'''
This file is part of PM4Py (More Info: https://pm4py.fit.fraunhofer.de).
PM4Py is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
PM4Py is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with PM4Py. If not, see <https://www.gnu.org/licenses/>.
'''
import copy
from pm4py.objects.petri_net.utils import petri_utils as pn_utils
from pm4py.objects.petri_net.obj import PetriNet
from typing import Optional, Dict, Any, Union, Tuple
def _short_circuit_petri_net(net):
"""
Creates a short circuited Petri net,
whether an unique source place and sink place are there,
by connecting the sink with the source
Parameters
---------------
net
Petri net
Returns
---------------
boolean
Boolean value
"""
s_c_net = copy.deepcopy(net)
no_source_places = 0
no_sink_places = 0
sink = None
source = None
for place in s_c_net.places:
if len(place.in_arcs) == 0:
source = place
no_source_places += 1
if len(place.out_arcs) == 0:
sink = place
no_sink_places += 1
if (sink is not None) and (source is not None) and no_source_places == 1 and no_sink_places == 1:
# If there is one unique source and sink place, short circuit Petri Net is constructed
t_1 = PetriNet.Transition("short_circuited_transition", "short_circuited_transition")
s_c_net.transitions.add(t_1)
# add arcs in short-circuited net
pn_utils.add_arc_from_to(sink, t_1, s_c_net)
pn_utils.add_arc_from_to(t_1, source, s_c_net)
return s_c_net
else:
return None
[docs]def apply(net: PetriNet, parameters: Optional[Dict[Any, Any]] = None) -> bool:
"""
Checks if a Petri net is a workflow net
Parameters
---------------
net
Petri net
parameters
Parameters of the algorithm
Returns
---------------
boolean
Boolean value
"""
if parameters is None:
parameters = {}
import networkx as nx
scnet = _short_circuit_petri_net(net)
if scnet is None:
return False
nodes = scnet.transitions | scnet.places
graph = nx.DiGraph()
while len(nodes) > 0:
element = nodes.pop()
graph.add_node(element.name)
for in_arc in element.in_arcs:
graph.add_node(in_arc.source.name)
graph.add_edge(in_arc.source.name, element.name)
for out_arc in element.out_arcs:
graph.add_node(out_arc.target.name)
graph.add_edge(element.name, out_arc.target.name)
if nx.algorithms.components.is_strongly_connected(graph):
return True
else:
return False