picasa gdata API and face recognition

Tonight I wanted to download a list of photos from picasaweb with a particular person in them, using the "subjectids" field. I don't see any official way to do this, but here's how I managed it:

In picasaweb (in my web browser), I loaded up the page showing all the photos my friend was in. At the bottom, there was a little "RSS" link. That link looked like this:

http://picasaweb.google.com/data/feed/base/user/credentiality?alt=rss&kind=photo&subjectids=SOME_BIG_LONG_STRING_OF_CHARACTERS&authkey=A_SHORTER_STRING&hl=en_US

I loaded that link in my browser, and it gave me the option to keep it as a live bookmark.

Instead, I trimmed the URL down and plunked it in this little python gdata script:

#!/usr/bin/python

import gdata.photos.service
import gdata.media
import gdata.geo

gd_client = gdata.photos.service.PhotosService()

gd_client.email = 'MY_EMAIL_ADDRESS'
gd_client.password = 'MY_PASSWORD'
gd_client.source = 'exampleCo-exampleApp-1'
gd_client.ProgrammaticLogin()

print "logged in"

photos = gd_client.GetFeed('/data/feed/base/user/credentiality?kind=photo&subjectids=THE_SAME_BIG_LONG_STRING')

for photo in photos.entry:
  print photo.content.src

That printed out a list of URLs to the images I wanted.