numpy.dot

I should have known. numpy.dot doesn't work with sparse matrices. What's worse is that it happily accepts a sparse matrix as an argument and yields some convoluted array of sparse matrices. What I should be doing is x.dot(y) where x is a scipy.sparse.sparse.spmatrix and y is a numpy.ndarray.

Note that I'm using the Debian stable versions of these packages: numpy 1.1.0 and scipy 0.6.0.

urllib2.HTTPErrorProcessor

With code similar to that I posed in Asynchronous HTTP Request, I was occasionally getting empty responses to my requests. When I added urllib2.HTTPErrorProcessor to the inheritance list for MyHandler, the problem went away. My guess is the server was generating a 503 Service Unavailable responses and my client code wasn't handling it. How one was supposed to know to do this from the documentation, I am unsure. I'm guessing that if the server might provide a redirect for your url, you would also want to inherit from urllib2.HTTPRedirectHandler.