plot join date launchpad team

You can do this using Launchpad API.

#!/usr/bin/python
from launchpadlib.launchpad import Launchpad

# This script uses the API defined at:
# https://launchpad.net/+apidoc/devel.html

def team_join_dates():
    # Production is https://api.launchpad.net/. Use staging when
    # testing your script.
    lp = Launchpad.login_with(
        'teamjoined', 'https://api.staging.launchpad.net/')
    # Provide your team's launchpad ID. The ID is used in the URL.
    team = lp.people['launchpad-registry']
    for membership in team.members_details:
        joined = membership.date_joined.strftime('%Y-%m-%d')
        user = membership.member
        if user.team_owner is not None:
            # The user is actually a team, all the members joined at the
            # same time.
            for member in user.members:
                print '%s, %s' % (member.displayname, joined)
        else:
            # The user is a user.
            print '%s, %s' % (user.displayname, joined)

if __name__ == '__main__':
    team_join_dates()

I tried the script above, and I get this error:

python plot_join_date_launchpad.py
Traceback (most recent call last):
  File "plot_join_date_launchpad.py", line 29, in <module>
    team_join_dates()
  File "plot_join_date_launchpad.py", line 26, in team_join_dates
    print '%s, %s' % (user.displayname, joined)
  File "/usr/lib/python2.7/dist-packages/lazr/restfulclient/resource.py", line 673, in __getattr__
    return super(Entry, self).__getattr__(name)
  File "/usr/lib/python2.7/dist-packages/lazr/restfulclient/resource.py", line 319, in __getattr__
    % (self.__class__.__name__, attr))
AttributeError: 'Entry' object has no attribute 'displayname'
avilella@magneto:~/data/python_playfulness$ python plot_join_date_launchpad.py
Traceback (most recent call last):
  File "plot_join_date_launchpad.py", line 29, in <module>
    team_join_dates()
  File "plot_join_date_launchpad.py", line 15, in team_join_dates
    team = lp.people['launchpad-registry']
  File "/usr/lib/python2.7/dist-packages/lazr/restfulclient/resource.py", line 935, in __getitem__
    raise KeyError(key)
KeyError: 'launchpad-registry'

It should be display_name rather than displayname.

launchpad-registry is not a real team, you are expected to replace this with the id of a team you are interested in.