Source code for pm4py.algo.simulation.tree_generator.variants.ptandloggenerator

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from pm4py.objects.process_tree import obj
from pm4py.objects.process_tree import obj as pt_operator
from scipy.stats import triang as triangular
import string
import math
import itertools
from enum import Enum
from itertools import accumulate as _accumulate, repeat as _repeat
from bisect import bisect as _bisect
import random
from typing import Optional, Dict, Any, Union, Tuple
from string import ascii_lowercase
import itertools

[docs]def choices(population, weights=None, *, cum_weights=None, k=1): """Return a k sized list of population elements chosen with replacement. If the relative weights or cumulative weights are not specified, the selections are made with equal probability. """ n = len(population) if cum_weights is None: if weights is None: _int = int n += 0.0 # convert to float for a small speed improvement return [population[_int(random.random() * n)] for i in _repeat(None, k)] cum_weights = list(_accumulate(weights)) elif weights is not None: raise TypeError('Cannot specify both weights and cumulative weights') if len(cum_weights) != n: raise ValueError('The number of weights does not match the population') bisect = _bisect total = cum_weights[-1] + 0.0 # convert to float hi = n - 1 return [population[bisect(cum_weights, random.random() * total, 0, hi)] for i in _repeat(None, k)]
[docs]class Parameters(Enum): SEQUENCE = "sequence" CHOICE = "choice" PARALLEL = "parallel" LOOP = "loop" OR = "or" MODE = "mode" MIN = "min" MAX = "max" SILENT = "silent" DUPLICATE = "duplicate" NO_MODELS = "no_models"
[docs]def apply(parameters: Optional[Dict[Union[str, Parameters], Any]] = None) -> obj.ProcessTree: """ Generate a process tree using the PTAndLogGenerator approach (see the paper PTandLogGenerator: A Generator for Artificial Event Data) Parameters -------------- parameters Parameters of the algorithm, according to the paper: - Parameters.MODE: most frequent number of visible activities - Parameters.MIN: minimum number of visible activities - Parameters.MAX: maximum number of visible activities - Parameters.SEQUENCE: probability to add a sequence operator to tree - Parameters.CHOICE: probability to add a choice operator to tree - Parameters.PARALLEL: probability to add a parallel operator to tree - Parameters.LOOP: probability to add a loop operator to tree - Parameters.OR: probability to add an or operator to tree - Parameters.SILENT: probability to add silent activity to a choice or loop operator - Parameters.DUPLICATE: probability to duplicate an activity label - Parameters.NO_MODELS: number of trees to generate from model population """ if parameters is None: parameters = {} if not "mode" in parameters: parameters["mode"] = 20 if not "min" in parameters: parameters["min"] = 10 if not "max" in parameters: parameters["max"] = 30 if not "sequence" in parameters: parameters["sequence"] = 0.25 if not "choice" in parameters: parameters["choice"] = 0.25 if not "parallel" in parameters: parameters["parallel"] = 0.25 if not "loop" in parameters: parameters["loop"] = 0.25 if not "or" in parameters: parameters["or"] = 0.0 if not "silent" in parameters: parameters["silent"] = 0.2 if not "duplicate" in parameters: parameters["duplicate"] = 0 if not "no_models" in parameters: parameters["no_models"] = 1 no_models = parameters["no_models"] if no_models == 1: return GeneratedTree(parameters).generate() else: # if the generation of an higher number of models is required, # proceed to the generation of these and return a list of # process trees. ret = [] for i in range(no_models): ret.append(GeneratedTree(parameters).generate()) return ret
[docs]def assign_operator(operator): if operator == "choice": return pt_operator.Operator.XOR elif operator == "sequence": return pt_operator.Operator.SEQUENCE elif operator == "parallel": return pt_operator.Operator.PARALLEL elif operator == "or": return pt_operator.Operator.OR elif operator == "loop": return pt_operator.Operator.LOOP else: return None
[docs]class GeneratedTree(object): # are later used as labels alphabet = string.ascii_lowercase
[docs] def calculate_activity_distribution(self, mode, min, max): """ Here, the triangular function is used, since the parameters for this function are given in the paramterfile. However, this approach can be applied on other distribution functions as well. :param mode: Mode of the distribution :param min: Smallest number :param max: Highest number :return: Distribution object """ # manage the case where min = mode = max c = (mode - min + 10**-12) / (max - min + 10**-6) ret = triangular(c, loc=min, scale=max - min) return ret
[docs] def draw_random_number_from_distribution(self): return self.activity_distribution.rvs(1)[0]
[docs] def select_operator(self): # add root operator, if probabilities are high enough # ordering of operator computation is sequence, choice, parallel, loop, or operator = choices(["sequence", "choice", "parallel", "loop", "or"], [self.parameters["sequence"], self.parameters["choice"], self.parameters["parallel"], self.parameters["loop"], self.parameters["or"]]) return operator[0]
[docs] def get_next_activity(self): result = self.iter.__next__() return result
[docs] def add_duplicates(self): """ Replaces some leaves to add duplicated labels. Depends on parameter. :return: """ duplication_allowed = False leaves = self.tree._get_leaves() for leaf in leaves: if leaf._parent != self.tree._get_root(): duplication_allowed = True break # if there is at least a depth of two if duplication_allowed: # list that contains the leaves with a label unequal to tau leaves_with_label = [] for leaf in leaves: if leaf.label is not None: leaves_with_label.append(leaf) # generate random list of duplicates duplicates = [] for leaf in leaves: if random.random() < self.parameters["duplicate"]: duplicates.append(leaf) if len(duplicates) > 0: # select potential leaves to replace them by duplicates possible_replacements = [] for leaf in leaves: if leaf not in duplicates: possible_replacements.append(leaf) for leaf in duplicates: i = 0 siblings = [] # determine sibling nodes (same parent) p = leaf._parent for child in p._children: if child != leaf: siblings.append(child) # TODO Skaling? Original: 30times, my idea : percentage of duplicates * len(leaves) while i < self.parameters["duplicate"] * len(leaves): replacement = random.choice(possible_replacements) if replacement not in siblings: replacement._label = leaf._label break
[docs] def add_node(self): leaves = self.tree._get_leaves() if self.tree.operator is None: leaves.append(self.tree) visible_leaves = [x for x in leaves if x.label is not None] operator = self.select_operator() op_map = {"parallel": obj.Operator.PARALLEL, "sequence": obj.Operator.SEQUENCE, "choice": obj.Operator.XOR, "loop": obj.Operator.LOOP, "or": obj.Operator.OR} mapped_operator = op_map[operator] order = random.randrange(0, 2) chosen_leaf = random.choice(leaves) added_count = 0 label1 = chosen_leaf.label if chosen_leaf.label is None: added_count = added_count + 1 label1 = self.get_next_activity() label2 = None if chosen_leaf.parent is None: self.tree = obj.ProcessTree(operator=mapped_operator) chosen_leaf = self.tree else: parent = chosen_leaf.parent del parent.children[parent.children.index(chosen_leaf)] chosen_leaf = obj.ProcessTree(operator=mapped_operator, parent=parent) parent.children.append(chosen_leaf) r = random.random() if self.total_activities - len(visible_leaves) > added_count and not r < self.parameters["silent"]: label2 = self.get_next_activity() node1 = obj.ProcessTree(label=label1, parent=chosen_leaf) node2 = obj.ProcessTree(label=label2, parent=chosen_leaf) if order == 0: chosen_leaf.children.append(node1) chosen_leaf.children.append(node2) elif order == 1: chosen_leaf.children.append(node2) chosen_leaf.children.append(node1)
[docs] def iter_all_strings(self): for size in itertools.count(1): for s in itertools.product(ascii_lowercase, repeat=size): yield "".join(s)
[docs] def create_process_tree(self): self.iter = self.iter_all_strings() self.tree = obj.ProcessTree() visible_leaves = [x for x in self.tree._get_leaves() if x.label is not None] while len(visible_leaves) < self.total_activities: self.add_node() visible_leaves = [x for x in self.tree._get_leaves() if x.label is not None]
def __init__(self, parameters): self.parameters = {} for param in parameters: p = param if type(param) is str else param.value self.parameters[p] = parameters[param] # rescale probabilities of operators if the sum is not equal to one if self.parameters["sequence"] + self.parameters["choice"] + self.parameters["parallel"] + self.parameters[ "loop"] + self.parameters["or"] != 1: sum_of_operators = self.parameters["sequence"] + self.parameters["choice"] + self.parameters["parallel"] + \ self.parameters["loop"] + self.parameters["or"] self.parameters["sequence"] = self.parameters["sequence"] / sum_of_operators self.parameters["choice"] = self.parameters["choice"] / sum_of_operators self.parameters["parallel"] = self.parameters["parallel"] / sum_of_operators self.parameters["or"] = self.parameters["or"] / sum_of_operators self.parameters["loop"] = self.parameters["loop"] / sum_of_operators # First step: Compute acivity distribution # Since mode, min and max are given, the triangle distribution is chosen self.activity_distribution = self.calculate_activity_distribution(self.parameters["mode"], self.parameters["min"], self.parameters["max"]) # Number of total activities represented in the tree. Also, tau is counted as an activity. self.total_activities = int(round(self.draw_random_number_from_distribution()))
[docs] def generate(self): # Create a process tree based on the given probabilities self.create_process_tree() # add duplicates self.add_duplicates() return self.tree