matplotlib-users Mailing List for matplotlib

On Wed, Jul 29, 2009 at 4:38 AM, John Hunter <jd...@gm...> wrote:
> On Wed, Jul 29, 2009 at 1:01 AM, Art<gre...@gm...> wrote:
> > I have a scatter plot that requires some time to render. The horizontal
> axis
> > is time. Currently, I generate the full scatter plot each time and draw a
> > axvline to indicate the progress of time, save the file as a png for each
> > time, and generate a movie for all time frames. The scatter plot portion
> > doesn't change, just the vertical line.
> >
> > I was wondering if there was a way to speed this up, to generate the
> scatter
> > plot once and then overlay it with a moving axvline. I would still have
> to
> > save the png frame by frame, but the most expensive step by far is
> > replotting the scatter plot over and over.
>
> This is what the animation/blit api is designed to do:
>
> http://www.scipy.org/Cookbook/Matplotlib/Animations
>
> scipy.org appears down right now, so you may need to try again later.
> See also these mpl examples:
>
> http://matplotlib.sourceforge.net/search.html?q=codex+blit
>
> JDH
>
Thanks John. That made things more than an order of magnitude faster. It's
very impressive.
My bottleneck now is actually saving the pngs for mencoder to make into an
avi (as with the movie_demo example on your site) using savefig. Do you also
know of an alternative way of generating an avi of the animation? My
animation has about 9000 frames.
Thanks,
Art.

Hello,
thru data.gov, there are several shapefile archives available, in a zip format.
Do someone believe it worths to support this kind of "distribution" of
shp or we'd like still to have the zip unzip'ed first and the
readshapefile() the resulting file?
Regards,
-- 
Sandro Tosi (aka morph, morpheus, matrixhasu)
My website: http://matrixhasu.altervista.org/
Me at Debian: http://wiki.debian.org/SandroTosi

Hi everyone,
I am trying to build the latest svn trunk version of MPL on OS X 10.5. I am
getting the following error:
ld: in /Developer/SDKs/MacOSX10.4u.sdk/usr/local/lib/libPng.dylib, file is
not of required architecture for architecture ppc
After googling quite a bit, this seems to be quite a common problem.
However, I could still not find an unambiguous solution. I have build
libpng from source on my machine. The file output is:
laserson@hobbes:/usr/local/lib$ file libpng*
libpng.3.dylib: Mach-O dynamically linked shared library i386
libpng.a: current ar archive random library
libpng.dylib: Mach-O dynamically linked shared library i386
libpng.la: ASCII English text
libpng12.0.dylib: Mach-O dynamically linked shared library i386
libpng12.a: current ar archive random library
libpng12.dylib: Mach-O dynamically linked shared library i386
libpng12.la: ASCII English text
It appears that the compiler expects that libpng will also have libraries
for ppc. What do I do? Do I need to rebuild libpng to be universal? (How
is this done?) Or do I need to somehow tell distutils to build MPL only for
i386? (How is thid done?)
Below is the full build output. Thanks for your help!
Uri
============================================================================
BUILDING MATPLOTLIB
 matplotlib: 0.98.6svn
 python: 2.5.2 |EPD with Py2.5 4.0.30002 | (r252:60911, Oct
 15 2008, 16:58:38) [GCC 4.0.1 (Apple Computer, Inc.
 build 5370)]
 platform: darwin
REQUIRED DEPENDENCIES
 numpy: 1.3.0
 freetype2: 9.20.3
OPTIONAL BACKEND DEPENDENCIES
 libpng: 1.2.34
 Tkinter: Tkinter: 50704, Tk: 8.4, Tcl: 8.4
 wxPython: 2.8.7.1
 * WxAgg extension not required for wxPython >= 2.8
 Gtk+: no
 * Building for Gtk+ requires pygtk; you must be able
 * to "import gtk" in your build/install environment
 Mac OS X native: yes
 Qt: no
 Qt4: no
 Cairo: no
OPTIONAL DATE/TIMEZONE DEPENDENCIES
 datetime: present, version unknown
 dateutil: 1.4
 pytz: 2008c
OPTIONAL USETEX DEPENDENCIES
 dvipng: 1.11
 ghostscript: 8.62
 latex: 3.1415926
[Edit setup.cfg to suppress the above messages]
============================================================================
pymods ['pylab']
packages ['matplotlib', 'matplotlib.backends', 'matplotlib.projections',
'mpl_toolkits', 'mpl_toolkits.mplot3d', 'mpl_toolkits.axes_grid',
'matplotlib.sphinxext', 'matplotlib.numerix', 'matplotlib.numerix.mlab', '
matplotlib.numerix.ma', 'matplotlib.numerix.linear_algebra',
'matplotlib.numerix.random_array', 'matplotlib.numerix.fft',
'matplotlib.delaunay']
running build
running build_py
copying lib/matplotlib/mpl-data/matplotlibrc ->
build/lib.macosx-10.3-i386-2.5/matplotlib/mpl-data
copying lib/matplotlib/mpl-data/matplotlib.conf ->
build/lib.macosx-10.3-i386-2.5/matplotlib/mpl-data
running build_ext
building 'matplotlib.backends._tkagg' extension
g++ -arch i386 -arch ppc -isysroot /Developer/SDKs/MacOSX10.4u.sdk -g
-bundle -undefined dynamic_lookup
build/temp.macosx-10.3-i386-2.5/src/agg_py_transforms.o
build/temp.macosx-10.3-i386-2.5/src/_tkagg.o
build/temp.macosx-10.3-i386-2.5/CXX/cxx_extensions.o
build/temp.macosx-10.3-i386-2.5/CXX/cxxsupport.o
build/temp.macosx-10.3-i386-2.5/CXX/IndirectPythonInterface.o
build/temp.macosx-10.3-i386-2.5/CXX/cxxextensions.o -L/usr/local/lib
-L/usr/lib -L/usr/local/lib -L/usr/lib -lstdc++ -lm -lfreetype -lz -lstdc++
-lm -o build/lib.macosx-10.3-i386-2.5/matplotlib/backends/_tkagg.so
-framework Tcl -framework Tk
ld: warning in
/Developer/SDKs/MacOSX10.4u.sdk/usr/local/lib/libfreetype.dylib, file is not
of required architecture
ld: in /Developer/SDKs/MacOSX10.4u.sdk/usr/local/lib/libPng.dylib, file is
not of required architecture for architecture ppc
collect2: ld returned 1 exit status
lipo: can't open input file:
/var/folders/Ln/LnyDoYbfGd8tkbnxDCl7Zk+++TI/-Tmp-//ccHqlli7.out (No such
file or directory)
error: command 'g++' failed with exit status 1
-- 
Uri Laserson
PhD Candidate, Biomedical Engineering
Harvard Medical School (Genetics)
Massachusetts Institute of Technology (Mathematics)
phone +1 917 742 8019
las...@mi...

Michael Droettboom wrote:
> This is a long-standing known issue with the contour code. The 
> contouring library we are using (in cntr.c) was written for a graphics 
> library that did not support compound paths, so to draw a donut-shaped 
> objects it creates "cut paths" from the inner to outer edge. A number 
> of the matplotlib developers have taken stabs at changing this behavior 
> over the years, but it is a very opaque chunk of code, and none of us 
> have managed it without introducing new more serious errors. A fresh 
> set of eyes may be able to sort it out, and we do have compound path 
> support in all backends (save the mostly obsolete Gdk) now. Replacing 
> the contouring code with something else that is license-compatible is 
> also an option, but I wasn't able to find anything suitable last time I 
> looked (which was a long time ago now).
I have been looking about every 6 months for years, with absolutely no 
success. There are remarkably few filled-contouring codes (or detailed 
algorithm descriptions) out there, under any license. Note also that 
the code Matlab uses (or at least used a long time ago when I last 
looked) handles the problem by layering the contour patches, not by 
leaving holes, so it is an example of a class of algorithms that would 
not work with non-unit alpha. I have also thought a bit about 
manipulating the paths generated by the present code to remove the cuts, 
or manipulating the non-filled contour output to generate patch 
boundaries, but I haven't gone into it deeply. I suspect it would 
quickly become very complicated. And, on top of all that, even if we 
solved the cut problem, there would still be backend-dependent artifacts 
involved in rendering the boundaries.
Eric
> 
> Cheers,
> Mike
> 
> Joseph Smidt wrote:
>> I am making contourf plots with some transparency as I want to
>> eventually overlay such plots. When I plot such plots I see artifacts
>> or lines that shouldn't be there as seen here:
>> http://josephsmidt.googlepages.com/ex.png
>>
>> Is this a bug or am I plotting incorrectly? My script is here:
>> http://josephsmidt.googlepages.com/plotex.py and the data needed for
>> the plot is here: http://josephsmidt.googlepages.com/exCHI.txt
>>
>> However, the relevant part of the code for plotting I'll just cut and
>> paste here:
>>
>> levels = [x0, x1, x2, x3]
>> contourf(Y,X,transpose(CHI),levels,alpha=0.7)
>> show()
>>
>> Thanks.
>>
>> Joseph Smidt
>>
>>
>> 
> 

Thanks a lot. The code you mentioned:
cs = contourf(Y,X,transpose(CHI),levels,alpha=0.7)
for c in cs.collections:
 c.set_edgecolors('none')
 worked great and the extra lines are gone.
 Joseph Smidt
PS. Good luck with this issue. I'd help but I'm not that good.
-- 
------------------------------------------------------------------------
Joseph Smidt <jos...@gm...>
Physics and Astronomy
4129 Frederick Reines Hall
Irvine, CA 92697-4575
Office: 949-824-3269

Joseph Smidt wrote:
> I am making contourf plots with some transparency as I want to
> eventually overlay such plots. When I plot such plots I see artifacts
> or lines that shouldn't be there as seen here:
> http://josephsmidt.googlepages.com/ex.png
> 
> Is this a bug or am I plotting incorrectly? My script is here:
> http://josephsmidt.googlepages.com/plotex.py and the data needed for
> the plot is here: http://josephsmidt.googlepages.com/exCHI.txt
> 
> However, the relevant part of the code for plotting I'll just cut and
> paste here:
> 
> levels = [x0, x1, x2, x3]
> contourf(Y,X,transpose(CHI),levels,alpha=0.7)
> show()
> 
> Thanks.
> 
> Joseph Smidt
> 
> 
This is a problem with two parts: first, the filled-contour algorithm 
creates singly-connected patches, so cuts are required (the horizontal 
lines); second, depending on whether edges are stroked and on the 
antialias setting, these cuts, and the boundaries between regions, can 
show up as artifacts when rendered. The rendering problem can be 
backend-dependent.
When I make a contourf plot using the agg backend (which is presumably 
what you are using to make the png file--either directly or indirectly 
via an interactive backend), I am not seeing the artifacts, so I think 
the default settings in svn are good for agg rendering with alpha. My 
guess is that you are using a version of mpl with different settings. We 
have struggled with this problem, trying different combinations of 
settings, for a long time. There doesn't seem to be a formula that works 
for all backends and all alpha values.
I suspect that in the version of mpl you are using, the patch edges are 
being stroked. As a workaround, try this:
cs = contourf(Y,X,transpose(CHI),levels,alpha=0.7)
for c in cs.collections:
 c.set_edgecolors(['none'])
Eric

Hi,
2009年7月29日 Jae-Joon Lee <lee...@gm...>:
> On Tue, Jul 28, 2009 at 9:11 AM, Roland Koebler<r.k...@ya...> wrote:
[cut]
>> Any ideas?
>>
>
> http://matplotlib.sourceforge.net/examples/animation/animation_blit_gtk2.html
>
> The above example does something similar to (b).
> It saves the previous plot (only axes area is saved) as a bitmap. In
> next run, it restores the saved bitmap after shifting. And then draw
> only the new data points.
>
> The example requires the svn version of matplotlib.
I have attached another example of blit animation that does NOT
require the svn version of MPL.
 Antonio

This is a long-standing known issue with the contour code. The 
contouring library we are using (in cntr.c) was written for a graphics 
library that did not support compound paths, so to draw a donut-shaped 
objects it creates "cut paths" from the inner to outer edge. A number 
of the matplotlib developers have taken stabs at changing this behavior 
over the years, but it is a very opaque chunk of code, and none of us 
have managed it without introducing new more serious errors. A fresh 
set of eyes may be able to sort it out, and we do have compound path 
support in all backends (save the mostly obsolete Gdk) now. Replacing 
the contouring code with something else that is license-compatible is 
also an option, but I wasn't able to find anything suitable last time I 
looked (which was a long time ago now).
Cheers,
Mike
Joseph Smidt wrote:
> I am making contourf plots with some transparency as I want to
> eventually overlay such plots. When I plot such plots I see artifacts
> or lines that shouldn't be there as seen here:
> http://josephsmidt.googlepages.com/ex.png
>
> Is this a bug or am I plotting incorrectly? My script is here:
> http://josephsmidt.googlepages.com/plotex.py and the data needed for
> the plot is here: http://josephsmidt.googlepages.com/exCHI.txt
>
> However, the relevant part of the code for plotting I'll just cut and
> paste here:
>
> levels = [x0, x1, x2, x3]
> contourf(Y,X,transpose(CHI),levels,alpha=0.7)
> show()
>
> Thanks.
>
> Joseph Smidt
>
>
> 
-- 
Michael Droettboom
Science Software Branch
Operations and Engineering Division
Space Telescope Science Institute
Operated by AURA for NASA

I am making contourf plots with some transparency as I want to
eventually overlay such plots. When I plot such plots I see artifacts
or lines that shouldn't be there as seen here:
http://josephsmidt.googlepages.com/ex.png
 Is this a bug or am I plotting incorrectly? My script is here:
http://josephsmidt.googlepages.com/plotex.py and the data needed for
the plot is here: http://josephsmidt.googlepages.com/exCHI.txt
However, the relevant part of the code for plotting I'll just cut and
paste here:
levels = [x0, x1, x2, x3]
contourf(Y,X,transpose(CHI),levels,alpha=0.7)
show()
 Thanks.
 Joseph Smidt
-- 
------------------------------------------------------------------------
Joseph Smidt <jos...@gm...>
Physics and Astronomy
4129 Frederick Reines Hall
Irvine, CA 92697-4575
Office: 949-824-3269

n Tue, Jul 28, 2009 at 8:11 AM, Roland Koebler <r.k...@ya...> wrote:
> Hi,
>
> I've got some performance problems with matplotlib, and would like to
> ask if you know any way I can make it faster.
>
> If there is no such way, I have to decide to (a) either enhance matplotlib
> or (b) write my own plotting-library.
> (I'm currently using matplotlib to plot data "live" on the screen,
> including
> animation, scrolling, zoom+pam, custom scales (to zoom out some part of the
> plot), and multiple X-/Y-Axes. I therefore already wrote some wrappers
> around
> matplotlib to implement some of these features.)
>
> In detail:
> - I have a figure containing some plots (lines).
> - About every second I "update" the plot:
> - Add a few points to the lines.
> (=add point to an array and call set_data(array))
> - Scroll the plot, so that the latest point is on the right of the plot.
> Older points disappear on the left side of the plot.
> (=set_xaxis() + draw())
> - I'm using GtkAgg, incl. animation, (re)storing the background, drawing
> the artists and blit.
> (canvas.restore_region(...), ax.draw_artist(...), canvas.blit(bbox))
>
> This works as long as the plot only contains a few points,
> although 2 figures + 5-10 lines per figure and an update every 0.5 s
> already consumes about 10-20% CPU (on a 1.4 GHz Pentium).
> By the way: Is this speed normal, or is matplotlib usually faster?
>
> But as soon as the plot contains *many* points (several 10000 up to
> several 100000), the plotting becomes terribly slow -- up to 30s
> per update and more!
>
> Do you know any way to make this faster?
>
> My ideas are:
> - Since I only add points to the *right* of the lines, I could reduce the
> number of points, by first removing all points which are outside of
> the current visible plotting-window from my array, and then calling
> set_data() with the reduced array.
> - This unfortunately wouldn't reduce the number of points in very dense
> plots. It would be possible to (a) replace several points which all
> result in the same plotted point by a single point or (b) cache the
> plotted points e.g. on pixel-level. I think (b) would probably require
> to write a new backend.
There might be some performance improvement to be had depending on how you
are adding the additional points to the array. Seeing a complete, minimal
of the code showing the performance problem would be needed, since it's the
details that matter in this case.
Ryan
-- 
Ryan May
Graduate Research Assistant
School of Meteorology
University of Oklahoma
Sent from Norman, Oklahoma, United States

The documentation for scatter command is out of date unfortunately.
You need to use "scatterpoints" keyword.
http://www.nabble.com/legend-bug--td22466216.html#a22466216
-JJ
On Mon, Jul 27, 2009 at 3:44 PM, per freem<per...@gm...> wrote:
> Hi all
>
> i am making a scatter plot and want to label one of the points in the
> legend. i run
>
> scatter([x], [y], ..., label="mylabel")
>
> and then run legend as follows
>
> plt.legend(loc='lower right', numpoints=1, pad=0.01, labelsep=.01,
> handlelen=.05)
>
> i set numpoints=1 because i want it to show just one point and then its
> label. however, this always generates a legend with three points, i.e.
>
> o o o  my label
>
> rather than
>
> o mylabel
>
> does anyone know how to fix this? thank you.
>
>
> ------------------------------------------------------------------------------
>
> _______________________________________________
> Matplotlib-users mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>
>

It looks like SourceForge has been making some pretty major changes to 
the file download system. That part of SourceForge was always the most 
confusing and frustrating part of the system. I just went in and 
re-specified the default files, and it appears to be working now. 
Please report your experiences on Windows and Mac, since I did not test 
those platforms.
Mike
Josh Hemann wrote:
> I downloaded it also yesterday thinking I was getting a newer (than 0.98.5.3)
> version of matplotlib. Definitely misleading, so thanks for posting this
> thread.
>
> Josh
>
> Kaushik Ghose-3 wrote:
> 
>> Hi All,
>>
>> I was downloading matplotlib on a windows machine and the sourceforge site 
>> (http://sourceforge.net/projects/matplotlib/) showed me basemap as the
>> default 
>> download (instead of the latest matplotlib). On Mac the default download
>> shows 
>> correctly as matplotlib.
>>
>> This is some autodetection from sourceforge, so I don't know if it is a
>> sitewide 
>> problem, or it can be configured from the project page. Just to let the
>> admins know.
>>
>> Best
>> -Kaushik
>>
>> ------------------------------------------------------------------------------
>> 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
>>
>>
>> 
>
> 
-- 
Michael Droettboom
Science Software Branch
Operations and Engineering Division
Space Telescope Science Institute
Operated by AURA for NASA

I downloaded it also yesterday thinking I was getting a newer (than 0.98.5.3)
version of matplotlib. Definitely misleading, so thanks for posting this
thread.
Josh
Kaushik Ghose-3 wrote:
> 
> Hi All,
> 
> I was downloading matplotlib on a windows machine and the sourceforge site 
> (http://sourceforge.net/projects/matplotlib/) showed me basemap as the
> default 
> download (instead of the latest matplotlib). On Mac the default download
> shows 
> correctly as matplotlib.
> 
> This is some autodetection from sourceforge, so I don't know if it is a
> sitewide 
> problem, or it can be configured from the project page. Just to let the
> admins know.
> 
> Best
> -Kaushik
> 
> ------------------------------------------------------------------------------
> 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
> 
> 
-- 
View this message in context: http://www.nabble.com/Sourceforge-download-page-shows-basemap-as-default-download-on-windows-tp24711475p24722906.html
Sent from the matplotlib - users mailing list archive at Nabble.com.

scatter() currently does not support arbitrary path as its marker. The
current marker customization is limited to what can be described by
RegularPolyCollection and etc. And the crosshair marker do not fit in
to this category.
I'm attaching a snippet of a code I have been using for an exactly
same purpose as yours (to mark stars).
I hope this is also useful for you.
It provide a scatter-like function that takes arbitrary path
(PathPatch as a matter of fact).
It would not be difficult to extend the matplotlib's scatter function
to support an arbitrary path. I may give it a try later this week.
Regards,
-JJ
On Tue, Jul 28, 2009 at 5:57 PM, Paul Ray<pau...@nr...> wrote:
> Hi,
>
> I see that scatter() has a variety of different symbols that you can
> choose from, and even a way to create your own custom markers.
> However, I can't figure out how to make a crosshair symbol (a plus
> with non-touching lines) as my marker, which I'd like to use to show
> the location of a star on an underlying image without obscuring the
> star itself.
>
> Graphically, I'd like a marker symbol that looks like this...
>
>     |
>     |
>     |
>
> =======   =======
>
>     |
>     |
>     |
>
> Does anyone know how to pull this off?
>
> Thanks!
>
> -- Paul
>
>
> ------------------------------------------------------------------------------
> 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 Tue, Jul 28, 2009 at 9:11 AM, Roland Koebler<r.k...@ya...> wrote:
> Hi,
>
> I've got some performance problems with matplotlib, and would like to
> ask if you know any way I can make it faster.
>
> If there is no such way, I have to decide to (a) either enhance matplotlib
> or (b) write my own plotting-library.
> (I'm currently using matplotlib to plot data "live" on the screen, including
> animation, scrolling, zoom+pam, custom scales (to zoom out some part of the
> plot), and multiple X-/Y-Axes. I therefore already wrote some wrappers around
> matplotlib to implement some of these features.)
>
> In detail:
> - I have a figure containing some plots (lines).
> - About every second I "update" the plot:
> - Add a few points to the lines.
>  (=add point to an array and call set_data(array))
> - Scroll the plot, so that the latest point is on the right of the plot.
>  Older points disappear on the left side of the plot.
>  (=set_xaxis() + draw())
> - I'm using GtkAgg, incl. animation, (re)storing the background, drawing
> the artists and blit.
> (canvas.restore_region(...), ax.draw_artist(...), canvas.blit(bbox))
>
> This works as long as the plot only contains a few points,
> although 2 figures + 5-10 lines per figure and an update every 0.5 s
> already consumes about 10-20% CPU (on a 1.4 GHz Pentium).
> By the way: Is this speed normal, or is matplotlib usually faster?
>
> But as soon as the plot contains *many* points (several 10000 up to
> several 100000), the plotting becomes terribly slow -- up to 30s
> per update and more!
>
> Do you know any way to make this faster?
>
> My ideas are:
> - Since I only add points to the *right* of the lines, I could reduce the
> number of points, by first removing all points which are outside of
> the current visible plotting-window from my array, and then calling
> set_data() with the reduced array.
> - This unfortunately wouldn't reduce the number of points in very dense
> plots. It would be possible to (a) replace several points which all
> result in the same plotted point by a single point or (b) cache the
> plotted points e.g. on pixel-level. I think (b) would probably require
> to write a new backend.
>
> Any ideas?
>
http://matplotlib.sourceforge.net/examples/animation/animation_blit_gtk2.html
The above example does something similar to (b).
It saves the previous plot (only axes area is saved) as a bitmap. In
next run, it restores the saved bitmap after shifting. And then draw
only the new data points.
The example requires the svn version of matplotlib.
Regards,
-JJ
>
> regards,
> Roland
>
>
> ------------------------------------------------------------------------------
> 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
>

Have you seen this?
http://zunzun.com/
*"Online Curve Fitting and Surface Fitting Web Site*"
On Wed, Jul 29, 2009 at 6:16 AM, Bala subramanian <bal...@gm...
> wrote:
> Friends,
>
> I have to define two equations and fit my data on to it. could someone
> please give me some example on how to do curve fitting using matplotlib.
>
> Thanks,
> Bala
>
>
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Quoting Bala subramanian <bal...@gm...>:
> Friends,
> 
> I have to define two equations and fit my data on to it. could someone
> please give me some example on how to do curve fitting using matplotlib.
http://docs.scipy.org/doc/numpy/reference/generated/numpy.polyfit.html
(Matplotlib example at the bottom)
Cheers,
G
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Friends,
I have to define two equations and fit my data on to it. could someone
please give me some example on how to do curve fitting using matplotlib.
Thanks,
Bala

On Tue, Jul 28, 2009 at 10:27 PM, Kun Hong<kun...@uq...> wrote:
> Hi,
>
> I am new to matplotlib. Currently I have a need to change the subplot
> orders after the subplts have been added to a figure. I haven't found a
> way to do it easily. One of my solution is to keep an ordered list of
> the subplots and re-add them in the correct order. But this way, all the
> navigation information (zoom/pan) is lost. Another way I found is to
> get the positions (get_position method of Axes) of the subplot and
> then set the positions according to the new order, which is quite
> cumbersom. I am thinking if there is a similar method like add_subplot
> (that is, accepting new positional information of row, column, number
> instead of Bbox), it will be great. Does anyone know any better
> solution?
It should work to call ax.change_geometry on the existing subplot instances.
 http://matplotlib.sourceforge.net/api/axes_api.html#matplotlib.axes.SubplotBase.change_geometry
Haven't tested it for this use case, but I'm pretty sure it will do
what you want. Let me know!
JDH

On Wed, Jul 29, 2009 at 1:01 AM, Art<gre...@gm...> wrote:
> I have a scatter plot that requires some time to render. The horizontal axis
> is time. Currently, I generate the full scatter plot each time and draw a
> axvline to indicate the progress of time, save the file as a png for each
> time, and generate a movie for all time frames. The scatter plot portion
> doesn't change, just the vertical line.
>
> I was wondering if there was a way to speed this up, to generate the scatter
> plot once and then overlay it with a moving axvline. I would still have to
> save the png frame by frame, but the most expensive step by far is
> replotting the scatter plot over and over.
This is what the animation/blit api is designed to do:
http://www.scipy.org/Cookbook/Matplotlib/Animations
scipy.org appears down right now, so you may need to try again later.
See also these mpl examples:
http://matplotlib.sourceforge.net/search.html?q=codex+blit
JDH

On Wed, Jul 29, 2009 at 1:39 AM, 3togo<fre...@gm...> wrote:
>
> mlab.psd and pyplot.psd are different!!!!
The plotting command pyplot.psd scales the numbers in decibels (the dB
in the ylabel in pyplot.psd). mlab.psd just returns the unscaled
power. So in your example in subplot(3,1,3), call before plotting
 x = 10*np.log10(np.absolute(x))
JDH

#This program below do reveal that mlab.psd and pyplot.psd are different
http://www.nabble.com/file/p24713274/psd_testpng.png psd_testpng.png 
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.mlab as mlab
dt = np.pi / 100.
fs = 1. / dt
t = np.arange(0, 8, dt)
y = 10. * np.sin(2 * np.pi * 4 * t) + 5. * np.sin(2 * np.pi * 4.25 * t)
y = y + np.random.randn(*t.shape)
print "t=",t
print "y=",y
print "fs=",fs
#Plot the raw time series
fig = plt.figure()
fig.subplots_adjust(hspace=0.6, wspace=0.5)
#
ax = fig.add_subplot(3, 1, 1)
plt.title('Data')
ax.plot(t,y)
ax = fig.add_subplot(3, 1, 2)
plt.title('psd using pyplot')
ax.psd(y,Fs=fs,scale_by_freq=False)
ax = fig.add_subplot(3, 1, 3)
plt.title('psd using mlab')
x,y=mlab.psd(y,Fs=fs,scale_by_freq=False)
ax.plot(y,x)
plt.show()
Lewis, Ambrose J. wrote:
> 
> Hi All:
> 
> I'm trying to use the matplotlib psd function to plot some data. The
> result from MATLAB's pWelch function looks vastly different.
> 
> Any suggestions/recommendations would be greatly appreciated!
> 
> THANXS
> 
> amb
> 
> 
> 
> Here is the MATLAB code:
> 
> Fs = 13e6;
> 
> fid = fopen('C:\asp\roseRT\ics_output.bin', 'r', 'ieee-le');
> 
> s = fread(fid, [2, Inf], 'int32');
> 
> fclose(fid);
> 
> z = complex(s(2,:), s(1,:));
> 
> pwelch(z, [], [], [], Fs)
> 
> 
> 
> And here is the (hypothetically) equivalent Python/matplotlib code:
> 
> datatype = np.complex64
> 
> fd = open(self.filename, 'rb')
> 
> read_data = np.fromfile(file=fd, dtype=datatype)
> 
> Pxx,freqs = psd(read_data,Fs=13000000) 
> 
> self.axes.plot(freqs, 10*log10(Pxx) ) 
> 
> self.canvas.draw()
> 
> 
> 
> Ambrose Lewis
> 
> SAIC
> 
> 4001 N Fairfax Drive, Suite 400
> 
> Arlington, VA 22203
> 
> 703.558.2786
> 
> amb...@sa... 
> 
> 
> 
> 
> ------------------------------------------------------------------------------
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> 
-- 
View this message in context: http://www.nabble.com/psd-question...-tp21458898p24713274.html
Sent from the matplotlib - users mailing list archive at Nabble.com.

I have a scatter plot that requires some time to render. The horizontal axis
is time. Currently, I generate the full scatter plot each time and draw a
axvline to indicate the progress of time, save the file as a png for each
time, and generate a movie for all time frames. The scatter plot portion
doesn't change, just the vertical line.
I was wondering if there was a way to speed this up, to generate the scatter
plot once and then overlay it with a moving axvline. I would still have to
save the png frame by frame, but the most expensive step by far is
replotting the scatter plot over and over.
Thanks!

Hi,
I am new to matplotlib. Currently I have a need to change the subplot
orders after the subplts have been added to a figure. I haven't found a
way to do it easily. One of my solution is to keep an ordered list of
the subplots and re-add them in the correct order. But this way, all the
navigation information (zoom/pan) is lost. Another way I found is to 
get the positions (get_position method of Axes) of the subplot and 
then set the positions according to the new order, which is quite
cumbersom. I am thinking if there is a similar method like add_subplot
(that is, accepting new positional information of row, column, number
instead of Bbox), it will be great. Does anyone know any better
solution?
Also related to this, I need to add a subplot using the add_subplot
method of the Figure class, and update the previously added subplots
accordingly. For example, I add a subplot using add_subplot(1, 1, 1).
Then later, I need to add another subplot. The new layout should be
the first plot being 211, the second one being 212. How do I change
the first plot from 111 to 211? I haven't found a way other than re-add
the plots. Can some one shed some light on me please?
Thanks
Kun

Hi All,
I was downloading matplotlib on a windows machine and the sourceforge site 
(http://sourceforge.net/projects/matplotlib/) showed me basemap as the default 
download (instead of the latest matplotlib). On Mac the default download shows 
correctly as matplotlib.
This is some autodetection from sourceforge, so I don't know if it is a sitewide 
problem, or it can be configured from the project page. Just to let the admins know.
Best
-Kaushik