Ropevim, rope in vim
Use https://github.com/klen/python-mode. It`s more new and powerful plugin.
Ropevim is a vim mode that allows you to use the rope library in vim to provide features like python refactorings and code-assists.
Just copy the plugin folders into your ~/.vim directory.
Alternatively, if you are using pathogen, clone the plugin into your bundle folder.
By default, rope auto assist is mapped to Control+Space. You can remap it. For example:
imap <buffer><Tab> <M-/>