Cleanup and move errorbar_demo.

Split demo in to two different examples
matplotlib · tonysyu · Dec 18, 2012 · Dec 18, 2012 · Dec 18, 2012 · Dec 18, 2012
commit 7f1887b916ee21f96a49fed60d73b5e306e2287c
diff --git a/examples/pylab_examples/errorbar_demo.py b/examples/pylab_examples/errorbar_demo.py
diff --git a/examples/statistics/errorbar_demo.py b/examples/statistics/errorbar_demo.py
@@ -0,0 +1,13 @@
+"""
+Demo of the errorbar function.
+"""
+import numpy as np
+import matplotlib.pyplot as plt
+
+# example data
+x = np.arange(0.1, 4, 0.5)
+y = np.exp(-x)
+
+plt.errorbar(x, y, xerr=0.2, yerr=0.4)
+plt.show()
+
diff --git a/examples/statistics/errorbar_demo_features.py b/examples/statistics/errorbar_demo_features.py
@@ -0,0 +1,39 @@
+"""
+Demo of errorbar function with different ways of specifying error bars.
+
+Errors can be specified as a constant value (as shown in `errorbar_demo.py`),
+or as demonstrated in this example, they can be specified by an N x 1 or 2 x N,
+where N is the number of data points.
+
+N x 1:
+    Error varies for each point, but the error values are symmetric (i.e. the
+    lower and upper values are equal).
+
+2 x N:
+    Error varies for each point, and the lower and upper limits (in that order)
+    are different (asymmetric case)
+
+In addition, this example demonstrates how to use log scale with errorbar.
+"""
+import numpy as np
+import matplotlib.pyplot as plt
+
+# example data
+x = np.arange(0.1, 4, 0.5)
+y = np.exp(-x)
+# example error bar values that vary with x-position
+error = 0.1 + 0.2 * x
+# error bar values w/ different -/+ errors
+lower_error = 0.4 * error
+upper_error = error
+asymmetric_error = [lower_error, upper_error]
+
+fig, (ax0, ax1) = plt.subplots(nrows=2, sharex=True)
+ax0.errorbar(x, y, yerr=error, fmt='-o')
+ax0.set_title('variable, symmetric error')
+
+ax1.errorbar(x, y, xerr=asymmetric_error, fmt='o')
+ax1.set_title('variable, asymmetric error')
+ax1.set_yscale('log')
+plt.show()
+