add references for join_types

csst_dag/dag/dispatcher.py

@@ -8,7 +8,6 @@ from .._csst import csst
 
 # from csst_dag._csst import csst
 
-
 # THESE ARE GENERAL PARAMETERS!
 PLAN_PARAMS = {
     "dataset": None,
@@ -50,6 +49,44 @@ PROC_PARAMS = {
     # should be capable to extend
 }
 
+# plan basis keys
+PLAN_BASIS_KEYS = (
+    "dataset",
+    "instrument",
+    "obs_type",
+    "obs_group",
+    "obs_id",
+    "n_frame",
+    "_id",
+)
+
+# data basis keys
+DATA_BASIS_KEYS = (
+    "dataset",
+    "instrument",
+    "obs_type",
+    "obs_group",
+    "obs_id",
+    "detector",
+    "file_name",
+    "_id",
+)
+
+# join_type for data x plan
+PLAN_JOIN_TYPE = "inner"
+"""
+References:
+    - https://docs.astropy.org/en/stable/api/astropy.table.join.html
+    - https://docs.astropy.org/en/stable/table/operations.html#join
+
+Typical types:
+    - inner join: Only matching rows from both tables
+    - left join: All rows from left table, matching rows from right table
+    - right join: All rows from right table, matching rows from left table
+    - outer join: All rows from both tables
+    - cartesian join: Every combination of rows from both tables
+"""
+
 
 def override_common_keys(d1: dict, d2: dict) -> dict:
     """
@@ -105,33 +142,6 @@ def split_data_basis(data_basis: table.Table, n_split: int = 1) -> list[table.Ta
     return chunks
 
 
-# plan basis keys
-PLAN_BASIS_KEYS = (
-    "dataset",
-    "instrument",
-    "obs_type",
-    "obs_group",
-    "obs_id",
-    "n_frame",
-    "_id",
-)
-
-# data basis keys
-DATA_BASIS_KEYS = (
-    "dataset",
-    "instrument",
-    "obs_type",
-    "obs_group",
-    "obs_id",
-    "detector",
-    "file_name",
-    "_id",
-)
-
-# join_type for data x plan
-PLAN_JOIN_TYPE = "inner"
-
-
 class Dispatcher:
     """
     A class to dispatch tasks based on the observation type.