How can I define / find self-generated variables in an iPython session?

Scenario: I often work in iPython "pylab" mode for interactive data analysis. During these sessions I create a lot of intermittent variables and sometimes I forget what I named, especially if the analysis session runs for several days (intermittently obviously).

Now the problem is that with the dir () command in this iPython session all the defined variables are displayed, but since this is a pylab session, many important numpy and matplotlib commands are in the global namespace and basically they are hopelessly finding my own defined variables on this huge list.

Is there a way to filter this for "imported" and created so that I can only see the manually created variables during this session?