Add helper functions

analysis/pf_variables_library.py

@@ -0,0 +1,22 @@
+# Function to check status of a condition within a specified time window
+def check_pregnancy_status(index_date, selected_events, codelist):
+    return (
+        selected_events.where(selected_events.snomedct_code.is_in(codelist))
+        .where(
+            selected_events.date.is_on_or_between(index_date - months(1), index_date)
+        )
+        .exists_for_patient()
+    )
+
+
+# Function to count number of coded events within a specified time window
+def count_past_events(index_date, selected_events, codelist, num_months):
+    return (
+        selected_events.where(selected_events.snomedct_code.is_in(codelist))
+        .where(
+            selected_events.date.is_on_or_between(
+                index_date - months(num_months), index_date
+            )
+        )
+        .count_for_patient()
+    )