This happens because the scipy
module doesn't have any attribute named sparse
. That attribute only gets defined when you import scipy.sparse
.
Submodules don't automatically get imported when you just import scipy
; you need to import them explicitly. The same holds for most packages, although a package can choose to import its own submodules if it wants to. (For example, if scipy/__init__.py
included a statement import scipy.sparse
, then the sparse
submodule would be imported whenever you import scipy
.)