On 11/17/2010 03:41 PM, Kynn Jones wrote:
Hi. I am finding that matplotlib does not allow me to decouple
certain actions from the GUI as much as I'd like.
For example, I have not been able to do any of the following tasks.
Some of these tasks are certainly artificial, but they all succinctly
illustrate some of the problems I've been running into when doing more
realistic stuff.
1. /without bringing up any GUI window/,
Set the backend to a non-GUI backend, such as agg, pdf, ps, svg or cairo
by setting the 'backend' rcParam in matplotlibrc, or doing:
import matplotlib
matplotlib.use("Agg") # Must be the first call after importing matplotlib
generate a list of all the filetypes available to a specific
matplotlib installation for saving graphics (e.g. .ps, .svg, .pdf,
.png, etc.);
From a figure object:
figure.canvas.get_supported_filetypes()
returns a dictionary of supported file extensions, with mapping to more
detailed descriptions of each.
2. switch back-and-forth between sending graphics objects for display
to the GUI and sending them for saving to any of the available
filetypes (as defined in (1));
Once set to any of the GUI backends, you can use "show()" and
"savefig()" interchangeably.
3. (by far the most important one) /without activating any
backend/, create a graphics object (I explain what I mean by this below).
To clarify what I mean by (3), the best I can do is to give an example
from Mathematica. In Mathematica, a Graphics object does not need to
be displayed. It can be defined as a collection of Graphics
primitives, without ever displaying it in the GUI. One such
definition would be something like
In[1]:= g = Graphics[Line[{{1., 2.}, {2., 3.}, {3., 5.}}]];
This is what I mean in (3) by creating a graphics object without
displaying it (in the GUI). From a design perspective, this makes a
lot of sense, since a Graphics object, as an idea, is entirely
independent of whatever mean one chooses to display it. I want my
code to reflect this conceptual independence.
Regarding task (2), to make it more concrete, consider this (also
artificial) exercise: write a script that iterates over all filetypes
identified in (1); at each iteration, generate some random graphic
(e.g. of the sort shown here
http://matplotlib.sourceforge.net/examples/api/patch_collection.html),
display it on the GUI, and save it as a file of the type corresponding
to the iteration.
I would very much appreciate some hints/guidance on how to solve them.
As I noted, by far the most important of these tasks is (3). From
looking into the matplotlib source code, it looks to me impossible to
do this with standard matplotlib functions. But I am very much of a
noob with mpl, so I still hope there's a way.
In the worst case scenario (i.e. (3) can't be done directly using
standard mpl functions), then the only solution that I can think of
would involve implementing a separate layer of abstract graphics
objects, distinct from mpl's. This layer would then delegate to mpl
the task of displaying the graphics objects whenever the user requests
it. Any suggestions on how best to do this would be much appreciated.
In particular, I'd like to know what would be the right place to
insert this new graphics object layer into the matplotlib objects
stack. I think it would be best to make this connection at a level
deeper than the axes object, but I'm not quite sure how to do this.
I think you'll find matplotlib works exactly as you want. I think you
might find this part of the documentation useful:
http://matplotlib.sourceforge.net/faq/installing_faq.html#backends
Mike
Thanks in advance!
kj
------------------------------------------------------------------------------
Beautiful is writing same markup. Internet Explorer 9 supports
standards for HTML5, CSS3, SVG 1.1, ECMAScript5, and DOM L2& L3.
Spend less time writing and rewriting code and more time creating great
experiences on the web. Be a part of the beta today
http://p.sf.net/sfu/msIE9-sfdev2dev
_______________________________________________
Matplotlib-devel mailing list
Matplotlib-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
--
Michael Droettboom
Science Software Branch
Space Telescope Science Institute
Baltimore, Maryland, USA
------------------------------------------------------------------------------
Beautiful is writing same markup. Internet Explorer 9 supports
standards for HTML5, CSS3, SVG 1.1, ECMAScript5, and DOM L2 & L3.
Spend less time writing and rewriting code and more time creating great
experiences on the web. Be a part of the beta today
http://p.sf.net/sfu/msIE9-sfdev2dev
_______________________________________________
Matplotlib-devel mailing list
Matplotlib-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
