matplotlib-users Mailing List for matplotlib

On Fri, 08 Oct 2004, John Hunter apparently wrote:
> Could you send some example code when axis is used first with a
> description of what looks wrong to you on the plot?

from scipy import *
from matplotlib.matlab import *
days=arange(31)                 
dp = 3                         
plot(days,dp*days,'ro')
#produce a zero axis
axis([0,30,-40,100])
axhline(linewidth=0.5,color=(0,0,0))
show()

Version is 0.63.
Ordered as above: axis is not honored.
Switch the order of axis() and axhline(),
and all is well.

Hope that's clear.

Cheers,
Alan

>>>>> "Alan" == Alan G Isaac <ai...@am...> writes:

    Alan> Unless I send this when I notice it, I'll forget to send it.
    Alan> But I'm not so cold hearted as to hope for any response from
    Alan> John during the early weeks of fatherhood!

No worries - these babies sleep like mad.  I get a few minutes a day
to catch up.

    Alan> If a plot makes use of both axhline() and axis(), then
    Alan> axis() must come last or the results are not as expected.
    Alan> Actually I have found it often desirable for axis to come
    Alan> last, but I will simply raise the question of whether this
    Alan> need---possibly surprising to a new user---might be
    Alan> transcended.

Could you send some example code when axis is used first with a
description of what looks wrong to you on the plot?

JDH

On Fri, 8 Oct 2004, John Hunter wrote:

> >>>>> "Yann" == Yann Le Du <yan...@no...> writes:
> 
>     Yann> Hello again, I found the solution : in file transforms.py I
>     Yann> changed the lines 181-183 by replacing :
> 
>     Yann> from _transforms import ...
> 
> It looks like your matplotlib directory is out of whack.  You should
> remove the entire build tree and start over.  In matplotlib-0.63,
> _transforms.so does not exist; it is replaced by
> _lib/matplotlib/_transforms.py, which imports either the _na or _nc
> version.
> 
> So even though you got it to work, that you had a problem at all
> indicates your src directory is messed up, and so I advise you to get
> a clean start.

Yes indeed, I've removed my site-packages/matplotlib directory and
reinstalled, and it works fine ! I found it strange to be the only one
with that problem, but in fact it's just because others keep things tidier
than I do...

Thanks,

-- 
Yann Le Du

http://www-thphys.physics.ox.ac.uk/users/YannLeDu

>>>>> "Jean-Michel" == Jean-Michel Philippe <jea...@ir...> writes:

    Jean-Michel> Ok. Now suppose you write an application that runs a
    Jean-Michel> set of algorithms not known in advance. These
    Jean-Michel> algorithms may or may not create figures depending on
    Jean-Michel> what they perform; they may also encounter
    Jean-Michel> difficulties (e.g. not enough input data) so that
    Jean-Michel> none of them is finally able to create a figure. As
    Jean-Michel> this is always better to dissociate code pieces the
    Jean-Michel> more as possible, I'd prefer not to use a global
    Jean-Michel> variable to trace figure creation. So is there a way
    Jean-Michel> to know that no figure was created?

In 0.63, we introduced a flag on the
matplotlib.backends.draw_if_interactive function.  If
draw_if_interactive._called is False, the function was never called
and thus no plotting commands were issued.  You may be able to use
this to decide whether to call show or not.  

Eg , at the end of your script

  if draw_if_interactive._called: show()

Note if you are using a pure image backend (eg agg, svg, ps) you do
not need show at all; this is for GUI backends only.  Just call
savefig anywhere in your code.

But if you really want full control with no magic globals, I suggest
using the matplotlib API rather than the matlab interface.  Here is a
minimal example with the SVG backend to create a figure w/o the matlab
interface

  
  from matplotlib.backends.backend_svg import FigureCanvasSVG
  from matplotlib.figure import Figure
  fig = Figure()
  ax = fig.add_subplot(111)
  ax.plot([1,2,3])
  canvas = FigureCanvasSVG(fig)
  canvas.print_figure('myfile.svg')

There are several examples called embedding_in_*.py at
http://matplotlib.sf.net/examples that show how to do this for your
GUI of choice.

Let me know if you need more help; and be sure to tell which backend
you are targetting.

JDH

>>>>> "Stephen" == Stephen Walton <ste...@cs...> writes:

    Stephen> On Tue, 2004-10-05 at 09:30, Wasinee Rungsarityotin
    Stephen> wrote:
    >> src/_na_image.cpp:780: `png_infopp_NULL' undeclared (first use
    >> this function)

    Stephen> On my system this is defined in /usr/include/png.h, part
    Stephen> of libpng version 1.2.5.  -- Stephen Walton
    Stephen> <ste...@cs...> Dept. of Physics & Astronomy,
    Stephen> Cal State Northridge

I second this - it looks like it may be a libpng version problem.  Off
the top of my head, I don't know what the minimum libpng version
requirement is, but if 1.2.5 is working for Stephen, I suggest
installing that or later.

JDH

>>>>> "Yann" == Yann Le Du <yan...@no...> writes:

    Yann> Hello again, I found the solution : in file transforms.py I
    Yann> changed the lines 181-183 by replacing :

    Yann> from _transforms import ...

It looks like your matplotlib directory is out of whack.  You should
remove the entire build tree and start over.  In matplotlib-0.63,
_transforms.so does not exist; it is replaced by
_lib/matplotlib/_transforms.py, which imports either the _na or _nc
version.

So even though you got it to work, that you had a problem at all
indicates your src directory is messed up, and so I advise you to get
a clean start.

JDH