--- a
+++ b/ehrkit/classes.py
@@ -0,0 +1,214 @@
+"""Class definitions used in ehrkit.py"""
+from datetime import date
+
+class Patient:
+    """Patient with biographical and medical history data
+
+    Attributes:
+        id (int): unique patient ID
+        sex (str): patient sex ('M' or 'F')
+        dob (datetime): date of birth
+        dod (datetime): date of death
+        alive (bool): True if patient alive, else False
+    """
+
+    def __init__(self, data):
+        # Biographical Data:
+        if "id" in data:  #int
+            self.id = data["id"] #should we use pid in case of conflict with python keyword?
+        else:
+            self.id = None
+
+        if "sex" in data:
+            self.sex = data["sex"]
+        else:
+            self.sex = None
+
+        if "dob" in data:
+            self.dob = data["dob"]
+        else:
+            self.dob = None
+
+        if "dod" in data:
+            self.dod = data["dod"]
+        else:
+            self.dod = None
+
+        if "alive" in data:
+            self.alive = data["alive"]
+        else:
+            self.alive = None
+
+        ### MEDICAL DATA: ###
+        # Current patient diagnoses (Array of diagnosis objects)
+        if "diagnosis" in data:
+            self.diagnosis = data["diagnosis"]
+        else:
+            self.diagnosis = None
+        # Prescriptions patient is currently taking (Array of prescription objects)
+        if "current_prescriptions" in data:
+            self.prescriptions = data["current_prescriptions"]
+        else:
+            self.prescriptions = None
+        # Primary care provider (Foreign Key on Provider object):
+        if "primary_provider" in data:
+            self.primary_provider = data["primary_provider"]
+        else:
+            self.primary_provider = None
+        ### NOTEEVENTS data(list of nltk separated sentences):###
+        if "Text" in data:
+            self.note_events = data["Text"]
+        else:
+            self.note_events = None
+
+
+        ### MEDICAL HISTORY: ###
+        # 1.) Past prescriptions (Array of prescription objects)
+        if "past_prescriptions" in data:
+            self.prescriptHistory = data["past_prescriptions"]
+        else:
+            self.prescriptHistory = None
+        # 2.) Past diagnoses (Array of diagnosis objects)
+        if "past_diagnoses" in data:
+            self.diagHistory = data["past_diagnoses"]
+        else:
+            self.diagHistory = None
+        # 3) Procedures (Array of procedure objects)
+        if "procedures" in data:
+            self.procedures = data["procedures"]
+        else:
+            self.procedures = None
+    def addNE(self, textlist):
+        """List of all note events for patient, in tuple format (docID, content).
+        """
+        self.note_events = textlist
+
+    def addPrescriptions(self, textlist):
+        self.prescriptions = textlist
+
+    def diagnose(self, disease, start = None, end = None):
+        """Adds diagnosis to Patient history:"""
+        data = {"name": disease, "id": None, "start": start, "end": end}
+        newDiag = Diagnosis(data)
+        if not self.diagnosis: self.diagnosis = []
+        self.diagnosis.append(newDiag)
+
+    def add_procedure(self, procedure):
+        """Adds procedure to Patient history"""
+        data = {"name": procedure}
+        new_proc = Procedure(data)
+        if not self.procedures: self.procedures = []
+        self.procedures.append(new_proc)
+
+    def age(self):
+        """Compute patient age using birthdate"""
+        today = date.today()
+        birthdate = self.dob
+        return today.year - birthdate.year - ((today.month, today.day) < (birthdate.month, birthdate.day))
+
+
+# Disease Object
+
+class Disease:
+
+    def __init__(self, data):
+        self.name = data["name"]
+        # Foreign key for diagnosis object
+        self.id = data["id"]
+        # Symptoms — array of strings
+        self.symptoms = data["symptoms"]
+        self.abbreviation = data["abbreviations"]
+
+# Diagnosis Object
+# - Foreign Key on Disease Object
+
+class Diagnosis:
+
+    def __init__(self, data):
+        # Foreign key on disease object
+        self.name = data["name"]
+        # Date of diagnosis
+        self.start = data["start"]
+        # End date, if patient cured:
+        self.end = data["end"]
+
+# Prescription object
+
+class Prescription:
+
+    def __init__(self, data):
+        # Generic or Brand Name or Compound Name:
+        self.name = data["name"]
+        # Is there a standardized drug ID?
+        # This is important b/c patient could have
+        # been prescribed a generic
+        self.id = data["id"]
+        #Foreign key on patient object
+        self.patient_id = data["patient_id"]
+        self.indication = data["indication"]
+        # How often medicine is taken:
+        self.freq = data["frequency"]
+        #Unit of time for frequency (daily, weekly, monthly)
+        self.freq = data["frequency_unit"]
+        # Numerical quantity of dose — float
+        self.dosage = data["dosage"]
+        # Units of dosage (e.g. mg, ml, etc.) — str
+        self.units = data["dosage_units"]
+        self.start = data["start_date"]
+        self.end = data["end_date"]
+        # Not sure if need to record drug manufacturer — str
+        self.manufacturer = data["manufacturer"]
+        # Foreign key on Provider() object for prescriber:
+        self.prescriber_id = data["prescriber_id"]
+
+    # Length of prescription in days:
+    def duration(self):
+        if self.start == None and self.end == None:
+            return None
+
+        if self.end == None:
+            end = date.today()
+        else:
+            end = self.end
+
+        duration = end - self.start
+
+        return duration.days
+
+# Unsure about this class; is it too generic for our data?
+
+class Procedure:
+
+    def __init__(self, data):
+        # Can be a foreign key on charge list,
+        # enabling us to capture procedure cost data
+        self.name = data["name"]
+
+
+# Medical facility class:
+class Facility:
+
+    def __init__(self, data):
+        # Unique facility ID:
+        self.id = data["id"]
+        self.name = data["name"]
+        self.state = data["state"]
+        self.city = data["city"]
+        self.address = data["address"]
+        # For instance "hospital", "out-patient clinic", etc.
+        self.type = data["type"]
+
+# Healthcare provider class:
+class Provider:
+
+    def __init__(self, data):
+        # Unique physician ID:
+        self.id = data["id"]
+        # Primary facility for physician, foreign key on Facility objects
+        self.facility_id = data["facility_id"]
+        self.first_name = data["first_name"]
+        self.last_name = data["last_name"]
+        # Provider type: RN, EMT, MD, etc.
+        self.type = data["type"]
+        # Provider title:
+        self.title = data["title"]