Rich Shepard wrote:
> On Fri, 1 Feb 2008, Eric Firing wrote:
>
>> What changed is that I added a warning where previously there was only a
>> silent error--the matplotlib.use command was being ignored. Sometimes
>> this (ignoring the command) is harmless, but it is never the user's intent
>> and in some cases it can cause puzzling problems. It often occurs when a
>> script or module does "from pylab import *" or "import pylab as P", and
>> then later "import matplotlib; matplotlib.use('Agg')". In this example,
>> the user intends to make plots non-interactively, writing them to files,
>> but the whole gui machinery for the default backend (e.g., gtkagg or wxagg
>> or tkagg) is imported unintentionally.
>
> Eric,
>
> Thanks for the explanation. And you bring up another issue that I have:
> the most appropriate way to generate non-interactive plots, written to
> files, for inclusion in a ReportLab report. Do I want to use pylab for this,
> plots embedded in wx, or something else?
If you are generating plots non-interactively--that is, entirely in a
script, so you don't need to see the plot on the screen to fiddle with
it--then use a non-interactive backend. WxAgg, TkAgg, GtkAgg, QtAgg,
etc. are needed only if you are working interactively. They don't
necessarily hurt otherwise, but they don't help.
I have taken a quick look at the ReportLab documentation, and it looks
like you are stuck with using PIL to import png files. (This means using
the Agg backend.) If what you are plotting is image-like, this is not so
bad, but it is not great in any case. It means things like text in your
plot (axes ticks, labels, etc.) that should be getting into your final
pdf in native form will instead get in as bit patterns, and this is bad
for both quality and file size. Same for lines; it would be much better
to generate vector graphics directly in your report. It would be nice
to have something like a pdf-to-reportlab or svg-to-reportlab code
generator, so you could use the pdf or svn matplotlib backend, and keep
vectors as vectors.
If your matplotlib plots can be on separate pages, then you could use
the pdf backend to generate those pages, and use pdftk to insert them
among the pages generated by ReportLab.
Whether to use pylab is an entirely separate issue; it is a matter of
programming style. The usual advice would be to use matplotlib.pyplot
for a very few functions (figure, close, maybe a few others) and then
use object-oriented style--that is, object method calls instead of
functions--for everything else. There is nothing wrong with sticking
with pylab or pyplot functions, though--they work fine.
>
> I need to get this module running properly so I am focusing on really
> understanding how to use matplotlib to produce what we need.
>
>> One way to find out where the warning is coming from is to invoke your
>> script
>> as
>>
>> python -Werror myscript.py
>>
>> which will turn the warning into an error and thereby trigger an exception
>> traceback.
>
> OK. Tomorrow morning I'll do this.
>
>> What this will *not* tell you is where the *earlier* call to
>> matplotlib.use() is occurring. To find it you will have to trace back
Note the following three lines carefully:
>> through your application, looking for the first place where pylab,
>> matplotlib.pyplot, or matplotlib.backends is imported, or the first
>> explicit use of matplotlib.use(), whichever is earliest.
Where and when matplotlib itself is imported doesn't matter--it is the
events listed above that are relevant to your question.
Eric
>
> There are two modules in which pylab is used: reports.py and functions.py.
> The former calls specific matplotlib functions in the latter.
>
> On the other hand, matplotlib is imported in several modules. Perhaps
> that's the problem. I'll check this tomorrow, too.
>
> Thanks,
>
> Rich
>
-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2008.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
_______________________________________________
Matplotlib-users mailing list
Matplotlib-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/matplotlib-users
