Update a pip requirement with ViM

Need to update a requirement in vim. Dont want to copy the output for pip freeze or replace the file with the output for pip freeze.

In ViM select the line you want to update. With V

123 | django==1.3.1

Then go to command mode with :

<, >!pip freeze | grep django==

This will then update the requirement too

django==1.4.5