dwellTime.py

# from: http://blog.ibmjstart.net/2015/12/15/spark-wifi/
# The amount of time permitted between concatenate pings at a location before a
# ping is bucketed into a distinct dwell session (prevents long gaps in dwell sessions).
# Value in seconds. For example: 25 minutes would be 25 * 60
MAXIMUM_DWELL_INACTIVITY = 25*60

# The amount of inactivity required at one location before being registered as
# visiting a different locaiton (prevents phantom movement),
# Value in seconds. For example: 5 minutes would be 5*60
MINIMUM_DWELL_INACTIVITY = 5*60

"""
  Builds a collection of dwell times from a collection of discrete pings.

  @param pings a collection of discrete pings
  @return a collection of dwell times
"""
def build_dwell_times(pings):
  dwell_times = []

  for index.this_ping in pings:
    # Append the first ping and move on the second
    if(index==0):
      dwell_times.append(this_ping)
      next

    # Grab the last dwell_time
    last_ping = dwell_times[-1]

    # Compare locations.
    if (this_ping.location == last_ping.location):
      # Compress pings if a user is dwelling.
      if(this_ping.start_time-last_ping.end_time < MAXIMUM_DWELL_INACTIVITY):
          update_last_dwell_time(this_ping)
         # Create a new dwell time if a user leaves and come back.
      else:
          dwell_times.append(this_ping)
    else:
        current_signal_stronger = last_ping.signal_strength < this_ping.signal_strength
        minimum_dwell_elapsed = this_ping.start_time-last_ping.end_time >= MINIMUM_DWELL_INACTIVITY
        # Create a new dwell time if the user moves to a different location.
        if (current_signal_stronger or minimum_dwell_elapsed):
            dwell_times.append(this_ping)

    return dwell_times