Close LAA loophole

bio2zarr/vcf2zarr/vcz.py

@@ -525,14 +525,17 @@ def compute_laa_field(genotypes) -> np.ndarray:
     if np.any(genotypes >= v):
         raise ValueError("Extreme allele value not supported")
     G = genotypes.astype(np.int32)
-    # Anything <=0 gets mapped to -2 (pad) in the output, which comes last.
-    # So, to get this sorting correctly, we remap to the largest value for
-    # sorting, then map back. We promote the genotypes up to 32 bit for convenience
-    # here, assuming that we'll never have a allele of 2**31 - 1.
-    assert np.all(G != v)
-    G[G <= 0] = v
-    G.sort(axis=1)
-    G[G == v] = -2
+    if len(G) > 0:
+        # Anything <=0 gets mapped to -2 (pad) in the output, which comes last.
+        # So, to get this sorting correctly, we remap to the largest value for
+        # sorting, then map back. We promote the genotypes up to 32 bit for convenience
+        # here, assuming that we'll never have a allele of 2**31 - 1.
+        assert np.all(G != v)
+        G[G <= 0] = v
+        G.sort(axis=1)
+        # Equal non-zero values result in padding also
+        G[G[:, 0] == G[:, 1], 1] = -2
+        G[G == v] = -2
     return G.astype(genotypes.dtype)
 
 

tests/test_local_alleles.py

@@ -9,9 +9,10 @@ class TestComputeLAA:
     @pytest.mark.parametrize(
         ("genotypes", "expected"),
         [
-            ([[]], [[]]),
+            ([], []),
             ([[0, 0]], [[-2, -2]]),
             ([[0, 0], [0, 0]], [[-2, -2], [-2, -2]]),
+            ([[1, 1], [0, 0]], [[1, -2], [-2, -2]]),
             ([[0, 1], [3, 2], [3, 0]], [[1, -2], [2, 3], [3, -2]]),
             ([[0, 0], [2, 3]], [[-2, -2], [2, 3]]),
             ([[2, 3], [0, 0]], [[2, 3], [-2, -2]]),