Added step plot based on patch by Manuel Metz

efiring · efiring · commit 148913042dd6 · 2007-08-26T06:56:07.000Z
svn path=/trunk/matplotlib/; revision=3737
diff --git a/boilerplate.py b/boilerplate.py
@@ -80,6 +80,7 @@ def %(func)s(*args, **kwargs):
     'specgram',
     'spy',
     'stem',
+    'step',
     'vlines',
     'quiver',
     'quiverkey',
diff --git a/examples/masked_demo.py b/examples/masked_demo.py
@@ -6,15 +6,15 @@
 break the line at the data gaps.
 '''
 
-import matplotlib.numerix.ma as M
+import matplotlib.numerix.npyma as ma
 from pylab import *
 
-x = M.arange(0, 2*pi, 0.02)
-y = M.sin(x)
+x = ma.arange(0, 2*pi, 0.02)
+y = ma.sin(x)
 y1 = sin(2*x)
 y2 = sin(3*x)
-ym1 = M.masked_where(y1 > 0.5, y1)
-ym2 = M.masked_where(y2 < -0.5, y2)
+ym1 = ma.masked_where(y1 > 0.5, y1)
+ym2 = ma.masked_where(y2 < -0.5, y2)
 
 lines = plot(x, y, 'r', x, ym1, 'g', x, ym2, 'bo')
 setp(lines[0], linewidth = 4)
diff --git a/examples/step_demo.py b/examples/step_demo.py
@@ -0,0 +1,24 @@
+import numpy as npy
+from pylab import *
+
+x = npy.arange(1, 7, 0.4)
+y0 = npy.sin(x)
+y = y0.copy() + 2.5
+
+step(x, y, label='pre (default)')
+
+y -= 0.5
+step(x, y, where='mid', label='mid')
+
+y -= 0.5
+step(x, y, where='post', label='post')
+
+y = npy.ma.masked_where((y0>-0.15)&(y0<0.15), y - 0.5)
+step(x,y, label='masked (pre)')
+
+legend()
+
+xlim(0, 7)
+ylim(-0.5, 4)
+
+show()
diff --git a/lib/matplotlib/axes.py b/lib/matplotlib/axes.py
@@ -2964,6 +2964,58 @@ def get_handles():
 
     #### Specialized plotting
 
+    def step(self, x, y, *args, **kwargs):
+        '''
+        step(x, y, *args, **kwargs)
+
+        x and y must be 1-D sequences, and it is assumed, but not checked,
+        that x is uniformly increasing.
+
+        Make a step plot. The args and keyword args to step are the same
+        as the args to plot. See help plot for more info.
+
+        Additional keyword args for step:
+
+        * where: can be 'pre', 'post' or 'mid'; if 'pre', the
+                    interval from x[i] to x[i+1] has level y[i];
+                    if 'post', that interval has level y[i+1];
+                    and if 'mid', the jumps in y occur half-way
+                    between the x-values.  Default is 'pre'.
+        '''
+
+        where = kwargs.pop('where', 'pre')
+
+        if not cbook.iterable(x):
+            x = ma.array([x], dtype=npy.float_)
+        if not cbook.iterable(y):
+            y = ma.array([y], dtype=npy.float_)
+
+        if where=='pre':
+            x2 = ma.zeros((2*len(x)-1,), npy.float_)
+            y2 = ma.zeros((2*len(y)-1,), npy.float_)
+
+            x2[0::2], x2[1::2] = x, x[:-1]
+            y2[0::2], y2[1:-1:2] = y, y[1:]
+
+        elif where=='post':
+            x2 = ma.zeros((2*len(x)-1,), npy.float_)
+            y2 = ma.zeros((2*len(y)-1,), npy.float_)
+
+            x2[::2], x2[1:-1:2] = x, x[1:]
+            y2[0::2], y2[1::2] = y, y[:-1]
+
+        elif where=='mid':
+            x2 = ma.zeros((2*len(x),), npy.float_)
+            y2 = ma.zeros((2*len(y),), npy.float_)
+
+            x2[1:-1:2] = 0.5*(x[:-1]+x[1:])
+            x2[2::2] = 0.5*(x[:-1]+x[1:])
+            x2[0], x2[-1] = x[0], x[-1]
+
+            y2[0::2], y2[1::2] = y, y
+
+        return self.plot(x2, y2, *args, **kwargs)
+
 
     def bar(self, left, height, width=0.8, bottom=None,
             color=None, edgecolor=None, linewidth=None,
diff --git a/lib/matplotlib/pylab.py b/lib/matplotlib/pylab.py
