[#174] Do some minor refactoring and cleanup of linking.core.threshold

hlink/linking/core/threshold.py

@@ -81,7 +81,7 @@ def predict_using_thresholds(
 def _apply_alpha_threshold(pred_df: DataFrame, alpha_threshold: float) -> DataFrame:
     return pred_df.selectExpr(
         "*",
-        f"case when probability >= {alpha_threshold} then 1 else 0 end as prediction",
+        f"CASE WHEN probability >= {alpha_threshold} THEN 1 ELSE 0 END AS prediction",
     )
 
 
@@ -95,39 +95,39 @@ def _apply_threshold_ratio(
         raise NameError(
             'In order to calculate the threshold ratio based on probabilities, you need to have a "probability" column in your data.'
         )
-    else:
-        windowSpec = Window.partitionBy(df[f"{id_a}"]).orderBy(
-            df["probability"].desc(), df[f"{id_b}"]
+
+    windowSpec = Window.partitionBy(df[id_a]).orderBy(
+        df["probability"].desc(), df[id_b]
+    )
+    prob_rank = rank().over(windowSpec)
+    prob_lead = lead(df["probability"], 1).over(windowSpec)
+    return (
+        df.select(
+            df["*"],
+            prob_rank.alias("prob_rank"),
+            prob_lead.alias("second_best_prob"),
         )
-        prob_rank = rank().over(windowSpec)
-        prob_lead = lead(df["probability"], 1).over(windowSpec)
-        return (
-            df.select(
-                df["*"],
-                prob_rank.alias("prob_rank"),
-                prob_lead.alias("second_best_prob"),
-            )
-            .selectExpr(
-                "*",
-                f"""
-            IF(
-              second_best_prob IS NOT NULL
-              AND second_best_prob >= {alpha_threshold}
-              AND prob_rank == 1,
-              probability / second_best_prob,
-              NULL)
-            as ratio
-            """,
-            )
-            .selectExpr(
-                "*",
-                f"""
-            CAST(
-                probability >= {alpha_threshold}
-            AND prob_rank == 1
-            AND (ratio > {threshold_ratio} OR ratio is NULL)
-            as INT) as prediction
-            """,
-            )
-            .drop("prob_rank")
+        .selectExpr(
+            "*",
+            f"""
+        IF(
+          second_best_prob IS NOT NULL
+          AND second_best_prob >= {alpha_threshold}
+          AND prob_rank == 1,
+          probability / second_best_prob,
+          NULL)
+        AS ratio
+        """,
         )
+        .selectExpr(
+            "*",
+            f"""
+        CAST(
+            probability >= {alpha_threshold}
+        AND prob_rank == 1
+        AND (ratio > {threshold_ratio} OR ratio IS NULL)
+        AS INT) AS prediction
+        """,
+        )
+        .drop("prob_rank")
+    )