matplotlib-users Mailing List for matplotlib (Page 1397)

Steve Chaplin wrote:

>On Thu, 2004-11-18 at 18:14 -0500, Gary wrote:
>  
>
>>Returning after a time to my animation project.
>>
>>The first thing i did was to make sure anim_tk.py still runs.  It 
>>didn't.  A ghost figure window appears, and there is a long stall, then 
>>the message:
>>
>>elapsed 10.7956385487
>>Fatal Python error: PyEval_RestoreThread: NULL tstate
>>
>>This application has requested the Runtime to terminate it in an unusual 
>>way.
>>Please contact the application's support team for more information.
>>
>>Is it me, or did something break?
>>WinXP,  matplotlib 0.64, recently installed by deleting the existing 
>>matplolib directory and installing using the windows installer.  
>>Examples installed from the latest zip.
>>
>>thanks,
>>gary
>>    
>>
>Its working OK for me.
>Fedora 3 Linux, matplotlib 0.64, Python 2.3.4
>
>Steve
>
>  
>

Thanks ... so it's either me or WinXP.   I gave it a try on my other 
WinXP machine.   Same thing.  No dice.

Can someone confirm that anim_tk.py runs (or doesn't) on WinXP / 
matplotlib 0.64 ??

Thanks,
gary

>>>>> "Jochen" == Jochen Voss <vo...@se...> writes:


    Jochen> has vertical grid lines ONLY on the minor ticks, which
    Jochen> looks silly.  How do I get regularly spaced grid lines
    Jochen> here?

This is a consequence of the fact that the ticker skips minor ticks
which coincide with major ticks.  I am not sure this is the right
behavior, but was implemented to avoid other problems (overlapping
gridlines, for example, with anti-aliasing produces undesirable
results).  All you need to do is turn both major and minor grids on

    ax.xaxis.grid(True, which="minor")
    ax.xaxis.grid(True, which="major")

Should work....

JDH

Hello John,

thanks a lot for your help.  My picture is improving.
But one problem is left: the script

    from matplotlib.matlab import *
    from matplotlib.ticker import MultipleLocator

    subplot(211)
    ax=3Dgca()
    ax.xaxis.set_minor_locator(MultipleLocator(1))
    ax.xaxis.set_major_locator(MultipleLocator(5))
    ax.xaxis.grid(True, which=3D"minor")
    ax.yaxis.grid(False)
    semilogy([1,2,3,4,5,6,7,8,9,10,11],[1,2,3,4,5,6,7,8,9,10,11],basey=3D2)

    show()

has vertical grid lines ONLY on the minor ticks, which looks silly.
How do I get regularly spaced grid lines here?

All the best,
Jochen
--=20
http://seehuhn.de/

>>>>> "Jochen" == Jochen Voss <vo...@se...> writes:

    Jochen> Hello, I used matplotlib to create a graphical
    Jochen> representation of the boot process of my Debian GNU/Linux
    Jochen> system.  The result can be found at

    Jochen>     http://seehuhn.de/comp/bootlog.html

    Jochen> and especially in the (2400x1500 sized) picture

    Jochen>     http://seehuhn.de/comp/bootlog2.png

After looking again at your plot, particularly the rectangle parts
with text labels, it occurs to me that it would be nice to have a
general purpose class for this (rectangular boxes with text labels).
The class matplotlib.tables.Cell strives for this, but is not feature
complete.  What would be nice would be to be able to specify the
location of the text with respect to the box, with horizontal and
vertical alignment. This wouldn't be too hard, since text already has
these alignment flags with respect to an x,y location ( eg
http://matplotlib.sf.net/screenshots.html#align_text ).  

For full control, one would want to be able to specify the location of
x,y with respect to the rectangle (left, center, bottom, right, etc)
*and* the alignment of the text with respect to the x,y location, so
that one could have

--------------------
|                  |
|    centered      |
|                  |
--------------------

--------------------
|                  |
|                  | to-the-right
|                  |
--------------------


--------------------
|top-left-under    |
|                  | 
|                  |
--------------------


top-left-over
--------------------
|                  |
|                  | 
|                  |
--------------------

and so on.....  All the components are in place to make this
relatively easy from a layout persepctive.  One just has to plug them
together and make a nice, intuitive interface.  

JDH     

>>>>> "Jochen" == Jochen Voss <vo...@se...> writes:

    Jochen> Hello, I used matplotlib to create a graphical
    Jochen> representation of the boot process of my Debian GNU/Linux
    Jochen> system.  The result can be found at

    Jochen>     http://seehuhn.de/comp/bootlog.html

    Jochen> and especially in the (2400x1500 sized) picture

    Jochen>     http://seehuhn.de/comp/bootlog2.png

Very nice - you manage to pack a lot of information into the graph.
Edward Tufte would be proud!  It's nice to have folks stress testing
matplotlib

    Jochen> I have a question about matplotlib usage: 

  * I would like the picture to have vertical grid lines at positions
    1, 2, 3, 4, ..., On the horizontal x-Axis I would like to see
    labels at positions 0, 5, 10, 15, ...

The best way to do this would be to use minor ticks on 1,2,3,4,etc and
major ticks on 0,5,10,15 - the grids occur at the locations of the
ticks, and you can customize how you want the ticks labeled.  See
examples/major_minor_demo1.py and the use of the MultipleLocator.  The
Multiple locator places ticks at multiples of some base. For you minor
ticks you would use MultipleLocator(1) and for your major ticks
MultipleLocator(1).  The labels for the minor ticks are off by default
which is what you want, though you can customize this.

See http://matplotlib.sf.net/matplotlib.ticker.html for more info.

  * not horizonzal grid lines.  

The ax.xaxis.grid and ax.yaxis.grid functions can be used to
selectively turn on and off the grids for the respective axes.  The
signature is

    def grid(self, b, which='major'): 

where b is a boolean.  You can use this to control gridding for the
major and minor ticks on a per-axis basis.  So 

  ax.yaxis.grid(False) 



selectively turns off the grids for the y axis major tick grid lines.
The minor grids are off by default.  You can turn them on, eg with

   ax.xaxis.grid(True, which='minor') 

  * and I would like to get rid of the labels on the y-Axis.  Is this
    possible?

ax.set_yticklabels('')

See also the functions xticks and yticks in the matlab interface for
easy customization of tick locations and labels.

Cheers,
JDH

Hello,

I used matplotlib to create a graphical representation of the boot
process of my Debian GNU/Linux system.  The result can be found at

    http://seehuhn.de/comp/bootlog.html

and especially in the (2400x1500 sized) picture

    http://seehuhn.de/comp/bootlog2.png

I have a question about matplotlib usage: I would like the picture to
have vertical grid lines at positions 1, 2, 3, 4, ..., not horizonzal
grid lines.  On the horizontal x-Axis I would like to see labels at
positions 0, 5, 10, 15, ... and I would like to get rid of the labels
on the y-Axis.  Is this possible?  How do I do it?

All the best,
Jochen
--=20
http://seehuhn.de/

On Thu, 2004-11-18 at 18:14 -0500, Gary wrote:
> Returning after a time to my animation project.
> 
> The first thing i did was to make sure anim_tk.py still runs.  It 
> didn't.  A ghost figure window appears, and there is a long stall, then 
> the message:
> 
> elapsed 10.7956385487
> Fatal Python error: PyEval_RestoreThread: NULL tstate
> 
> This application has requested the Runtime to terminate it in an unusual 
> way.
> Please contact the application's support team for more information.
> 
> Is it me, or did something break?
> WinXP,  matplotlib 0.64, recently installed by deleting the existing 
> matplolib directory and installing using the windows installer.  
> Examples installed from the latest zip.
> 
> thanks,
> gary
Its working OK for me.
Fedora 3 Linux, matplotlib 0.64, Python 2.3.4

Steve

Returning after a time to my animation project.

The first thing i did was to make sure anim_tk.py still runs.  It 
didn't.  A ghost figure window appears, and there is a long stall, then 
the message:

elapsed 10.7956385487
Fatal Python error: PyEval_RestoreThread: NULL tstate

This application has requested the Runtime to terminate it in an unusual 
way.
Please contact the application's support team for more information.

Is it me, or did something break?
WinXP,  matplotlib 0.64, recently installed by deleting the existing 
matplolib directory and installing using the windows installer.  
Examples installed from the latest zip.

thanks,
gary

On Tue, 2004-11-16 at 17:45 +1100, matthew arnison wrote:
> Oh dear. I'm going to take another u-turn, and say I hit this
> IMAGE_FORMAT attribute glitch again.
> 
> To atone for my reversals, I have isolated a test case, and I attach
> sample code. It seems to be triggered by importing matplotlib.matlab in
> one module, and importing matplotlib backend stuff directly in another
> module.
> 
> Running frog.py gives:
> 
> Traceback (most recent call last):
...
> "C:\Python23\lib\site-packages\matplotlib\backends\backend_gtk.py", line
> 1423, in __init__
>       self.IMAGE_FORMAT         =
> matplotlib.backends.backend_mod.IMAGE_FORMAT
> AttributeError: 'module' object has no attribute 'IMAGE_FORMAT'

Its now fixed in CVS. backend_gtk now knows about all image formats and
does not need to look at other backends to see what formats they
support.

Steve

jk...@ik... wrote:
> Arguably Matlab has the elegant Lisp-like feature lacking in Python of
> multiple return values. In Lisp you can write
> 
>   (setq x (floor 3.14))
> 
> to set the value of x to 3, or
> 
>   (multiple-value-setq (x y) (floor 3.14))
> 
> to set the value of x to 3 and the value of y to 0.14. Note how it is
> left up to the caller of the FLOOR function whether to capture just
> the first returned value or both of them. This is paralleled by
> Matlab's
> 
>   x = some_function(a,b,c)
>   [x,y] = some_function(a,b,c)
> 
> where the caller decides how many values will be returned.

Note that you can simply "emulate" this missing Python feature by 
appending indexes after your function call:

	x = some_function(a,b,c)[0]
	x, y = some_function(a,b,c)[:2]
	and so on...

Naturally this does not save computation as nargout could do, but is 
this really an issue? IMHO this is generally not.

JM. Philippe

Hello!

The problem was a problem with pygtk 2.4.0 and was caused by a parameter 
name "typename" which for C++ is also a keyword.  Any C++ application 
using pygtk was affected and agg (which matplotlib is using) is written 
in C++.  The fix to this problem was (among other few changes) to rename 
"typename" to "_typename", which was done in CVS shortly after pygtk 
2.4.0 was released.

In conclusion, just download pygtk 2.4.1 from pygtk.org and it will work!

Niklas Volbers.




Rich Drewes wrote:
> Hello,
> 
> Several users (including Humufr and Niklas Volbers) have reported on this
> list a compile error building matplotlib with pygtk.  The error looks
> something like this:
> 
> In file included from src/_gtkagg.cpp:8:
>  /usr/include/pygtk-2.0/pygobject.h:124: error: parse error before 
> `typename"
>  /usr/include/pygtk-2.0/pygobject.h:131: error: parse error before 
> `typename"
> 
> I also experienced this problem.  It appears to be some sort of namespace
> collision on the token "typename" (what this is colliding with isn't
> clear).  By changing "typename" to "typname" or some other spelling in
> /usr/include/pygtk-2.0/pygobject.h I was then able to build matplotlib
> successfully.
> 
> If someone knows what is causing this and has a better solution, please
> advise.  Perhaps it has something to do with GCC 3.4.x and that particular
> pygtk release.
> 
> Rich Drewes
> 
> 
> -------------------------------------------------------
> This SF.Net email is sponsored by: InterSystems CACHE
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> 

>>>>> "Rich" == Rich Drewes <dr...@in...> writes:

    Rich> Hello, Several users (including Humufr and Niklas Volbers)
    Rich> have reported on this list a compile error building
    Rich> matplotlib with pygtk.  The error looks something like this:

    Rich> In file included from src/_gtkagg.cpp:8:
    Rich> /usr/include/pygtk-2.0/pygobject.h:124: error: parse error
    Rich> before `typename" /usr/include/pygtk-2.0/pygobject.h:131:
    Rich> error: parse error before `typename"

    Rich> I also experienced this problem.  It appears to be some sort
    Rich> of namespace collision on the token "typename" (what this is
    Rich> colliding with isn't clear).  By changing "typename" to
    Rich> "typname" or some other spelling in
    Rich> /usr/include/pygtk-2.0/pygobject.h I was then able to build
    Rich> matplotlib successfully.

Don't do that!  That looks brtually hackish.

See http://matplotlib.sourceforge.net/faq.html#PYGTK24

First off, thanks to everyone for the replies.

I think the problem turned out to be that when you do a `python setup.py
clean` it does not clean out the build directory (despite what it is
saying).  I manually cleaned it out, rebuilt and everything is fine.   There
must have been some strangeness left over from when I was trying to resolve
my include_dir issues I mentioned before. 

Just for the record, I am having no problems building against numarray 1.1
or 1.1.1.  I started to try to use numeric, but it wanted a lib for cblas
that I didn't have.  Before I started any of this, I deleted all old
versions of numarray and matplotlib is had in site-packages.

Thanks again for the help,
Scott.



-----Original Message-----
From: John Hunter [mailto:jdh...@ni...]
Sent: Wednesday, November 17, 2004 4:57 PM
To: Zelakiewicz, Scott (Research)
Cc: 'mat...@li...'
Subject: Re: [Matplotlib-users] Simple plot command fails


>>>>> "Zelakiewicz," == Zelakiewicz, Scott (Research) <zel...@cr...>
writes:

   Scott> Still no luck.  I am not trying to run this
   Scott> interactively.  Switching between TkAgg and GTKAgg
   Scott> does not seem to do anything.

Did you try rm -rf your old site-packages/matplotlib and your build
subdirectory of the matplotlib src tree, and rebuild/install
matplotlib cleanly?

If that fails, it might be instructive to edit
"/local/lib/python2.2/site-packages/matplotlib/lines.py", line 234,
and print len(x), len(y) and seeing what the hell is going on, since
the last error is

    if midPoint and self.gridOn:  self.gridline.draw(renderer)
  File "/local/lib/python2.2/site-packages/matplotlib/lines.py", line 234,
in draw
    xt, yt = self._transform.numerix_x_y(x, y)
ValueError: x and y must be equal length sequences

Finally, I can see that this is an error arising from drawing the
grid.  Does it go away if you turn the grid off (axes.grid : False in
rc and comment out the grid call in simple_plot).  

I'm grasping at straws here - my best guess is above, that you have
some incompatible old matplotlib lying around.

JDH

>>>>> "Zelakiewicz," == Zelakiewicz, Scott (Research) <zel...@cr...> writes:

   Scott> Still no luck.  I am not trying to run this
   Scott> interactively.  Switching between TkAgg and GTKAgg
   Scott> does not seem to do anything.

Did you try rm -rf your old site-packages/matplotlib and your build
subdirectory of the matplotlib src tree, and rebuild/install
matplotlib cleanly?

If that fails, it might be instructive to edit
"/local/lib/python2.2/site-packages/matplotlib/lines.py", line 234,
and print len(x), len(y) and seeing what the hell is going on, since
the last error is

    if midPoint and self.gridOn:  self.gridline.draw(renderer)
  File "/local/lib/python2.2/site-packages/matplotlib/lines.py", line 234,
in draw
    xt, yt = self._transform.numerix_x_y(x, y)
ValueError: x and y must be equal length sequences

Finally, I can see that this is an error arising from drawing the
grid.  Does it go away if you turn the grid off (axes.grid : False in
rc and comment out the grid call in simple_plot).  

I'm grasping at straws here - my best guess is above, that you have
some incompatible old matplotlib lying around.

JDH

Still no luck.  I am not trying to run this interactively.  Switching
between TkAgg and GTKAgg does not seem to do anything.

Here is the output from  `python simple_plot.py --verbose-helpful`

Thanks again,
Scott.




zelakiew@shake> python simple_plot.py --verbose-helpful
matplotlib data path /local/share/matplotlib
loaded rc file /home/zelakiew/.matplotlibrc
matplotlib version 0.64
verbose.level helpful
interactive is 0
numerix numarray 1.1.1
font search path ['/local/share/matplotlib']
loaded ttfcache file /home/zelakiew/.ttffont.cache
matplotlib data path /local/share/matplotlib
loaded rc file /home/zelakiew/.matplotlibrc
matplotlib version 0.64
verbose.level helpful
interactive is 0
backend TkAgg version 8.3
Traceback (most recent call last):
  File "simple_plot.py", line 17, in ?
    show()
  File
"/local/lib/python2.2/site-packages/matplotlib/backends/backend_tkagg.py",
line 68, in show
    manager.show()
  File
"/local/lib/python2.2/site-packages/matplotlib/backends/backend_tkagg.py",
line 284, in show
    self.canvas.draw()
  File
"/local/lib/python2.2/site-packages/matplotlib/backends/backend_tkagg.py",
line 135, in draw
    FigureCanvasAgg.draw(self)
  File
"/local/lib/python2.2/site-packages/matplotlib/backends/backend_agg.py",
line 310, in draw
    self.figure.draw(self.renderer)
  File "/local/lib/python2.2/site-packages/matplotlib/figure.py", line 254,
in draw
    for a in self.axes: a.draw(renderer)
  File "/local/lib/python2.2/site-packages/matplotlib/axes.py", line 963, in
draw
    self.xaxis.draw(renderer)
  File "/local/lib/python2.2/site-packages/matplotlib/axis.py", line 478, in
draw
    tick.draw(renderer)
  File "/local/lib/python2.2/site-packages/matplotlib/axis.py", line 131, in
draw
    if midPoint and self.gridOn:  self.gridline.draw(renderer)
  File "/local/lib/python2.2/site-packages/matplotlib/lines.py", line 234,
in draw
    xt, yt = self._transform.numerix_x_y(x, y)
ValueError: x and y must be equal length sequences




-----Original Message-----
From: John Hunter [mailto:jdh...@ni...]
Sent: Wednesday, November 17, 2004 4:21 PM
To: Zelakiewicz, Scott (Research)
Cc: 'Stephen Walton'; 'mat...@li...'
Subject: Re: [Matplotlib-users] Simple plot command fails

To test your installation, cd into the examples dir and try running
simple_plot.py from the unix shell.

  > cd examples
  > python simple_plot.py

  OR you can choose your backend from the shell with

  > python simple_plot.py -dTkAgg    
  > python simple_plot.py -dGTKAgg

If that works, almost surely you have an interactive problem that will
be cleared up with the links above.  If now, rerun the script with
--verbose-helpful and report back.

Good luck,
JDH

>>>>> "Zelakiewicz," == Zelakiewicz, Scott (Research) <zel...@cr...> writes:

  Scott> Sorry, I should have explicitly stated most of this:
  Scott> This is on Redhat 9.0.  I built numarray and
  Scott> matplotlib myself.

  Scott> Initially the matplotlib build had problems finding
  Scott> the numarray headers since I have to install
  Scott> everything to a non-standard place (I don't have
  Scott> root) and simply modifying basedir in setupext.py
  Scott> did not work.  I made some sym-links and added to an
  Scott> include_dir to fix that and now there are no build
  Scott> problems.

  Scott> My .matplotlibrc is identical to the one put in
  Scott> share/matplotlib except numerix is set to 'numarray'
  Scott> and set datapath to '/local/share/matplotlib' which
  Scott> is where all the fonts and stuff are.

If you are running interactively from the python shell, you need to
make sure "interactive" is set to True in your rc file and do not use
show.  

  http://matplotlib.sourceforge.net/faq.html#SHOW


Also, to work interactively, you must use either the tkagg backend or
a python shell that supports threading for the GUI you are using (GTK
or WX) such as ipython http://ipython.scipy.org, which has explicit
support for matplotlib in the pylab mode

  http://matplotlib.sourceforge.net/interactive.html

To test your installation, cd into the examples dir and try running
simple_plot.py from the unix shell.

  > cd examples
  > python simple_plot.py

  OR you can choose your backend from the shell with

  > python simple_plot.py -dTkAgg    
  > python simple_plot.py -dGTKAgg

If that works, almost surely you have an interactive problem that will
be cleared up with the links above.  If now, rerun the script with
--verbose-helpful and report back.

Good luck,
JDH

On Wed, 2004-11-17 at 13:15 -0500, Zelakiewicz, Scott (Research) wrote:

> This is on Redhat 9.0.  I built numarray and matplotlib myself.  
> 
> Initially the matplotlib build had problems finding the numarray headers
> since I have to install everything to a non-standard place (I don't have
> root)

Oof.  I'm afraid I can't be much help.  I long ago updated all my RH9
boxes to FC1 and I also have root access on them.  Can anyone else
reproduce these problems?

-- 
Stephen Walton, Professor of Physics and Astronomy,
California State University, Northridge
ste...@cs...

Sorry, I should have explicitly stated most of this:

This is on Redhat 9.0.  I built numarray and matplotlib myself.  

Initially the matplotlib build had problems finding the numarray headers
since I have to install everything to a non-standard place (I don't have
root) and simply modifying basedir in setupext.py did not work.  I made some
sym-links and added to an include_dir to fix that and now there are no build
problems. 

My .matplotlibrc is identical to the one put in share/matplotlib except
numerix is set to 'numarray' and set datapath to '/local/share/matplotlib'
which is where all the fonts and stuff are.

Thanks again,
Scott.



-----Original Message-----
From: Stephen Walton [mailto:ste...@cs...]
Sent: Wednesday, November 17, 2004 12:55 PM
To: Zelakiewicz, Scott (Research)
Cc: 'mat...@li...'
Subject: Re: [Matplotlib-users] Simple plot command fails


On Wed, 2004-11-17 at 12:44 -0500, Zelakiewicz, Scott (Research) wrote:

> Any help/suggestions would be appreciated.

What OS version/distribution are you running?  Did you built matplotlib
yourself?  Any errors in the build?  What is in your $HOME/.matplotlibrc
file?

-- 
Stephen Walton, Professor of Physics and Astronomy,
California State University, Northridge
ste...@cs...

On Wed, 2004-11-17 at 12:44 -0500, Zelakiewicz, Scott (Research) wrote:

> Any help/suggestions would be appreciated.

What OS version/distribution are you running?  Did you built matplotlib
yourself?  Any errors in the build?  What is in your $HOME/.matplotlibrc
file?

-- 
Stephen Walton, Professor of Physics and Astronomy,
California State University, Northridge
ste...@cs...

Hi,

I am trying to get matplotlib (0.64) up and running.   When I run the
following commands
	from matplotlib.matlab import *
	figure(1)
	plot([1,2,3,4])
	show()
I get an error message (shown below), the figure window draws with the
buttons on the bottom, but no plot is drawn.  I have tried this with the
GTKAgg and TkAgg backends and they both give the same error.  If it matters,
I am using numarray.

Any help/suggestions would be appreciated.

Thanks,
Scott.



Python 2.2.2 (#1, Feb 24 2003, 19:13:11)
[GCC 3.2.2 20030222 (Red Hat Linux 3.2.2-4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from matplotlib.matlab import *
>>> figure(1)
<matplotlib.figure.Figure instance at 0x86cea2c>
>>> plot([1,2,3,4])
[<matplotlib.lines.Line2D instance at 0x87470cc>]
>>> show()
/local/usr/src/garnome2.6.2/lib/python2.2/site-packages/gtk-2.0/gtk/__init__
.py: 83: GtkDeprecationWarning: gtk.mainloop is deprecated, use gtk.main
instead
  self.warn(message, DeprecationWarning)
Traceback (most recent call last):
  File
"/local/lib/python2.2/site-packages/matplotlib/backends/backend_gtkagg.py ",
line 96, in callback
    else: self.draw()
  File
"/local/lib/python2.2/site-packages/matplotlib/backends/backend_gtkagg.py ",
line 44, in draw
    FigureCanvasAgg.draw(self)
  File
"/local/lib/python2.2/site-packages/matplotlib/backends/backend_agg.py",
line 310, in draw
    self.figure.draw(self.renderer)
  File "/local/lib/python2.2/site-packages/matplotlib/figure.py", line 254,
in d raw
    for a in self.axes: a.draw(renderer)
  File "/local/lib/python2.2/site-packages/matplotlib/axes.py", line 963, in
dra w
    self.xaxis.draw(renderer)
  File "/local/lib/python2.2/site-packages/matplotlib/axis.py", line 478, in
dra w
    tick.draw(renderer)
  File "/local/lib/python2.2/site-packages/matplotlib/axis.py", line 132, in
dra w
    if midPoint and self.tick1On: self.tick1line.draw(renderer)
  File "/local/lib/python2.2/site-packages/matplotlib/lines.py", line 234,
in dr aw
    xt, yt = self._transform.numerix_x_y(x, y)
ValueError: x and y must be equal length sequences
 

>>>>> "Norbert" == Norbert Nemec <Nor...@gm...> writes:

    Norbert> I just sent patches about this to matplotlib-devel.  The
    Norbert> current version has two problems with this:

Until these are incorporated, there is still an easy way to customize
the legend text (and other properties of legends) which is illustrated
in http://matplotlib.sf.net/examples/legend_demo.py.  Here is the
approach, in brief

    leg = legend(... legend args here)
    texts = leg.get_texts()
    set(texts, fontsize='small', color='r')

JDH

[Apologies if this message is a duplicate; it seems that Gmane ate my
previous attempt at replying, since I sent another message to the list
before acking Gmane's autoreply.]

Andrew Straw writes:

> To me, nargout, like so much of Matlab, is a brutish hack introduced
> because that language is not as capable or elegant as Python. 

Arguably Matlab has the elegant Lisp-like feature lacking in Python of
multiple return values. In Lisp you can write

  (setq x (floor 3.14))

to set the value of x to 3, or

  (multiple-value-setq (x y) (floor 3.14))

to set the value of x to 3 and the value of y to 0.14. Note how it is
left up to the caller of the FLOOR function whether to capture just
the first returned value or both of them. This is paralleled by
Matlab's

  x = some_function(a,b,c)
  [x,y] = some_function(a,b,c)

where the caller decides how many values will be returned.

I imagine nargout could have arisen as an optimization aid: if a value
is not needed, the function can decide to not compute it. A reasonably
good Lisp compiler would probably do this optimization automatically,
but Matlab is (or was, until some recent version?) an interpreted
language with fewer opportunities for optimization.

Where Matlab goes terribly wrong (IMHO) is in that it encourages abuse
of the nargout mechanism: built-in functions like find change their
behavior depending on how many return values are expected. In effect,
the name "find" denotes two different functions, dispatched by the
value of nargouts.

> Regardless of whether your sense of aesthetics is different than mine,
> the kind of low-level shenanigans suggested as a work-around seems, at
> the very least, brittle and prone to maintenance and portability
> issues.  (Would that even work on IronPython or PyPy?)

I imagine that the Psyco JIT compiler might have some problems with
the hack.

I would like to amend my suggestion upthread: instead of changing
mlab.find, add another function, say find2 unless someone thinks of a
better name, that always returns a tuple. The current version of find
could be left as it is, or, even better (this might be important for
automatic Matlab-to-Python translation), changed to return a single
index for any kind of array. This would require a mechanism for
addressing array elements by a single index, which probably doesn't
exist. For Matlab compatibility, the addressing should use the
column-major, i.e., Fortran, order.

In fact, I don't see why this wouldn't solve the problem of automatic
translation of functions that use nargout. The value of nargout is a
static feature of the function call, so the translator should easily
be able to dispatch according to the value, or add it as a keyword
argument. That is, if the user has a function like

  function [a,b]=foo(bar)
  switch nargout,
    case 1, a=bar;
    case 2, a=1; b=bar;
  end

the translator could produce the Python function

  def foo(bar, nargout=0):
      if nargout==1:
          return bar;
      elif nargout==2:
          return (1,bar);

and translate

  foo(1);
  a=foo(2);
  [b,c]=foo(3);

to

  foo(1);
  a=foo(2,nargout=1);
  (b,c)=foo(3,nargout=2);

I wouldn't do this for find, since (in my experience) the
two-return-value form of find is the more common case, and it would
not be very nice to always type in the nargout parameter when using
matplotlib interactively.

> it seems to me that early design mistakes resulted in terrible
> backwards compatibility issues, as well.  For example, I remember
> being driven mad trying to figure out whether parentheses were
> needed when calling certain functions.  I guess for some they are
> required and for others they aren't.

I wonder if this is the same problem that I had for a long time: I
finally realized that Matlab either does both auto-parenthesizing and
auto-quoting, or neither of them, so

  print -depsc2 fname

is equivalent to

  print('-depsc2', 'fname')

so if you want to create one of the parameters dynamically, you cannot
use the first form but will have to write something like

  print('-depsc2', sprintf('picture-%d', num))

(Then there is the confusion of {} vs () indexing, and cell strings
that are almost like real strings but sometimes need a {:} after them,
except that if you get them from a function, since the parser gets
confused if you type fun(param){:} so you need a temp variable, and
cell arrays of structs that sometimes act like structs of cell
arrays... Automatic translation of Matlab code will certainly have
some interesting challenges.)

-- 
Jouni K Seppänen

I just sent patches about this to matplotlib-devel.

The current version has two problems with this:

* legend does not take kwargs. All the options like FONTSIZE, PAD and others 
can only be set globally as class variables of Legend

* the option FONTSIZE - even if changed globally - is flat out ignored. It is 
used once for a calculation, but the crucial routine Legend.draw() completely 
ignores it.

Both problems are fixed with my patches (see matplotlib-devel or wait for them 
to appear in CVS)

Ciao,
Norbert


On Tuesday 16 November 2004 18:52, Cory Davis wrote:
> Hi All,
>
> Can anyone tell me how to change the size of the legend produced by
> matlab.legend independently of my axis tick labels?
>
> lh=legend(['a','b','c'],loc=4,fontsize=8)
>
> doesn't work and there seems to be nothing in the lh object that would
> help.
>
> Cheers,
> Cory
>
>
>
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-- 
_________________________________________Norbert Nemec
         Bernhardstr. 2 ... D-93053 Regensburg
     Tel: 0941 - 2009638 ... Mobil: 0179 - 7475199
           eMail: <No...@Ne...>

Hi,

One thing that I really like about Matlab's handle graphics system is
that it is self-documenting: if I do h=plot(...), I can query the
current values of all properties with get:

  >> get(h)
          Color = [0 0 1]
          EraseMode = normal
          LineStyle = -
          LineWidth = [0.5]
[...]   
          UserData = []
          Visible = on

Also, if I'm interested in changing something but don't know the
allowed values, I can use set:

  >> set(h,'linestyle')
  [ {-} | -- | : | -. | none ]
  >> set(h,'erasemode')
  [ {normal} | background | xor | none ]
  >> set(h,'markersize')
  A line's "MarkerSize" property does not have a fixed set of property values.

I'm attaching a patch that adds something like this to Matplotlib. For
get, the changes are quite straightforward, but for set, the correct
design is not obvious. I have added some example documentation to axes
objects, so set(gca()) returns something useful.

But, again, I'm not sure about the design, so please consider this
patch not as something I'd like applied to matplotlib right now, but
as a suggestion of a feature I would like to see added.

-- 
Jouni K Seppänen

On Nov 16, 2004, at 4:51 PM, Darren Dale wrote:
> Maybe my example wasn't clear. There are good reasons for using 
> varargout and nargout in Matlab. If I write a function to fit a peak, 
> I can return the position, height, FWHM and sumResiduals along with 
> some information about how the peakfitting algorithm concluded. If a 
> user calls [p,h,fwhm,sr] = peakfit(x,y), you use nargout to determine 
> that the caller does not want the algorithm report.

Hi Darren,

I sometimes return a dict in cases like this:

fit = peakfit(x,y)
print fit['position']
print fit['height']
print fit['FWHM']

and so on...

Sometimes, the results I always want get returned on their own and 
optionally return all results:

p,h            = peakfit(x,y)                  # return just the basic 
results
p,h,fit_extras = peakfit(x,y,full_output=True) # return everything
print fit_extras['FHWM']

(I think some scipy functions operate more-or-less like this, too. 
Perhaps without returning results in a dict, but merely as extra 
arguments.)

I have to agree with the opinions of Chris Barker and John Hunter 
cautioning against writing new code using an 'nargout-alike'.  (When 
translating Matlab code to Python I can see that it might be useful.) 
Furthermore, I often find myself grabbing the results of a function 
call in one variable, stuffing it somewhere, and later, knowing it's a 
tuple, examining the elements later. This handy trick would be 
impossible with an nargout-based implementation.

To me, nargout, like so much of Matlab, is a brutish hack introduced 
because that language is not as capable or elegant as Python.  (To 
digress further and probably show the era at which I left Matlab to be 
around 5.x, it seems to me that early design mistakes resulted in 
terrible backwards compatibility issues, as well.  For example, I 
remember being driven mad trying to figure out whether parentheses were 
needed when calling certain functions.  I guess for some they are 
required and for others they aren't.  I think it would be very 
difficult to define the syntax for Matlab as done in the Python 
(Language) Reference Manual. And let's not get into issues of object 
oriented programming, types and 'everything is a (double precision) 
matrix'.)

Regardless of whether your sense of aesthetics is different than mine, 
the kind of low-level shenanigans suggested as a work-around seems, at 
the very least, brittle and prone to maintenance and portability 
issues.  (Would that even work on IronPython or PyPy?)

Anyhow, if you're not scared by bytecode hacks in your initial 
toe-dipping forays into Python, I invite you to dive in!

Cheers!
Andrew