import requests

root_url = "<root_uri>"

api = "/api/projectgroups/all"
headers = {'X-Octopus-ApiKey':'<key>'}
response = requests.get(root_url+api, headers=headers)
projectgroups = response.json()

for group in projectgroups:
    print group['Name']

    api = "/api/projectgroups/"+group['Id']+"/projects"
    response = requests.get(root_url+api, headers=headers)
    projects = response.json()

    for project in projects['Items']:
        print project['Name']