Why does this AttributeError in python occur?
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.)
AttributeError is raised when attribute of the object is not available.
An attribute reference is a primary followed by a period and a name:
attributeref ::= primary "." identifier
To return a list of valid attributes for that object, use dir(), e.g.:
dir(scipy)So probably you need to do simply: import scipy.sparse