Merge pull request matplotlib#1031 from WeatherGod/errorbar_capthick

Added 'capthick' kwarg to errorbar()

doc/api/api_changes.rst

@@ -65,6 +65,13 @@ Changes in 1.2.x
   :class:`~matplotlib.colorbar.ColorbarBase` allows one to control the size of
   the triangular minimum and maximum extensions on colorbars.
 
+* A new keyword *capthick* in :meth:`~matplotlib.pyplot.errorbar` has been
+  added as an intuitive alias to the *markeredgewidth* and *mew* keyword
+  arguments, which indirectly controlled the thickness of the caps on
+  the errorbars.  For backwards compatibility, specifying either of the
+  original keyword arguments will override any value provided by
+  *capthick*.
+
 Changes in 1.1.x
 ================
 

examples/pylab_examples/errorbar_demo.py

@@ -39,7 +39,7 @@
 yerr_lower = y - ylower
 
 ax.errorbar(x, y, yerr=[yerr_lower, 2*yerr], xerr=xerr,
-                            fmt='o', ecolor='g')
+            fmt='o', ecolor='g', capthick=2)
 ax.set_title('Mixed sym., log y')
 
 fig.suptitle('Variable errorbars')

lib/matplotlib/axes.py

@@ -5179,14 +5179,16 @@ def pie(self, x, explode=None, labels=None, colors=None,
     def errorbar(self, x, y, yerr=None, xerr=None,
                  fmt='-', ecolor=None, elinewidth=None, capsize=3,
                  barsabove=False, lolims=False, uplims=False,
-                 xlolims=False, xuplims=False, errorevery=1, **kwargs):
+                 xlolims=False, xuplims=False, errorevery=1, capthick=None,
+                 **kwargs):
         """
         Call signature::
 
           errorbar(x, y, yerr=None, xerr=None,
                    fmt='-', ecolor=None, elinewidth=None, capsize=3,
                    barsabove=False, lolims=False, uplims=False,
-                   xlolims=False, xuplims=False)
+                   xlolims=False, xuplims=False, errorevery=1,
+                   capthick=None)
 
         Plot *x* versus *y* with error deltas in *yerr* and *xerr*.
         Vertical errorbars are plotted if *yerr* is not *None*.
@@ -5210,14 +5212,22 @@ def errorbar(self, x, y, yerr=None, xerr=None,
             errorbars to a bar plot, for example.
 
           *ecolor*: [ *None* | mpl color ]
-            a matplotlib color arg which gives the color the errorbar lines;
+            A matplotlib color arg which gives the color the errorbar lines;
             if *None*, use the marker color.
 
           *elinewidth*: scalar
-            the linewidth of the errorbar lines. If *None*, use the linewidth.
+            The linewidth of the errorbar lines. If *None*, use the linewidth.
 
           *capsize*: scalar
-            the size of the error bar caps in points
+            The length of the error bar caps in points
+
+          *capthick*: scalar
+            An alias kwarg to *markeredgewidth* (a.k.a. - *mew*). This
+            setting is a more sensible name for the property that
+            controls the thickness of the error bar cap in points. For
+            backwards compatibility, if *mew* or *markeredgewidth* are given,
+            then they will over-ride *capthick*.  This may change in future
+            releases.
 
           *barsabove*: [ *True* | *False* ]
             if *True*, will plot the errorbars above the plot
@@ -5268,7 +5278,7 @@ def errorbar(self, x, y, yerr=None, xerr=None,
         """
 
         if errorevery < 1:
-            raise ValueError('errorevery has to be a strictly positive integer ')
+            raise ValueError('errorevery has to be a strictly positive integer')
 
         self._process_unit_info(xdata=x, ydata=y, kwargs=kwargs)
         if not self._hold: self.cla()
@@ -5344,6 +5354,15 @@ def xywhere(xs, ys, mask):
             plot_kw = {
                 'ms':2*capsize,
                 'label':'_nolegend_'}
+            if capthick is not None:
+                # 'mew' has higher priority, I believe,
+                # if both 'mew' and 'markeredgewidth' exists.
+                # So, save capthick to markeredgewidth so that
+                # explicitly setting mew or markeredgewidth will
+                # over-write capthick.
+                plot_kw['markeredgewidth'] = capthick
+            # For backwards-compat, allow explicit setting of
+            # 'mew' or 'markeredgewidth' to over-ride capthick.
             if 'markeredgewidth' in kwargs:
                 plot_kw['markeredgewidth']=kwargs['markeredgewidth']
             if 'mew' in kwargs:

lib/matplotlib/pyplot.py

@@ -2533,7 +2533,8 @@ def csd(x, y, NFFT=256, Fs=2, Fc=0, detrend=mlab.detrend_none,
 @autogen_docstring(Axes.errorbar)
 def errorbar(x, y, yerr=None, xerr=None, fmt='-', ecolor=None, elinewidth=None,
              capsize=3, barsabove=False, lolims=False, uplims=False,
-             xlolims=False, xuplims=False, errorevery=1, hold=None, **kwargs):
+             xlolims=False, xuplims=False, errorevery=1, capthick=None,
+             hold=None, **kwargs):
     ax = gca()
     # allow callers to override the hold state by passing hold=True|False
     washold = ax.ishold()
@@ -2545,7 +2546,7 @@ def errorbar(x, y, yerr=None, xerr=None, fmt='-', ecolor=None, elinewidth=None,
                           elinewidth=elinewidth, capsize=capsize,
                           barsabove=barsabove, lolims=lolims, uplims=uplims,
                           xlolims=xlolims, xuplims=xuplims,
-                          errorevery=errorevery, **kwargs)
+                          errorevery=errorevery, capthick=capthick, **kwargs)
         draw_if_interactive()
     finally:
         ax.hold(washold)