Merge branch 'errorbars' of https://github.com/chrodan/matplotlib into chrodan-errorbars

Conflicts:
	CHANGELOG

Author: WeatherGod

CHANGELOG

@@ -1,3 +1,6 @@
+2012-02-29 errorevery keyword added to errorbar to enable errorbar
+           subsampling. fixes issue #600.
+
 2012-01-08 Add axes.streamplot to plot streamlines of a velocity field.
 		   Adapted from Tom Flannaghan streamplot implementation. -TSY
 

examples/pylab_examples/errorbar_subsample.py

@@ -0,0 +1,30 @@
+'''
+Demo for the errorevery keyword to show data full accuracy data plots with
+few errorbars.
+'''
+
+import numpy as np
+import matplotlib.pyplot as plt
+
+# example data
+x = np.arange(0.1, 4, 0.1)
+y = np.exp(-x)
+
+# example variable error bar values
+yerr = 0.1 + 0.1*np.sqrt(x)
+
+
+# Now switch to a more OO interface to exercise more features.
+fig, axs = plt.subplots(nrows=1, ncols=2, sharex=True)
+ax = axs[0]
+ax.errorbar(x, y, yerr=yerr)
+ax.set_title('all errorbars')
+
+ax = axs[1]
+ax.errorbar(x, y, yerr=yerr, errorevery=5)
+ax.set_title('only every 5th errorbar')
+
+
+fig.suptitle('Errorbar subsampling for better visualibility')
+
+plt.show()

lib/matplotlib/axes.py

@@ -5108,7 +5108,7 @@ 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, **kwargs):
+                 xlolims=False, xuplims=False, errorevery=1, **kwargs):
         """
         call signature::
 
@@ -5157,6 +5157,11 @@ def errorbar(self, x, y, yerr=None, xerr=None,
             only upper/lower limits. In that case a caret symbol is
             used to indicate this. lims-arguments may be of the same
             type as *xerr* and *yerr*.
+            
+          *errorevery*: positive integer
+            subsamples the errorbars. Eg if everyerror=5, errorbars for every
+            5-th datapoint will be plotted. The data plot itself still shows
+            all data points.
 
         All other keyword arguments are passed on to the plot command for the
         markers. For example, this code makes big red squares with
@@ -5191,6 +5196,9 @@ def errorbar(self, x, y, yerr=None, xerr=None,
 
         """
 
+        if errorevery < 1:
+            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()
         holdstate = self._hold
@@ -5247,6 +5255,8 @@ def errorbar(self, x, y, yerr=None, xerr=None,
         if not iterable(xuplims): xuplims = np.array([xuplims]*len(x), bool)
         else: xuplims = np.asarray(xuplims, bool)
 
+        everymask = np.arange(len(x)) % errorevery == 0
+
         def xywhere(xs, ys, mask):
             """
             return xs[mask], ys[mask] where mask is True but xs and
@@ -5285,33 +5295,38 @@ def xywhere(xs, ys, mask):
                 right  = [thisx+thiserr for (thisx, thiserr)
                           in cbook.safezip(x,xerr)]
 
-            barcols.append( self.hlines(y, left, right, **lines_kw ) )
+            yo, _ = xywhere(y, right, everymask)
+            lo, ro= xywhere(left, right, everymask)
+            barcols.append( self.hlines(yo, lo, ro, **lines_kw ) )
             if capsize > 0:
                 if xlolims.any():
                     # can't use numpy logical indexing since left and
                     # y are lists
-                    leftlo, ylo = xywhere(left, y, xlolims)
+                    leftlo, ylo = xywhere(left, y, xlolims & everymask)
 
                     caplines.extend(
                         self.plot(leftlo, ylo, ls='None',
                                   marker=mlines.CARETLEFT, **plot_kw) )
                     xlolims = ~xlolims
-                    leftlo, ylo = xywhere(left, y, xlolims)
+                    leftlo, ylo = xywhere(left, y, xlolims & everymask)
                     caplines.extend( self.plot(leftlo, ylo, 'k|', **plot_kw) )
                 else:
-                    caplines.extend( self.plot(left, y, 'k|', **plot_kw) )
+                    
+                    leftlo, ylo = xywhere(left, y, everymask)
+                    caplines.extend( self.plot(leftlo, ylo, 'k|', **plot_kw) )
 
                 if xuplims.any():
 
-                    rightup, yup = xywhere(right, y, xuplims)
+                    rightup, yup = xywhere(right, y, xuplims & everymask)
                     caplines.extend(
                         self.plot(rightup,  yup, ls='None',
                                   marker=mlines.CARETRIGHT, **plot_kw) )
                     xuplims = ~xuplims
-                    rightup, yup = xywhere(right, y, xuplims)
+                    rightup, yup = xywhere(right, y, xuplims & everymask)
                     caplines.extend( self.plot(rightup,  yup, 'k|', **plot_kw) )
                 else:
-                    caplines.extend( self.plot(right, y, 'k|', **plot_kw) )
+                    rightup, yup = xywhere(right, y, everymask)
+                    caplines.extend( self.plot(rightup,  yup, 'k|', **plot_kw) )
 
         if yerr is not None:
             if (iterable(yerr) and len(yerr)==2 and
@@ -5328,31 +5343,35 @@ def xywhere(xs, ys, mask):
                 upper  = [thisy+thiserr for (thisy, thiserr)
                           in cbook.safezip(y,yerr)]
 
-            barcols.append( self.vlines(x, lower, upper, **lines_kw) )
+            xo, _ = xywhere(x, lower, everymask)
+            lo, uo= xywhere(lower, upper, everymask)
+            barcols.append( self.vlines(xo, lo, uo, **lines_kw) )
             if capsize > 0:
 
                 if lolims.any():
-                    xlo, lowerlo = xywhere(x, lower, lolims)
+                    xlo, lowerlo = xywhere(x, lower, lolims & everymask)
                     caplines.extend(
                         self.plot(xlo, lowerlo, ls='None',
                                   marker=mlines.CARETDOWN, **plot_kw) )
                     lolims = ~lolims
-                    xlo, lowerlo = xywhere(x, lower, lolims)
+                    xlo, lowerlo = xywhere(x, lower, lolims & everymask)
                     caplines.extend( self.plot(xlo, lowerlo, 'k_', **plot_kw) )
                 else:
-                    caplines.extend( self.plot(x, lower, 'k_', **plot_kw) )
+                    xlo, lowerlo = xywhere(x, lower, everymask)
+                    caplines.extend( self.plot(xlo, lowerlo, 'k_', **plot_kw) )
 
                 if uplims.any():
-                    xup, upperup = xywhere(x, upper, uplims)
+                    xup, upperup = xywhere(x, upper, uplims & everymask)
 
                     caplines.extend(
                         self.plot(xup, upperup, ls='None',
                                   marker=mlines.CARETUP, **plot_kw) )
                     uplims = ~uplims
-                    xup, upperup = xywhere(x, upper, uplims)
+                    xup, upperup = xywhere(x, upper, uplims & everymask)
                     caplines.extend( self.plot(xup, upperup, 'k_', **plot_kw) )
                 else:
-                    caplines.extend( self.plot(x, upper, 'k_', **plot_kw) )
+                    xup, upperup = xywhere(x, upper, everymask)
+                    caplines.extend( self.plot(xup, upperup, 'k_', **plot_kw) )
 
         if not barsabove and fmt is not None:
             l0, = self.plot(x,y,fmt,**kwargs)

lib/matplotlib/pyplot.py

@@ -2237,15 +2237,15 @@ def csd(x, y, NFFT=256, Fs=2, Fc=0, detrend=mlab.detrend_none, window=mlab.windo
 # This function was autogenerated by boilerplate.py.  Do not edit as
 # changes will be lost
 @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, hold=None, **kwargs):
+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):
     ax = gca()
     # allow callers to override the hold state by passing hold=True|False
     washold = ax.ishold()
 
     if hold is not None:
         ax.hold(hold)
     try:
-        ret = ax.errorbar(x, y, yerr, xerr, fmt, ecolor, elinewidth, capsize, barsabove, lolims, uplims, xlolims, xuplims, **kwargs)
+        ret = ax.errorbar(x, y, yerr, xerr, fmt, ecolor, elinewidth, capsize, barsabove, lolims, uplims, xlolims, xuplims, errorevery, **kwargs)
         draw_if_interactive()
     finally:
         ax.hold(washold)