this: i installed
>> matplotlib-0.99 using the dmg prepackaged binary installer. this
>> installed matplotlib in the directory:
>>
>> /Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/site-packages
>>
>> however, for some reason ipython / python2.5 was looking for packages in:
>>
>> /Library/Python/2.5/site-packages
>>
>> and so matplotlib/mpl_toolkits was not found. so I copied the
>> directories 'matplotlib' and 'mpl_toolkits' from
>> /Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/site-packages
>> to /Library/Python/2.5/site-packages.  Perhaps this was the cause of
>> the problem?
>>
>> thanks for your help.
>>
>> (i run my code via ipython, by the way.)
>>
>
> ------------------------------------------------------------------------------
> Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day
> trial. Simplify your report design, integration and deployment - and focus on
> what you do best, core application coding. Discover what's new with
> Crystal Reports now.  http://p.sf.net/sfu/bobj-july
> _______________________________________________
> Matplotlib-users mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>

On Sun, Aug 23, 2009 at 7:45 PM, Chris Barker<Chr...@no...> wrote:

> This is a Bezier spline -- it can not exactly form a piece of a circle
> (though it can get pretty close). You can probably find the math
> somewhere for how to approximate a circle, but...

somewhere like ... matplotlib.path.unit_circle (thanks to Michael D)

    @classmethod
    def unit_circle(cls):
        """
        (staticmethod) Returns a :class:`Path` of the unit circle.
        The circle is approximated using cubic Bezier curves.  This
        uses 8 splines around the circle using the approach presented
        here:

          Lancaster, Don.  `Approximating a Circle or an Ellipse Using Four
          Bezier Cubic Splines <http://www.tinaja.com/glib/ellipse4.pdf>`_.
        """
        if cls._unit_circle is None:
            MAGIC = 0.2652031
            SQRTHALF = np.sqrt(0.5)
            MAGIC45 = np.sqrt((MAGIC*MAGIC) / 2.0)

            vertices = np.array(
                [[0.0, -1.0],

                 [MAGIC, -1.0],
                 [SQRTHALF-MAGIC45, -SQRTHALF-MAGIC45],
                 [SQRTHALF, -SQRTHALF],

                 [SQRTHALF+MAGIC45, -SQRTHALF+MAGIC45],
                 [1.0, -MAGIC],
                 [1.0, 0.0],

                 [1.0, MAGIC],
                 [SQRTHALF+MAGIC45, SQRTHALF-MAGIC45],
                 [SQRTHALF, SQRTHALF],

                 [SQRTHALF-MAGIC45, SQRTHALF+MAGIC45],
                 [MAGIC, 1.0],
                 [0.0, 1.0],

                 [-MAGIC, 1.0],
                 [-SQRTHALF+MAGIC45, SQRTHALF+MAGIC45],
                 [-SQRTHALF, SQRTHALF],

                 [-SQRTHALF-MAGIC45, SQRTHALF-MAGIC45],
                 [-1.0, MAGIC],
                 [-1.0, 0.0],

                 [-1.0, -MAGIC],
                 [-SQRTHALF-MAGIC45, -SQRTHALF+MAGIC45],
                 [-SQRTHALF, -SQRTHALF],

                 [-SQRTHALF+MAGIC45, -SQRTHALF-MAGIC45],
                 [-MAGIC, -1.0],
                 [0.0, -1.0],

                 [0.0, -1.0]],
                np.float_)

            codes = cls.CURVE4 * np.ones(26)
            codes[0] = cls.MOVETO
            codes[-1] = cls.CLOSEPOLY

            cls._unit_circle = cls(vertices, codes)
        return cls._unit_circle

Sameer Regmi wrote:
> We are working on plotting mesh (in 
> hermes2d: http://hpfem.math.unr.edu/projects/hermes2d-new/)

> In the hermes2d examples curves are defined as [4, 7, 45] where 4,7 
> are vertices indices, and 45 is center angle.

> 1) matplot.path porvides a way to plot curve with three points
> http://matplotlib.sourceforge.net/api/path_api.html#module-matplotlib.path

This is a Bezier spline -- it can not exactly form a piece of a circle 
(though it can get pretty close). You can probably find the math 
somewhere for how to approximate a circle, but...

> 2) matplot.patch.arc provides a way to plot an arc
>  http://matplotlib.sourceforge.net/api/artist_api.html#module-matplotlib.patches
> 
>  but it needs
>  -> center of circle
>  -> start angle
>  -> end angle
>  -> radius of circle
>    we have to calculate all these with data available to us

Since this actually plots s circle, I think it's a better bet. It should
be pretty straightforward coordinate geometry to find those parameters 
from the ones you have -- and you  only have to write that once!

This page (or others like it) might help you get started:

http://www.codecogs.com/reference/maths/analytical_geometry/the_coordinate_geometry_of_a_circle.php

HTH,

-Chris

-- 
Christopher Barker, Ph.D.
Oceanographer

Emergency Response Division
NOAA/NOS/OR&R            (206) 526-6959   voice
7600 Sand Point Way NE   (206) 526-6329   fax
Seattle, WA  98115       (206) 526-6317   main reception

Chr...@no...

I just realized that by clicking once on the pan button, the cursor goes into pan, and clicking again, it goes back to the arrow. Same for some of the other buttons.  I realized this by looking at the code.  I would recommend that the documentation at the link shown below say something about this.

http://matplotlib.sourceforge.net/users/navigation_toolbar.html

Marc Desmarais

Long Beach, CA, 90814



      

To create a cursor that only pans horizontally, I'm thinking of writing a special version of drag_pan in  backend_bases.py   It would call  drag_pan in axes.py with the key argument set to 'x'

Any advice, suggestions?


backend_bases.py :

def my_drag_pan(self, event):
    'the drag callback in pan/zoom mode'

    for a, ind in self._xypress:
        a.drag_pan(self._button_pressed, 'x', event.x, event.y)
    self.dynamic_update()
    
#
# In axes, up/down motion is prevented when the 'x' key is down
#
axes.py

def drag_pan(self, button, key, x, y):
   ...
   elif key=='x':
                dy = 0
    ...

Marc Desmarais

Long Beach, CA, 90814

--- On Wed, 8/12/09, Eric Firing <ef...@ha...> wrote:

From: Eric Firing <ef...@ha...>
Subject: Re: [Matplotlib-users] pylab
To: "marc desmarais" <mde...@ya...>
Cc: "matplotlib-users" <mat...@li...>
Date: Wednesday, August 12, 2009, 9:59 AM

marc desmarais wrote:
> I found a typo at "http://matplotlib.sourceforge.net/users/navigation_toolbar.html"
> 
> "If you press ‘x’ or ‘y’ while panning the motion will be contrained to the x or y axis, respectively."
> 

Thank you.  Now it is fixed.

> BTW, do you know how to constrain the panning function to left/right programmatically? I'm try to make a logic analyzer.

I don't know offhand, but I don't think that capability is in place.  I find holding down a key while panning to be a bit awkward, so I am also interested in alternatives.

> 
> Finally, is this the best place to post my questions? (I suspect not...)

Yes, matplotlib-users is the right place.  I assume you intended to "reply-to-all" on that last one, so intended it to go to the list. Apparently the settings on this list are unusual in that one must explicitly "reply-to-all"; it is not automatic that one's reply goes to the list.

Eric

> 
> --- On *Mon, 8/10/09, Eric Firing /<ef...@ha...>/* wrote:
> 
> 
>     From: Eric Firing <ef...@ha...>
>     Subject: Re: [Matplotlib-users] pylab
>     To: "marc desmarais" <mde...@ya...>
>     Cc: mat...@li...
>     Date: Monday, August 10, 2009, 7:22 PM
> 
>     marc desmarais wrote:
>      > Are there still two pylabs?  Are the following two web pages
>     referring to the same pylab?
> 
>     Not exactly:
>      >
>     This one is a vision or proposal, open for discussion:
>      > http://www.scipy.org/PyLab
> 
>     This one is real:
>      > http://matplotlib.sourceforge.net/
>      >
> 
>     The pylab interface to the matplotlib plotting library has some of
>     the characteristics the author of the first link is talking about,
>     but the trend has been away from some aspects of that vision, not
>     towards it.
> 
>     For more about the real pylab, see
>     http://matplotlib.sourceforge.net/faq/usage_faq.html#matplotlib-pylab-and-pyplot-how-are-they-related
> 
> 
>      > I'm a bit confused (trying to get the Scipy, Numpy, Pylab,
>     Matplolib story straight, before I plunge in)
> 
>     Numpy is the common core, providing N-dimensional arrays and math;
>     matplotlib is a plotting library, using numpy; scipy is a collection
>     of math/science functionality, also using numpy.
> 
>     But don't forget ipython, which provides a nice interactive shell:
>     http://ipython.scipy.org/moin/
> 
>     Eric
> 
>      >
>      > Marc Desmarais
>      > Long Beach, CA, 90814
> 
> 




      

On Sun, Aug 23, 2009 at 1:24 PM, Eric Firing<ef...@ha...> wrote:
> Dr. Phillip M. Feldman wrote:
>> I've been trying to understand how colormaps work.  I've been through the
>> Matplotlib User's Guide (Release 0.98.6svn, dated June 14, 2009), but the
>> section on colormaps has not yet been written.  If anyone can point me to
>
> This is my fault; I need to write that.
>
>> documentation or provide an explanation, I'd be grateful.
>
> This may help:
> http://matplotlib.sourceforge.net/api/colors_api.html
> http://matplotlib.sourceforge.net/api/cm_api.html
>
> and this:
>
> http://matplotlib.sourceforge.net/examples/pylab_examples/custom_cmap.html
>
> Beware: the posted docs are current, so may include functions that are
> not in the version of mpl you have installed.
>
> If you search for "cmap" using the search box in the doc webpage
> sidebar, you will get many more examples of the use of colormaps.
> Browsing these examples may be the quickest way of getting the basic
> ideas of how cmaps (and their partners, norms) are used.
>
> Looking at the source code is also helpful.

This example may be instructive: it takes a list of colors and creates
a colormap that interpolates smoothly between them from normalized
0..1.

But yes, a tutorial on the sphinx site would be great (at the sprint
yesterday one of the students wrote a nice image tut but I haven't
gotten it from him yet for upload)


    @staticmethod
    def from_list(name, colors, N=256):
        """
        Make a linear segmented colormap with *name* from a sequence
        of *colors* which evenly transitions from colors[0] at val=1
        to colors[-1] at val=1.  N is the number of rgb quantization
        levels.
        """

        ncolors = len(colors)
        vals = np.linspace(0., 1., ncolors)

        cdict = dict(red=[], green=[], blue=[])
        for val, color in zip(vals, colors):
            r,g,b = colorConverter.to_rgb(color)
            cdict['red'].append((val, r, r))
            cdict['green'].append((val, g, g))
            cdict['blue'].append((val, b, b))

        return LinearSegmentedColormap(name, cdict, N)

Dr. Phillip M. Feldman wrote:
> I've been trying to understand how colormaps work.  I've been through the
> Matplotlib User's Guide (Release 0.98.6svn, dated June 14, 2009), but the
> section on colormaps has not yet been written.  If anyone can point me to

This is my fault; I need to write that.

> documentation or provide an explanation, I'd be grateful.

This may help:
http://matplotlib.sourceforge.net/api/colors_api.html
http://matplotlib.sourceforge.net/api/cm_api.html

and this:

http://matplotlib.sourceforge.net/examples/pylab_examples/custom_cmap.html

Beware: the posted docs are current, so may include functions that are 
not in the version of mpl you have installed.

If you search for "cmap" using the search box in the doc webpage 
sidebar, you will get many more examples of the use of colormaps. 
Browsing these examples may be the quickest way of getting the basic 
ideas of how cmaps (and their partners, norms) are used.

Looking at the source code is also helpful.

Eric

Werner F. Bruhin wrote:
> I previously used version '0.90.1' and could do something along these lines.
>
> figure.add_axes
> ...  etc
> canvas.Refresh()
>
> User makes a new selection and in the code I do:
>
> figure.clear()
> figure.add_axes
> ... etc
> canvas.Refresh()
>
> With 0.99 and wxAgg on Windows Vista with wxPython 2.8.10.1 Unicode and 
> Python 2.5.4 this does not work.
>
> The "old" figure remains and the new one is only shown when I resize the 
> frame which contains a wx.Splitter with the right window containing the 
> mpl.figure on a panel.
>
> If I add canvas.draw() then most is shown, except some mpl.text elements 
> (e.g. figure.title) - which again are shown if I resize.
>
> Appreciate any hint on how to solve this.
>   
I had to add the canvas.Draw() call, but I had that to early in my code, 
i.e. the title was only added to the figure after I had called Draw() - 
0.90 was forgiven me this stupid mistake.

Sorry for the noise.
Werner

I previously used version '0.90.1' and could do something along these lines.

figure.add_axes
...  etc
canvas.Refresh()

User makes a new selection and in the code I do:

figure.clear()
figure.add_axes
... etc
canvas.Refresh()

With 0.99 and wxAgg on Windows Vista with wxPython 2.8.10.1 Unicode and 
Python 2.5.4 this does not work.

The "old" figure remains and the new one is only shown when I resize the 
frame which contains a wx.Splitter with the right window containing the 
mpl.figure on a panel.

If I add canvas.draw() then most is shown, except some mpl.text elements 
(e.g. figure.title) - which again are shown if I resize.

Appreciate any hint on how to solve this.

Werner

Hello everyone,

I was playing around with matplotlib, created a plot that allows users to add nodes (axis is set off as it's going to be used for graph data structuer purposes, hence don't want the y-x axis, is there another way to hide them as well?).

Basically the program below allows person press the 'n' button, and then can click on any point on the plot and a small circular marker will appear.

I have two questions:

1) You will notice that during the first 2 marker inputs, the plot rescales it self. I don't really know why that's happening, any idea?
2) Is it possible to disallow users of creating to marker points ontop of each other, so that no markers will overlap (even if the edges)?

Thank you.




#### Code
from pylab import *
from matplotlib.widgets import *

fig = plt.figure()
ax = fig.add_subplot(111)
fig.set_facecolor('w')
ax.set_axis_off()
ax.set_title('Test 1')
cid = None
def onClick(event):
"""docstring for onClick"""
ax.plot([event.xdata], [event.ydata], 'bo', picker=5, markersize=15)
draw()
fig.canvas.mpl_disconnect(cid)
def onPick(event):
"""docstring for onPick"""
artist = event.artist
artist.set_color('r')
draw()
def add_node(event):
"""docstring for press"""
if event.key=="n":
global cid
fig.canvas.mpl_disconnect(cid)
cid = fig.canvas.mpl_connect('button_press_event',onClick)
fig.canvas.mpl_connect('key_press_event', add_node)
fig.canvas.mpl_connect('pick_event',onPick)

plt.show()


      

I've been trying to understand how colormaps work.  I've been through the
Matplotlib User's Guide (Release 0.98.6svn, dated June 14, 2009), but the
section on colormaps has not yet been written.  If anyone can point me to
documentation or provide an explanation, I'd be grateful.
-- 
View this message in context: http://www.nabble.com/how-do-colormaps-work--tp25104198p25104198.html
Sent from the matplotlib - users mailing list archive at Nabble.com.

Dr. Phillip M. Feldman wrote:
> Having to hit Enter is not a major problem, but I'm still not getting
> anything displayed.

i guess that might be because the "show" command before the loop blocks
the program.

you can omit the line with "show" or start ipython with
ipython -pylab
both versions work here.


good luck,
sebastian.

Having to hit Enter is not a major problem, but I'm still not getting
anything displayed.

I noticed that you used pyplot.draw() instead of pyplot.show().  I've
checked the available documentation, but haven't been able to understand the
difference between these.

I should have mentioned that I'm running this script from the IPython
prompt.

Thanks!
-- 
View this message in context: http://www.nabble.com/how-to-generate-one-plot-per-key-press--tp25100658p25104051.html
Sent from the matplotlib - users mailing list archive at Nabble.com.

Hi JJ,

I'm not sure I understand how to properly set the axe_locator.  Below
is my snippet of code that I use to create my contourf plot and then
create the colorbar.  I'm unsure how I would modify it to do as you
suggested.  Any help would be appreciated.

        plot = ax.contourf(xc, yc, data, cmap=cmap, levels=clevels)
        cax = plt.axes([0.85, 0.125, 0.035, 0.325])
        cbar = fig.colorbar(plot, format='%.1f', cax=cax)

I should also point out that the reason I'm not using the axes_grid
toolkit is because I'm constrained to develop based on the current
Enthought release.

Patrick
---
Patrick Marsh
Graduate Research Assistant
School of Meteorology
University of Oklahoma
http://www.patricktmarsh.com




On Sat, Aug 22, 2009 at 10:37 PM, Jae-Joon Lee<lee...@gm...> wrote:
> What you need is to adjust the axes position of the colorbar at the
> drawing time (because the axes position of the contour plot is
> adjusted only during the drawing time).
> You may do this by properly setting the axe_locator property of the axes.
>
> If you're using mpl 0.99, axes_grid toolkit may be helpful.
> I just posted a simple example with the screenshot in the link below.
>
> http://abitofpythonabitofastronomy.blogspot.com/2009/08/creating-color-bar-using-inset-axes.html
>
> Regards,
>
> -JJ
>
>
>
> On Sat, Aug 22, 2009 at 9:51 PM, Patrick Marsh<pat...@gm...> wrote:
>> Greeting MPL world,
>>
>> I have a contourf plot where the aspect ratio is 1.  I need to add a
>> colorbar to the plot in a manner that keeps the colorbar in the same
>> place relative to the contourf plot (good.png), even if the parent
>> window is resized.  I can do this with text, but haven't been able to
>> figure out how to do it with a colorbar.  To the best of my knowledge,
>> there are two ways forward.
>>
>> 1.)  I can create an entirely new axis instance (cax) but will need to
>> find a way to define the axes in a relative way to the original ax
>> instance.  As it stands now, I can only define axes in terms of the
>> total figure size.  As a result, the figure looks like it does in
>> bad.png
>>
>>
>> 2.)  I can use the original ax instance, but need to find a way to
>> have more control over the colorbar placement.  For example, it needs
>> to "sit" on the x-axis and not be centered in the middle of the yaxis.
>>  Using shrink and aspect, I can get the plot size to be correct,
>> however it's position is centered on the yaxis as in bad2.png
>>
>> Is there a way to accomplish what I'm needing to do and I'm just missing it?
>>
>> Thanks in advance,
>> Patrick
>> ---
>> Patrick MarshC
>> Graduate Research Assistant
>> School of Meteorology
>> University of OklahomaC
>> http://www.patricktmarsh.com
>>
>> ------------------------------------------------------------------------------
>> Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day
>> trial. Simplify your report design, integration and deployment - and focus on
>> what you do best, core application coding. Discover what's new with
>> Crystal Reports now.  http://p.sf.net/sfu/bobj-july
>> _______________________________________________
>> Matplotlib-users mailing list
>> Mat...@li...
>> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>>
>>
>

Good morning
I'm working in a project in QT4 and I need to create a 3D graph embedded in
a Widget form. Is it possible to do it? and where I could get an example?


Thanks

German

appologies - sys.stdin.read(1) blocks until you give it a new line
(<Enter>) that' s probably what you were having problems with.
           
Paul Ivanov, on 2009-08-23 01:14,  wrote:
> Try something like this:
> 
> 
> from os import sys
> from matplotlib import *
> from numpy.random import rand
> 
> fig= pyplot.figure(figsize=(8,8), dpi=120)
> pyplot.show()
> while True:
>     z= rand(20,20)
>     pyplot.imshow(z)
>     pyplot.draw()
> 
>     chr= sys.stdin.read(1)
>     if chr=='q': 
>         break
> 
> pyplot.close('all')
> 
> 
> cheers,
>     Paul
> 
> Dr. Phillip M. Feldman, on 2009-08-22 23:19,  wrote:
> > 
> > The following trivial program is supposed to generate one plot per key press
> > until the user presses 'q'.  Instead, nothing is displayed until the user
> > presses 'q'.  Any suggestions will be appreciated.
> > 
> > from os import sys
> > from matplotlib import *
> > from numpy.random import rand
> > 
> > while True:
> > 
> >    z= rand(20,20)
> >    fig= pyplot.figure(figsize=(8,8), dpi=120)
> >    pyplot.imshow(z)
> >    pyplot.show()
> > 
> >    chr= sys.stdin.read(1)
> >    if chr=='q': sys.exit(0)
> > -- 
> > View this message in context: http://www.nabble.com/how-to-generate-one-plot-per-key-press--tp25100658p25100658.html
> > Sent from the matplotlib - users mailing list archive at Nabble.com.
> > 
> > 
> > ------------------------------------------------------------------------------
> > Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day 
> > trial. Simplify your report design, integration and deployment - and focus on 
> > what you do best, core application coding. Discover what's new with 
> > Crystal Reports now.  http://p.sf.net/sfu/bobj-july
> > _______________________________________________
> > Matplotlib-users mailing list
> > Mat...@li...
> > https://lists.sourceforge.net/lists/listinfo/matplotlib-users

Try something like this:


from os import sys
from matplotlib import *
from numpy.random import rand

fig= pyplot.figure(figsize=(8,8), dpi=120)
pyplot.show()
while True:
    z= rand(20,20)
    pyplot.imshow(z)
    pyplot.draw()

    chr= sys.stdin.read(1)
    if chr=='q': 
        break

pyplot.close('all')


cheers,
    Paul

Dr. Phillip M. Feldman, on 2009-08-22 23:19,  wrote:
> 
> The following trivial program is supposed to generate one plot per key press
> until the user presses 'q'.  Instead, nothing is displayed until the user
> presses 'q'.  Any suggestions will be appreciated.
> 
> from os import sys
> from matplotlib import *
> from numpy.random import rand
> 
> while True:
> 
>    z= rand(20,20)
>    fig= pyplot.figure(figsize=(8,8), dpi=120)
>    pyplot.imshow(z)
>    pyplot.show()
> 
>    chr= sys.stdin.read(1)
>    if chr=='q': sys.exit(0)
> -- 
> View this message in context: http://www.nabble.com/how-to-generate-one-plot-per-key-press--tp25100658p25100658.html
> Sent from the matplotlib - users mailing list archive at Nabble.com.
> 
> 
> ------------------------------------------------------------------------------
> Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day 
> trial. Simplify your report design, integration and deployment - and focus on 
> what you do best, core application coding. Discover what's new with 
> Crystal Reports now.  http://p.sf.net/sfu/bobj-july
> _______________________________________________
> Matplotlib-users mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users

The following trivial program is supposed to generate one plot per key press
until the user presses 'q'.  Instead, nothing is displayed until the user
presses 'q'.  Any suggestions will be appreciated.

from os import sys
from matplotlib import *
from numpy.random import rand

while True:

   z= rand(20,20)
   fig= pyplot.figure(figsize=(8,8), dpi=120)
   pyplot.imshow(z)
   pyplot.show()

   chr= sys.stdin.read(1)
   if chr=='q': sys.exit(0)
-- 
View this message in context: http://www.nabble.com/how-to-generate-one-plot-per-key-press--tp25100658p25100658.html
Sent from the matplotlib - users mailing list archive at Nabble.com.