Merge pull request matplotlib#861 from memmett/master

Add rcfile function (which loads rc params from a given file) and associated context manager.

Author: pelson

doc/users/whats_new.rst

@@ -89,6 +89,21 @@ interval.
 .. plot:: examples/pylab_examples/boxplot_demo3.py
 
 
+New RC parameter functionality
+------------------------------
+
+Matthew Emmett added a function and a context manager to help manage
+RC parameters: :func:`~matplotlib.rc_file` and
+:class:`~matplotlib.rc_context`.  To load RC paramters from a file::
+
+  >>> mpl.rc_file('mpl.rc')
+
+To temporarily use RC parameters::
+
+  >>> with mpl.rc_context(fname='mpl.rc', rc={'text.usetex': True}):
+  >>>     ...
+
+
 .. _whats-new-1-1:
 
 new in matplotlib-1.1

lib/matplotlib/__init__.py

@@ -178,7 +178,6 @@ def byte2str(b): return b
             __version__numpy__, numpy.__version__))
 del version
 
-
 def is_string_like(obj):
     if hasattr(obj, 'shape'): return 0
     try: obj + ''
@@ -716,6 +715,12 @@ def rc_params(fail_on_error=False):
         warnings.warn(message)
         return ret
 
+    return rc_params_from_file(fname, fail_on_error)
+
+
+def rc_params_from_file(fname, fail_on_error=False):
+    """Load and return params from fname."""
+
     cnt = 0
     rc_temp = {}
     with open(fname) as fd:
@@ -898,6 +903,52 @@ def rcdefaults():
     """
     rcParams.update(rcParamsDefault)
 
+
+def rc_file(fname):
+    """
+    Update rc params from file.
+    """
+    rcParams.update(rc_params_from_file(fname))
+
+
+class rc_context(object):
+    """
+    Return a context manager for managing rc settings.
+
+    This allows one to do::
+
+    >>> with mpl.rc_context(fname='screen.rc'):
+    >>>     plt.plot(x, a)
+    >>>     with mpl.rc_context(fname='print.rc'):
+    >>>         plt.plot(x, b)
+    >>>     plt.plot(x, c)
+    
+    The 'a' vs 'x' and 'c' vs 'x' plots would have settings from
+    'screen.rc', while the 'b' vs 'x' plot would have settings from
+    'print.rc'.
+
+    A dictionary can also be passed to the context manager::
+
+    >>> with mpl.rc_context(rc={'text.usetex': True}, fname='screen.rc'):
+    >>>     plt.plot(x, a)
+
+    The 'rc' dictionary takes precedence over the settings loaded from
+    'fname'.  Passing a dictionary only is also valid.
+    """
+
+    def __init__(self, rc=None, fname=None):
+        self.rcdict = rc
+        self.fname = fname
+    def __enter__(self):
+        self._rcparams = rcParams.copy()
+        if self.fname:
+            rc_file(self.fname)
+        if self.rcdict:
+            rcParams.update(self.rcdict)
+    def __exit__(self, type, value, tb):
+        rcParams.update(self._rcparams)
+
+
 def rc_file_defaults():
     """
     Restore the default rc params from the original matplotlib rc that
@@ -1017,6 +1068,7 @@ def tk_window_focus():
     'matplotlib.tests.test_mathtext',
     'matplotlib.tests.test_mlab',
     'matplotlib.tests.test_patches',
+    'matplotlib.tests.test_rcparams',
     'matplotlib.tests.test_simplification',
     'matplotlib.tests.test_spines',
     'matplotlib.tests.test_text',

lib/matplotlib/tests/test_rcparams.py

@@ -0,0 +1,38 @@
+import os
+
+import matplotlib as mpl
+mpl.rc('text', usetex=False)
+mpl.rc('lines', linewidth=22)
+
+fname = os.path.join(os.path.dirname(__file__), 'test_rcparams.rc')
+  
+def test_rcparams():
+
+    usetex = mpl.rcParams['text.usetex']
+    linewidth = mpl.rcParams['lines.linewidth']
+
+    # test context given dictionary
+    with mpl.rc_context(rc={'text.usetex': not usetex}):
+        assert mpl.rcParams['text.usetex'] == (not usetex)
+    assert mpl.rcParams['text.usetex'] == usetex
+
+    # test context given filename (mpl.rc sets linewdith to 33)
+    with mpl.rc_context(fname=fname):
+        assert mpl.rcParams['lines.linewidth'] == 33
+    assert mpl.rcParams['lines.linewidth'] == linewidth
+
+    # test context given filename and dictionary
+    with mpl.rc_context(fname=fname, rc={'lines.linewidth': 44}):
+        assert mpl.rcParams['lines.linewidth'] == 44
+    assert mpl.rcParams['lines.linewidth'] == linewidth
+
+    # test rc_file
+    try:
+        mpl.rc_file(fname)
+        assert mpl.rcParams['lines.linewidth'] == 33
+    finally:
+        mpl.rcParams['lines.linewidth'] = linewidth
+    
+
+if __name__ == '__main__':
+    test_rcparams()

lib/matplotlib/tests/test_rcparams.rc

@@ -0,0 +1,3 @@
+# this file is used by the tests in test_rcparams.py
+
+lines.linewidth: 33