@property<EOL><INDENT>def density(self):<DEDENT>
r = float(self.sp_index.npoints) / float(self.sp_index.length)<EOL>return r<EOL>
The percent of non- ``fill_value`` points, as decimal.

Examples
--------
>>> s = SparseArray([0, 0, 1, 1, 1], fill_value=0)
>>> s.density
0.6