Parses the JSON events list for the <Trading Game> Mechanical Turk experiment

parse_events.py

import json

FIRST_MTURK = 1313994874
GAME_LENGTH = 5*60+5
START_CASH = 20.0
APPROVED_MTURK = ('25fead42', '5d7ef660', '23cf8ae3', '2d1402d1', '4c8f688c',
    '09be3a98', '682550c5', '3ce59c03')

def parse_events(fname):
  '''Takes a filename and parses all its events'''
  with open(fname, 'r') as fp:
    return extract_all(json.load(fp))

def extract_all(all_events):
  '''Takes the dictionary of users->events and returns a dictionary containing
  the users as keys and the useful lists in a tuple as values'''
  
  results = {}
  for user,events in all_events.items():
    if user not in APPROVED_MTURK:
      continue
    
    result = extract_data(events)
    if result is not None:
      results[user] = result
  
  return results

def extract_data(events):
  '''Generates four lists--time, wallet, value, and net worth--from a list of
  events. It first goes backward in time calculating the wallet and change in
  value. Then it works from start to finish calculating the actual value. Next,
  it goes through again and determines net worth. Finally, it converts the
  timestamps to time since the start of the game.'''
  
  start = None
  end = None
  
  times = []
  deltavalues = []
  
  values = []
  wallet = []
  networth = []
  
  class Value:
    wallet = START_CASH
    value = 0.0
  value = Value()
  
  def add(time, netwallet=None, netvalue=None):
    times.append(time)
    
    if netwallet is not None:
      value.wallet += netwallet
    if netvalue is not None:
      value.value += netvalue
    
    values.append(value.value)
    wallet.append(value.wallet)
    networth.append(value.value + value.wallet)
  
  for event in reversed(events):
    event = json.loads(event)
    
    if event['name'] == 'Began game':
      start = event['time']
      add(start)
    
    elif event['name'] == 'EndGame':
      end = event['time']
      add(end)
    
    elif event['name'] == 'AuctionSold':
      add(event['time'], event['data']['price'], -event['data']['item']['value'])
    elif event['name'] == 'ItemBought':
      add(event['time'], -event['data']['price'], event['data']['item']['value'])
  
  if end is None or start is None:
    return None
  
  after_game = None
  before_game = 0
  # Convert timestamps
  for x,timestamp in enumerate(times):
    times[x] -= start
    if after_game is None and times[x] > GAME_LENGTH:
      after_game = x
    if times[x] < 0:
      before_game = x+1
    if before_game > 0 and after_game is not None:
      break
  
  # Remove any entries after the end of the game
  times = times[before_game:after_game]
  values = values[before_game:after_game]
  wallet = wallet[before_game:after_game]
  networth = networth [before_game:after_game]
  
  return (times, wallet, values, networth)