matplotlib-users Mailing List for matplotlib

On вторник, 02 јули 2013 at 11:04 AM, Ian Thomas wrote:
>
>You need to use a matplotlib.tri.Triangulation (your use of triplot does
>this for you behind the scenes anyway), something like:
>
>import matplotlib.tri as mtri
>triang = mtri.Triangulation(xpoints, ypoints)
>
>Now triang.triangles is an array of integers of shape (?, 3) such that
>triang.triangles[i,:] are the three indices of the points that comprise
>triangle i.  You will need to use these to determine the information you
>want.  The triplot example (
>http://matplotlib.org/examples/pylab_examples/triplot_demo.html) 
>does something similar, identifying which triangles are within a 
>particular circle; I guess in your case a simple approach would be to test if 
>the distance from the centre of each triangle edge to your circle of 
>interest is below some threshold or not.

Ian, thanks for you reply

Using threshold like you described is not applicable as there is no 
guarantee of minimum distance between pattern objects.

I wanted to replicate CGAL crust demo in Python, and in the meantime
I found the algorithm by Nina Amenta:

========================================
compute Vor(P);
let V be the Voronoi vertices of Vor(P);
compute Del(P U V);
E := 0;
for each edge pq in Del(P U V) do
  if p in P and q in P
      E := E U pq;
  endif
output E.
========================================

So, Voronoi vertices have property to cluster wanted objects in a manner
that we can use edges of Delaunay triangulation from original points and
Voronoi vertices of that same points, and simply check if they lay on
original points.

I used Deleanay and Voronoi functions from scipy.spatial and worth
mentioning is that I had hard time finding that edges from triangulation
can be found by this command:

========================================
t = Delaunay(PUV)
edges = t.points[t.vertices]
========================================

Cheers


>
>Incidentally, if you have a Triangulation object then subsequent 
>calls to functions like triplot can be of the form triplot(triang), which 
>will be faster than repeated calls to triplot(xpoints, ypoints) as in the 
>latter case a separate Delaunay triangulation needs to be performed for 
>each triplot call.
>
>Ian

Greetings!

Relative newbie here.

I'm trying to plot wind vectors using basemap quiver and to fit my ortho
projection. This is essentially a hack of Jeff Whitaker's animate.py found
at 

https://github.com/matplotlib/basemap/blob/master/examples/animate.py

The data source I'm connecting to, however, has the latitudes in decreasing
order, so I get the "lats and lons must be in increasing order!" exception
when trying to use the transform_vector method which seems to be required to
fit the vectors to the projection.  (ugliness occurs when failing to
transform)

What would be the best way to transform latitudes (to increasing) as needed
by transform_vector, while also accounting for the data order of my u and v
grids?

-kevin.



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Šand this afternoon, shortly after I sent this email, my test cases for
this approach abruptly stopped functioning. Whoops. So y'all may want to
hold off on this.
(I thought it looked too easyŠ)

Been that kind of day. :)
-jo

On 7/2/13 11:57 AM, "Valentine Cooper, Jo"
<Jo....@na...> wrote:

>Ran into a bug this morning with draggable annotations. It would seem that
>finalize_offset() forcibly overrides the annotation's textcoords status to
>"axes fraction" so it can set the coordinates properly. That's all well
>and good, but if you were using some text coordinates system other than
>"axes fraction" (say, for example, "data"), this can cause fun side
>effects such as annotations that used to pan around with the rest of the
>graph suddenly being frozen in place. :(
>
>Attached is a patch to restore the old textcoords mode in
>finalize_offset(). All it does  is save the old textcoords mode before
>making the change to "axes fraction" and restores it afterwards.
>
>Hope this helps!
>-jo
>
>

[Apologies for cross-posting]

The matplotlib developers want to hear from you!

We are conducting a user survey to determine how and where matplotlib is 
being used in order to focus its further development.

This should only take a couple of minutes.  To fill it out, visit:

https://docs.google.com/spreadsheet/viewform?fromEmail=true&formkey=dHpQS25pcTZIRWdqX0pNckNSU01sMHc6MQ 
<https://docs.google.com/spreadsheet/viewform?fromEmail=true&formkey=dHpQS25pcTZIRWdqX0pNckNSU01sMHc6MQ>

Please forward to your colleagues, particularly those who don't read 
these mailing lists.

Cheers,
Michael Droettboom, and the matplotlib team

Ran into a bug this morning with draggable annotations. It would seem that
finalize_offset() forcibly overrides the annotation's textcoords status to
"axes fraction" so it can set the coordinates properly. That's all well
and good, but if you were using some text coordinates system other than
"axes fraction" (say, for example, "data"), this can cause fun side
effects such as annotations that used to pan around with the rest of the
graph suddenly being frozen in place. :(

Attached is a patch to restore the old textcoords mode in
finalize_offset(). All it does  is save the old textcoords mode before
making the change to "axes fraction" and restores it afterwards.

Hope this helps!
-jo

On 07/02/2013 10:04 AM, Jason Grout wrote:
> On 7/1/13 9:33 AM, Michael Droettboom wrote:
>> SciPy 2013 was a great success.  I didn't get good headcount at the
>> matplotlib BOF, but it was a good number, and we had 15 participants at
>> various points during the sprints.  It was nice to see the diversity of
>> experience with matplotlib at the sprints, and I hope we oldtimers were
>> helpful to the newtimers getting started so they can continue to
>> contribute in the future.  It was also great to put some faces to many
>> of the talented names I've been seeing on github and the mailing list
>> lately.
>>
> On a slightly different, but related topic: is there any chance the
> entries (or at least the winning entries) to the plotting contest could
> be posted online?
>
My understanding is that they will be posted soon, along with the slides 
and other materials from the other papers.

For the impatient, they are in this git repo:

https://github.com/scipy/scipy2013_talks

Mike

On Tue, Jul 2, 2013 at 9:04 AM, Jason Grout <jas...@cr...>wrote:

> On 7/1/13 9:33 AM, Michael Droettboom wrote:
> > SciPy 2013 was a great success.  I didn't get good headcount at the
> > matplotlib BOF, but it was a good number, and we had 15 participants at
> > various points during the sprints.  It was nice to see the diversity of
> > experience with matplotlib at the sprints, and I hope we oldtimers were
> > helpful to the newtimers getting started so they can continue to
> > contribute in the future.  It was also great to put some faces to many
> > of the talented names I've been seeing on github and the mailing list
> > lately.
> >
>
> On a slightly different, but related topic: is there any chance the
> entries (or at least the winning entries) to the plotting contest could
> be posted online?
>

Yes, We'll put try to put these on the conference website at the very least.

Be Well
Anthony


>
> Thanks,
>
> Jason
>
>
>
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On 7/1/13 9:33 AM, Michael Droettboom wrote:
> SciPy 2013 was a great success.  I didn't get good headcount at the
> matplotlib BOF, but it was a good number, and we had 15 participants at
> various points during the sprints.  It was nice to see the diversity of
> experience with matplotlib at the sprints, and I hope we oldtimers were
> helpful to the newtimers getting started so they can continue to
> contribute in the future.  It was also great to put some faces to many
> of the talented names I've been seeing on github and the mailing list
> lately.
>

On a slightly different, but related topic: is there any chance the 
entries (or at least the winning entries) to the plotting contest could 
be posted online?

Thanks,

Jason

This is a constant source of confusion.  The colorbar object should be
thought of as just another subaxes.  To get the ticks, you want the ticks
from the colorbar's yaxis or xaxis object accordingly.  Of course, I could
have sworn we added a helper function for this at some point, but I could
be wrong.

I hope that helps!
Ben Root


On Tue, Jul 2, 2013 at 5:43 AM, Chao YUE <cha...@gm...> wrote:

> Dear all matplotlib users,
>
> I found there is not a get_ticks method available for colorbar instance,
> how could I quick get the ticks of a colorbar?
>
> thanks,
>
> Chao
> --
>
> ***********************************************************************************
> Chao YUE
> Laboratoire des Sciences du Climat et de l'Environnement (LSCE-IPSL)
> UMR 1572 CEA-CNRS-UVSQ
> Batiment 712 - Pe 119
> 91191 GIF Sur YVETTE Cedex
> Tel: (33) 01 69 08 29 02; Fax:01.69.08.77.16
>
> ************************************************************************************
>
>
> ------------------------------------------------------------------------------
> This SF.net email is sponsored by Windows:
>
> Build for Windows Store.
>
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> Mat...@li...
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>
>

There is the "set_over" and "set_under" members of a colormap, and the
plt.colorbar() function takes an "extend='min'" argument to add an extra
color at the beginning of the colorbar. Setting "extendrect=True", the
added color will be rectangular instead of triangular.

Hopefully that helps.

Cheers,
Ben Root



On Tue, Jul 2, 2013 at 6:14 AM, Chao YUE <cha...@gm...> wrote:

> One way I could think of is to make two contingent mat.axes.Axes,
> with a smaller one setting as white backgroud, and the other bigger on
> holding the colorbar. Is there some better way?
>
> Chao
>
>
> On Tue, Jul 2, 2013 at 12:12 PM, Chao YUE <cha...@gm...> wrote:
>
>> Dear all,
>>
>> Does anyone have similar experience that to make a colorbar
>> starting from a different color in the colormap? for example, to
>> denote the region with invalid data. I attahced a figure to show
>> what I would like to have, the withe region in the colorbar in the
>> attahced figure shows no data.
>>
>> thanks a lot for any help,
>>
>> best,
>>
>> Chao
>>
>> --
>>
>> ***********************************************************************************
>> Chao YUE
>> Laboratoire des Sciences du Climat et de l'Environnement (LSCE-IPSL)
>> UMR 1572 CEA-CNRS-UVSQ
>> Batiment 712 - Pe 119
>> 91191 GIF Sur YVETTE Cedex
>> Tel: (33) 01 69 08 29 02; Fax:01.69.08.77.16
>>
>> ************************************************************************************
>>
>
>
>
> --
>
> ***********************************************************************************
> Chao YUE
> Laboratoire des Sciences du Climat et de l'Environnement (LSCE-IPSL)
> UMR 1572 CEA-CNRS-UVSQ
> Batiment 712 - Pe 119
> 91191 GIF Sur YVETTE Cedex
> Tel: (33) 01 69 08 29 02; Fax:01.69.08.77.16
>
> ************************************************************************************
>
>
> ------------------------------------------------------------------------------
> This SF.net email is sponsored by Windows:
>
> Build for Windows Store.
>
> http://p.sf.net/sfu/windows-dev2dev
> _______________________________________________
> Matplotlib-users mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>
>

One way I could think of is to make two contingent mat.axes.Axes,
with a smaller one setting as white backgroud, and the other bigger on
holding the colorbar. Is there some better way?

Chao

On Tue, Jul 2, 2013 at 12:12 PM, Chao YUE <cha...@gm...> wrote:

> Dear all,
>
> Does anyone have similar experience that to make a colorbar
> starting from a different color in the colormap? for example, to
> denote the region with invalid data. I attahced a figure to show
> what I would like to have, the withe region in the colorbar in the
> attahced figure shows no data.
>
> thanks a lot for any help,
>
> best,
>
> Chao
>
> --
>
> ***********************************************************************************
> Chao YUE
> Laboratoire des Sciences du Climat et de l'Environnement (LSCE-IPSL)
> UMR 1572 CEA-CNRS-UVSQ
> Batiment 712 - Pe 119
> 91191 GIF Sur YVETTE Cedex
> Tel: (33) 01 69 08 29 02; Fax:01.69.08.77.16
>
> ************************************************************************************
>



-- 
***********************************************************************************
Chao YUE
Laboratoire des Sciences du Climat et de l'Environnement (LSCE-IPSL)
UMR 1572 CEA-CNRS-UVSQ
Batiment 712 - Pe 119
91191 GIF Sur YVETTE Cedex
Tel: (33) 01 69 08 29 02; Fax:01.69.08.77.16
************************************************************************************

Dear all,

Does anyone have similar experience that to make a colorbar
starting from a different color in the colormap? for example, to
denote the region with invalid data. I attahced a figure to show
what I would like to have, the withe region in the colorbar in the
attahced figure shows no data.

thanks a lot for any help,

best,

Chao

-- 
***********************************************************************************
Chao YUE
Laboratoire des Sciences du Climat et de l'Environnement (LSCE-IPSL)
UMR 1572 CEA-CNRS-UVSQ
Batiment 712 - Pe 119
91191 GIF Sur YVETTE Cedex
Tel: (33) 01 69 08 29 02; Fax:01.69.08.77.16
************************************************************************************

Dear all matplotlib users,

I found there is not a get_ticks method available for colorbar instance,
how could I quick get the ticks of a colorbar?

thanks,

Chao
-- 
***********************************************************************************
Chao YUE
Laboratoire des Sciences du Climat et de l'Environnement (LSCE-IPSL)
UMR 1572 CEA-CNRS-UVSQ
Batiment 712 - Pe 119
91191 GIF Sur YVETTE Cedex
Tel: (33) 01 69 08 29 02; Fax:01.69.08.77.16
************************************************************************************

On 1 July 2013 13:40, zetah <ot...@hu...> wrote:

> Hi,
>
> I have set of points in a plane and make triplot:
>
>     subplot(121)
>     plot(points[:,0], points[:,1], 'o')
>     title('Set of points')
>     subplot(122)
>     triplot(points[:,0], points[:,1])
>     title('Triangulation')
>
> result: http://i.imgur.com/1LG4fxC.png
>
> Does anyone know how to extract just the lines describing each
> circumscribed circle in this example?
> Perhaps by using Delaunay from scipy.spatial?
>
> Just to inform you, I want to do this through triangulation and above
> example is trivial that can be solved differently, while real problem
> doesn't contain circles...
>

You need to use a matplotlib.tri.Triangulation (your use of triplot does
this for you behind the scenes anyway), something like:

import matplotlib.tri as mtri
triang = mtri.Triangulation(xpoints, ypoints)

Now triang.triangles is an array of integers of shape (?, 3) such that
triang.triangles[i,:] are the three indices of the points that comprise
triangle i.  You will need to use these to determine the information you
want.  The triplot example (
http://matplotlib.org/examples/pylab_examples/triplot_demo.html) does
something similar, identifying which triangles are within a particular
circle; I guess in your case a simple approach would be to test if the
distance from the centre of each triangle edge to your circle of interest
is below some threshold or not.

Incidentally, if you have a Triangulation object then subsequent calls to
functions like triplot can be of the form triplot(triang), which will be
faster than repeated calls to triplot(xpoints, ypoints) as in the latter
case a separate Delaunay triangulation needs to be performed for each
triplot call.

Ian

William Ray Wing wrote
> On Jul 1, 2013, at 1:42 PM, psb1967 <

> psb67@

> > wrote:
> 
> 
> Suresh,  I think the most likely reason no one has answered is that the
> intersection of the set of matplotlib experts and the set of people who
> know what Bollinger bands are is too close to zero.  I'm a beginner at
> matplotlib, but I do know what Bollinger bands are, and I'd suggest your
> best approach is to take a look at the matplotlib demo gallery here:  
> 
> http://matplotlib.org/examples
> 
> in particular, study the code for the fifth example from the top here: 
> http://matplotlib.org/examples/pylab_examples/plotfile_demo.html
> 
> which implements a plot of Open, High. Low, and Closing prices.  I'm
> assuming you know enough math to implement a Bollinger band version of a
> moving average, and can just substitute it for the code that plots the
> extra lines on the example.
> 
> Good luck,
> Bill

Hi Bill,

I am truly overwhelmed to see the kind of efforts taken to guide when one
requires guidance, esp. the fresh programmers. One of the things that I
learned when no one responds with a specific answer but shown the direction
is that I am given an opportunity to learn and work  by myself. I really
appreciate your time and will start working on the example you have cited.

In fact, I did get a complete Bollinger bands script however, I will start
working on the line you have shown; it may open up new avenues. 

Regards.

Suresh



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Hi all,

after John's untimely passing we had a memorial service in Chicago,
but only a few on these lists were able to attend. At last week's
scipy conference I read a slightly edited version of the eulogy from
that memorial service, and I figured some of you might be interested
if you missed the conference:

http://blog.fperez.org/2013/07/in-memoriam-john-d-hunter-iii-1968-2012.html

Cheers,

f

--
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fperez.net-at-gmail: mailing lists only (I ignore this when swamped!)
fernando.perez-at-berkeley: contact me here for any direct mail

On Jul 1, 2013, at 1:42 PM, psb1967 <ps...@ho...> wrote:

> Hi Ben,
> 
> 
> Benjamin Root-2 wrote
>> On Sun, Jun 23, 2013 at 6:29 AM, psb1967 &lt;
> 
>> psb67@
> 
>> &gt; wrote:
>> 
>> 
>>> 
>> Since nobody has replied, I would suggest asking your question on the
>> scipy
>> users list, which is more geared towards implementation of various
>> algorithms. The matplotlib mailing list mostly deals with plotting
>> questions.  When you need help with plotting your results, let us know!
>> 
>> Cheers!
>> Ben Root
> 
> May be it was my mistake posting a wrong request, without properly
> understanding the nature of this elite site, nevertheless, I am grateful for
> your taking time to reply and guide me in the proper direction.
> 
> I will give it a try with scipy user list.
> 
> Regards
> 
> Suresh
> 
> 

Suresh,  I think the most likely reason no one has answered is that the intersection of the set of matplotlib experts and the set of people who know what Bollinger bands are is too close to zero.  I'm a beginner at matplotlib, but I do know what Bollinger bands are, and I'd suggest your best approach is to take a look at the matplotlib demo gallery here:  

http://matplotlib.org/examples

in particular, study the code for the fifth example from the top here:  http://matplotlib.org/examples/pylab_examples/plotfile_demo.html

which implements a plot of Open, High. Low, and Closing prices.  I'm assuming you know enough math to implement a Bollinger band version of a moving average, and can just substitute it for the code that plots the extra lines on the example.

Good luck,
Bill