StackOverflow question #24975218

gistfile1.py

#!/usr/bin/python

class Person(object):
  def __init__(self, name, sup):
    self.name = name
    self.sup = sup

yesterday = [
  Person("Bill", "Sup A"),
  Person("Harry", "Sup A"),
  Person("Sally", "Sup A"),
  Person("John", "Sup D"),
  Person("Matt", "Sup D"),
  Person("Steve", "Sup N"),
  Person("Jen", "Sup N"),
  Person("Sue", "Sup N"),
  Person("Rob", "Sup N")
]

today = [
  Person("Bill", "Sup B"),
  Person("Harry", "Sup B"),
  Person("Sally", "Sup B"),
  Person("John", "Sup C"),
  Person("Matt", "Sup C"),
  Person("Steve", "Sup L"),
  Person("Jen", "Sup L"),
  Person("Sue", "Sup L"),
  Person("Rob", "Sup L")
]

def find_changed_supervisors(yesterday, today):
  people = {}
  for person in yesterday:
    people[person.name] = [person]
  for person in today:
    if person.name in people:
      people[person.name].append(person)
    else:
      people[person.name] = [person]

  super_changes = {}
  for person_name, person_objects in people.iteritems():
    if len(person_objects) != 2:
      continue
    yesterday_super = person_objects[0].sup
    today_super = person_objects[1].sup
    if yesterday_super == today_super:
      continue
    super_change = (yesterday_super, today_super)
    if super_change not in super_changes:
      super_changes[super_change] = []
    super_changes[super_change].append(person_name)

  for super_change, person_names in super_changes.iteritems():
    print "%s --> %s" % super_change
    print " ".join(person_names)
    print

if __name__ == '__main__':
  find_changed_supervisors(yesterday, today)