Reverting single file in SVN to a particular revision

I have a file as shown below in an SVN repo that I would like to revert to a previous version. What is the way to do this in SVN? I want only downgrade this particular file to an older version, not the whole repo.

Thanks.

$ svn log myfile.py
----------------------
r179 | xx | 2010-05-10

Change 3
----------------------
r175 | xx | 2010-05-08

Change 2
----------------------
r174 | xx | 2010-05-04

Initial

If you just want the old file in your working copy:

svn up -r 147 myfile.py

If you want to rollback, see this "How to return to an older version of our code in subversion?".

svn cat takes a revision arg too!

svn cat -r 175 mydir/myfile > mydir/myfile

svn revert filename 

this should revert a single file.