Update schema.py

src/meds/schema.py

@@ -21,14 +21,11 @@
 birth_code = "SNOMED/184099003"
 death_code = "SNOMED/419620001"
 
-# We define static events as always occurring on January 1st, 1 AD
-static_event_time = datetime.datetime(1, 1, 1)
-
 def patient_schema(per_event_properties_schema=pa.null()):
     # Return a patient schema with a particular per event metadata subschema
     event = pa.struct(
         [
-            pa.field("time", pa.timestamp("us"), nullable=False),
+            pa.field("time", pa.timestamp("us")), # Static events will have a null timestamp
             pa.field("code", pa.string(), nullable=False),
             pa.field("text_value", pa.string()),
             pa.field("numeric_value", pa.float32()),
@@ -40,7 +37,7 @@ def patient_schema(per_event_properties_schema=pa.null()):
     patient = pa.schema(
         [
             pa.field("patient_id", pa.int64(), nullable=False),
-            pa.field("events", pa.list_(event), nullable=False),  # Require ordered by time
+            pa.field("events", pa.list_(event), nullable=False),  # Require ordered by time, nulls must be first
         ]
     )