check for existence of plt.streamplot, fix docstring.

Author: Jeff Whitaker

examples/streamplot_demo.py

@@ -1,11 +1,14 @@
-# example showing how to use Line Integral Convolution to visualize a vector
-# flow field (from Hurricane Earl).  Produces something akin to streamlines.
-# Requires vectorplot scikit (http://scikits.appspot.com/vectorplot).
+# example showing how to use streamlines to visualize a vector
+# flow field (from Hurricane Earl).  
+# Requires matplotlib 1.1.1 or newer.
 from netCDF4 import Dataset as NetCDFFile
 from mpl_toolkits.basemap import Basemap, interp
 import numpy as np
 import matplotlib.pyplot as plt
 
+if not hasattr(plt, 'streamplot'):
+    raise ValueError('need newer version of matplotlib to run this example')
+
 # H*wind data from http://www.aoml.noaa.gov/hrd/data_sub/wind.html
 ncfile = NetCDFFile('rita.nc')
 udat = ncfile.variables['sfc_u'][0,:,:]