fix(study_locus_valiation): ensure the the transQtlColumn is missing

src/gentropy/dataset/study_locus.py

@@ -433,7 +433,8 @@ def _qc_subsignificant_associations(
     def qc_abnormal_pips(
         self: StudyLocus,
         sum_pips_lower_threshold: float = 0.99,
-        sum_pips_upper_threshold: float = 1.0001,  # Set slightly above 1 to account for floating point errors
+        # Set slightly above 1 to account for floating point errors
+        sum_pips_upper_threshold: float = 1.0001,
     ) -> StudyLocus:
         """Filter study-locus by sum of posterior inclusion probabilities to ensure that the sum of PIPs is within a given range.
 
@@ -691,6 +692,7 @@ def flag_trans_qtls(
         """Flagging transQTL credible sets based on genomic location of the measured gene.
 
         Process:
+        0. Make sure that the `isTransQtl` column does not exist (remove if exists)
         1. Enrich study-locus dataset with geneId based on study metadata. (only QTL studies are considered)
         2. Enrich with transcription start site and chromosome of the studied gegne.
         3. Flagging any tagging variant of QTL credible sets, if chromosome is different from the gene or distance is above the threshold.
@@ -709,6 +711,12 @@ def flag_trans_qtls(
         if "geneId" not in study_index.df.columns:
             return self
 
+        # We have to remove the column `isTransQtl` to ensure the column is not duplicated
+        # The duplication can happen when one reads the StudyLocus from parquet with
+        # predefined schema that already contains the `isTransQtl` column.
+        if "isTransQtl" in self.df.columns:
+            self.df = self.df.drop("isTransQtl")
+
         # Process study index:
         processed_studies = (
             study_index.df

tests/gentropy/dataset/test_study_locus.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+from pathlib import Path
 from typing import Any
 
 import pyspark.sql.functions as f
@@ -18,6 +19,8 @@
     StructType,
 )
 
+from gentropy.common.schemas import SchemaValidationError
+from gentropy.common.session import Session
 from gentropy.dataset.colocalisation import Colocalisation
 from gentropy.dataset.l2g_feature_matrix import L2GFeatureMatrix
 from gentropy.dataset.ld_index import LDIndex
@@ -1209,7 +1212,6 @@ class TestTransQtlFlagging:
     ]
 
     STUDY_LOCUS_COLUMNS = ["studyLocusId", "variantId", "studyId"]
-
     STUDY_DATA = [
         ("s1", "p1", "qtl", "g1"),
         ("s2", "p2", "gwas", None),
@@ -1221,21 +1223,21 @@ class TestTransQtlFlagging:
     GENE_COLUMNS = ["id", "strand", "start", "end", "chromosome", "tss"]
 
     @pytest.fixture(autouse=True)
-    def _setup(self: TestTransQtlFlagging, spark: SparkSession) -> None:
+    def _setup(self: TestTransQtlFlagging, session: Session) -> None:
         """Setup study locus for testing."""
         self.study_locus = StudyLocus(
             _df=(
-                spark.createDataFrame(
+                session.spark.createDataFrame(
                     self.STUDY_LOCUS_DATA, self.STUDY_LOCUS_COLUMNS
                 ).withColumn("locus", f.array(f.struct("variantId")))
             )
         )
         self.study_index = StudyIndex(
-            _df=spark.createDataFrame(self.STUDY_DATA, self.STUDY_COLUMNS)
+            _df=session.spark.createDataFrame(self.STUDY_DATA, self.STUDY_COLUMNS)
         )
         self.target_index = TargetIndex(
             _df=(
-                spark.createDataFrame(self.GENE_DATA, self.GENE_COLUMNS).select(
+                session.spark.createDataFrame(self.GENE_DATA, self.GENE_COLUMNS).select(
                     f.struct(
                         f.col("strand").cast(IntegerType()).alias("strand"),
                         "start",
@@ -1283,3 +1285,27 @@ def test_correctness_found_trans(self: TestTransQtlFlagging) -> None:
         assert (
             self.qtl_flagged.df.filter(f.col("isTransQtl")).count() == 2
         ), "Expected number of rows differ from observed."
+
+    def test_add_flag_if_column_is_present(
+        self: TestTransQtlFlagging, tmp_path: Path, session: Session
+    ) -> None:
+        """Test adding flag if the `isTransQtl` column is already present.
+
+        When reading the dataset, the reader will add the `isTransQtl` column to
+        the schema, which can cause column duplication captured only by Dataset schema validation.
+
+        This test ensures that the column is dropped before the `flag_trans_qtls` is run.
+        """
+        dataset_path = str(tmp_path / "study_locus")
+        self.study_locus.df.write.parquet(dataset_path)
+        schema_validated_study_locus = StudyLocus.from_parquet(session, dataset_path)
+        assert (
+            "isTransQtl" in schema_validated_study_locus.df.columns
+        ), "`isTransQtl` column is missing after reading the dataset."
+        # Rerun the flag addition and check if any error is raised by the schema validation
+        try:
+            schema_validated_study_locus.flag_trans_qtls(
+                self.study_index, self.target_index, self.THRESHOLD
+            )
+        except SchemaValidationError:
+            pytest.fail("Failed to validate the schema when adding isTransQtl flag")