Merge branch 'PMPY-1679' into 'integration'

PMPY-1679 Fix problem with empty OCEL definition (standard constructor)

See merge request process-mining/pm4py/pm4py-core!643

pm4py/objects/ocel/obj.py

@@ -16,22 +16,9 @@ class Parameters(Enum):
 
 class OCEL(object):
     def __init__(self, events=None, objects=None, relations=None, globals=None, parameters=None):
-        if events is None:
-            events = pd.DataFrame()
-        if objects is None:
-            objects = pd.DataFrame()
-        if relations is None:
-            relations = pd.DataFrame()
-        if globals is None:
-            globals = {}
         if parameters is None:
             parameters = {}
 
-        self.events = events
-        self.objects = objects
-        self.relations = relations
-        self.globals = globals
-
         self.event_id_column = exec_utils.get_param_value(Parameters.EVENT_ID, parameters, constants.DEFAULT_EVENT_ID)
         self.object_id_column = exec_utils.get_param_value(Parameters.OBJECT_ID, parameters,
                                                            constants.DEFAULT_OBJECT_ID)
@@ -43,6 +30,22 @@ def __init__(self, events=None, objects=None, relations=None, globals=None, para
         self.event_timestamp = exec_utils.get_param_value(Parameters.EVENT_TIMESTAMP, parameters,
                                                           constants.DEFAULT_EVENT_TIMESTAMP)
 
+        if events is None:
+            events = pd.DataFrame({self.event_id_column: [], self.event_activity: [], self.event_timestamp: []})
+        if objects is None:
+            objects = pd.DataFrame({self.object_id_column: [], self.object_type_column: []})
+        if relations is None:
+            relations = pd.DataFrame(
+                {self.event_id_column: [], self.event_activity: [], self.event_timestamp: [], self.object_id_column: [],
+                 self.object_type_column: []})
+        if globals is None:
+            globals = {}
+
+        self.events = events
+        self.objects = objects
+        self.relations = relations
+        self.globals = globals
+
         self.parameters = parameters
 
     def get_extended_table(self, ot_prefix=constants.DEFAULT_OBJECT_TYPE_PREFIX_EXTENDED) -> pd.DataFrame:
@@ -73,7 +76,8 @@ def get_summary(self) -> str:
         ret.append("\n")
         ret.append("Activities occurrences: " + str(self.events[self.event_activity].value_counts().to_dict()))
         ret.append("\n")
-        ret.append("Object types occurrences (number of objects): " + str(self.objects[self.object_type_column].value_counts().to_dict()))
+        ret.append("Object types occurrences (number of objects): " + str(
+            self.objects[self.object_type_column].value_counts().to_dict()))
         ret.append("\n")
         ret.append(
             "Please use <THIS>.get_extended_table() to get a dataframe representation of the events related to the objects.")