def compute_departure_timestamp(df):
hours = df.CRSDepTime // 100
hours_timedelta = pd.to_timedelta(hours, unit='h')
minutes = df.CRSDepTime % 100
minutes_timedelta = pd.to_timedelta(minutes, unit='m')
return df.Date + hours_timedelta + minutes_timedelta
departure_timestamp = df.map_partitions(compute_departure_timestamp)
