def get_phase_diagram(
cls, intersection: Intersection,
fixed_time_schedule: FixedTimeSchedule) -> PhaseDiagram:
"""
Get the phase diagram specifying the order in which the signal groups have their greenyellow intervals
in the fixed-time schedule
:param intersection: intersection for which to optimize the fts (contains signal groups, conflicts and more)
:param fixed_time_schedule: fixed-time schedule for which we want to retrieve the phase diagram.
:return: the associated phase diagram
IMPORTANT: we try to start the greenyellow intervals of two signal groups that are subject to a synchronous
start or a greenyellow-lead in the same phase; however, if this is not possible for all such pairs, then we try to
satisfy it for as many such pairs as possible.
For example consider the following theoretical problem where we have three signal groups:
sg1, sg2, and sg3. sg1 conflicts with sg2 and sg3. sg2 has a greenyellow_lead(min=30, max=50) w.r.t. sg3.
The following schedule is feasible
greenyellow_intervals = {"sg1": [[0, 10], [40, 50]], "sg2": [[20, 30]], "sg3": [[60,70]]}
period=80
However, it is not possible to find a phase diagram where sg2 and sg3 start in the same phase; only the
following phase diagram is possible: [[["sg1", 0]], [["sg2", 0]], [["sg1", 1]], [["sg3", 0]]]
"""
endpoint = f"{CLOUD_API_URL}/phase-diagram-computation"
headers = SwiftMobilityCloudApi.get_authentication_header()
# rest-api call
try:
json_dict = dict(
intersection=intersection.to_json(),
greenyellow_intervals=fixed_time_schedule.to_json()
["greenyellow_intervals"],
period=fixed_time_schedule.to_json()["period"])
logging.debug(f"calling endpoint {endpoint}")
r = requests.post(endpoint, json=json_dict, headers=headers)
logging.debug(f"finished calling endpoint {endpoint}")
except requests.exceptions.ConnectionError:
raise UnknownCloudException(CONNECTION_ERROR_MSG)
# check for errors
check_status_code(response=r)
output = r.json()
# parse output
phase_diagram = PhaseDiagram.from_json(output["phase_diagram"])
return phase_diagram
def test_json_back_and_forth(self) -> None:
""" test converting back and forth from and to json """
# GIVEN
input_dict = TestFTSInputValidation.get_default_inputs()
# WHEN
fixed_time_schedule = FixedTimeSchedule(**input_dict)
# THEN converting back and forth should in the end give the same result
fts_dict = fixed_time_schedule.to_json()
fts_from_json = FixedTimeSchedule.from_json(fts_dict=fts_dict)
self.assertDictEqual(fts_dict, fts_from_json.to_json())
def evaluate_fts(
cls,
intersection: Intersection,
arrival_rates: ArrivalRates,
fixed_time_schedule: FixedTimeSchedule,
horizon: float = 2.0,
initial_queue_lengths: Optional[QueueLengths] = None) -> KPIs:
"""
Evaluate a fixed-time schedule; returns KPIs (estimated delay experienced by road users and the capacity (
see also KPIs and the SwiftMobilityCloudApi.get_optimized_fts() method for their definition.
:param intersection: intersection for which to optimize the fts (contains signal groups, conflicts and more)
:param arrival_rates: arrival rates; each arrival rate is specified in personal car equivalent per hour (PCE/h)
cyclists per hour or pedestrians per hour
:param fixed_time_schedule:
:param initial_queue_lengths: initial amount of traffic waiting at each of the traffic lights; if None, then we
assume no initial traffic.
:param horizon: time period of interest in hours.
:return KPIs, which are the estimated
"""
assert horizon >= 1, HORIZON_LB_EXCEEDED_MSG
if initial_queue_lengths is None:
# assume no initial traffic
initial_queue_lengths = QueueLengths({
signalgroup.id: [0] * len(signalgroup.traffic_lights)
for signalgroup in intersection.signalgroups
})
check_all_arrival_rates_and_queue_lengths_specified(
intersection=intersection,
arrival_rates=arrival_rates,
initial_queue_lengths=initial_queue_lengths)
endpoint = f"{CLOUD_API_URL}/fts-evaluation"
headers = SwiftMobilityCloudApi.get_authentication_header()
# rest-api call
try:
# assume that the traffic that is initially present arrives during the horizon.
corrected_arrival_rates = arrival_rates + initial_queue_lengths / horizon
json_dict = dict(intersection=intersection.to_json(),
arrival_rates=corrected_arrival_rates.to_json(),
fixed_time_schedule=fixed_time_schedule.to_json())
logging.debug(f"calling endpoint {endpoint}")
r = requests.post(endpoint, json=json_dict, headers=headers)
logging.debug(f"finished calling endpoint {endpoint}")
except requests.exceptions.ConnectionError:
raise UnknownCloudException(CONNECTION_ERROR_MSG)
# check for errors
check_status_code(response=r)
return KPIs.from_json(r.json())
def get_tuned_fts(cls, intersection: Intersection, arrival_rates: ArrivalRates,
fixed_time_schedule: FixedTimeSchedule, horizon: float = 2.0,
min_period_duration: float = 0.0, max_period_duration: float = 180,
objective: ObjectiveEnum = ObjectiveEnum.min_delay,
initial_queue_lengths: Optional[QueueLengths] = None) \
-> Tuple[FixedTimeSchedule, float]:
"""
Tune a fixed-time schedule; tune the greenyellow times to a new situation but keep the 'structure' of this
fixed-time schedule the same (the phase diagram remains the same).
:param intersection: intersection for which to optimize the fts (contains signal groups, conflicts and more)
:param arrival_rates: arrival rates; each arrival rate is specified in personal car equivalent per hour (PCE/h)
cyclists per hour or pedestrians per hour
:param fixed_time_schedule: fixed-time schedule to tune.
:param horizon: time period of interest in hours.
:param min_period_duration: minimum period duration of the fixed-time schedule in seconds
:param max_period_duration: minimum period duration of the fixed-time schedule in seconds
:param objective: what kpi (key performance indicator) to optimize. The following options are available:
- ObjectiveEnum.min_delay: minimize the delay experienced by road users arriving at the intersection during
the next 'horizon' hours. The initially waiting traffic is modeled as implicitly by increasing the
arrival rate by initial_queue_length / horizon PCE/h; this implies that we assume that this traffic is arriving
(evenly spread) during the horizon.
- ObjectiveEnum.min_period: search for the fixed-time schedule with the smallest period duration for which
all traffic lights are 'stable', i.e., the greenyellow interval is large enough so that the amount of traffic
that can (on average) depart during the horizon exceeds the traffic that arrives during
the horizon (+ initially waiting traffic).
- ObjectiveEnum.max_capacity: search for the fixed-time schedule that can handle the largest (percentual)
increase in traffic (including the initial amount of traffic), i.e., the largest percentual increase in traffic
for which all traffic lights are 'stable' (see also ObjectiveEnum.min_period).
:param initial_queue_lengths: initial amount of traffic waiting at each of the traffic lights; if None, then we
assume no initial traffic. The unit of each queue-length should align with the unit used for the arrival rate;
if the arrival rate is specified in PCE/h then the queue-length needs to be specified in PCE.
:return: fixed-time schedule, associated phase diagram and the objective value
(minimized delay, minimized period, or maximum percentual increase in traffic divided by 100, e.g. 1 means
currently at the verge of stability)
"""
assert horizon >= 1, HORIZON_LB_EXCEEDED_MSG
if initial_queue_lengths is None:
# assume no initial traffic
initial_queue_lengths = QueueLengths({
signalgroup.id: [0] * len(signalgroup.traffic_lights)
for signalgroup in intersection.signalgroups
})
check_all_arrival_rates_and_queue_lengths_specified(
intersection=intersection,
arrival_rates=arrival_rates,
initial_queue_lengths=initial_queue_lengths)
endpoint = f"{CLOUD_API_URL}/fts-tuning"
headers = SwiftMobilityCloudApi.get_authentication_header()
# rest-api call
try:
# assume that the traffic that is initially present arrives during the horizon.
corrected_arrival_rates = arrival_rates + initial_queue_lengths / horizon
json_dict = dict(intersection=intersection.to_json(),
fixed_time_schedule=fixed_time_schedule.to_json(),
arrival_rates=corrected_arrival_rates.to_json(),
min_period_duration=min_period_duration,
max_period_duration=max_period_duration,
objective=objective.value)
logging.debug(f"calling endpoint {endpoint}")
r = requests.post(endpoint, json=json_dict, headers=headers)
logging.debug(f"finished calling endpoint {endpoint}")
except requests.exceptions.ConnectionError:
raise UnknownCloudException(CONNECTION_ERROR_MSG)
# check for errors
check_status_code(response=r)
# parse output
output = r.json()
objective_value = output["obj_value"]
fixed_time_schedule = FixedTimeSchedule.from_json(
output["fixed_time_schedule"])
# check if safety restrictions are satisfied; raises a SafetyViolation-exception if this is not the case.
validate_safety_restrictions(intersection=intersection,
fixed_time_schedule=fixed_time_schedule)
return fixed_time_schedule, objective_value