Re: [Matplotlib-users] using plotting contexts

[John H. <jdh...@ac...>]

>>>>> "Perry" == Perry Greenfield <pe...@st...> writes:

    Perry> Is there a means of using alternate rcParams dictionaries
    Perry> for use with different backends, say as a parameter to the
    Perry> print_figure method? It doesn't look like it at the
    Perry> moment. I'd guess to do that now means replacing rcParams
    Perry> temporarily, rendering the plot to the file, and resetting
    Perry> rcParams to what it was (I haven't actually tried it), but
    Perry> that seems clumsier than it should be.

There are a few ways to go here.

Probably the best is based on the answer to "How do I customize the
default behavior of a single figure?"
http://matplotlib.sourceforge.net/faq.html#CUSTOM

Ie, you can set the rc params for a given session by updating the rc
dict before importing matplotlib.  You could set up a module like
plot_contexts 

plot_contexts.py::

from matplotlib import rcParams

def use(s):
    if s == 'powerpoint':
        rcParams['figure.facecolor']   = 'b'
        rcParams['text.fontname']   = 'cmr10'
        rcParams['lines.linewidth'] = 2.0
    elif s = 'some journal'
        and so on


And at the script level you could do

import plot_contexts
plot_contexts.use('powerpoint')
from matplotlib.matlab import *

The one down side of the rcParams approach is that currently all the
object defaults are evaluated at module load time, so you can only
switch at the start of your python session.  Eg, the current
constructors look like

class Line2D(Artist):
    def __init__(self, xdata, ydata,
                 linewidth=rcParams['lines.linewidth'],
                 linestyle=rcParams['lines.linestyle'],
                 )

By changing all the constructor defaults to 

    def __init__(self, xdata, ydata,
                 linewidth=None,
                 linestyle=None,
                 ):
                 if linewidth is None: linewidth = rcParams['lines.linewidth'],
                 if linestyle is None: linestyle = rcParams['lines.linestyle'],

we could defer those evaluations to construction time, so you could
switch contexts in the middle of an interactive session

  >>> plot_contexts.use('power point')
  >>> make_some_figs()
  >>> plot_contexts.use('some journal')
  >>> make_some_figs()  # again

I already did this for the FontProperties so you can have context
fonts, as in examples/font_properties_demo.py.  It wouldn't be much
work to do the same for the other properties controlled by rc.

As another approach, I have considered making the matplotlibrc finder
check the current dir first, and using that file if it finds one.
Then you could have dir based contexts.

JDH