Handle some awkward corner cases

CHANGELOG.md

@@ -1,5 +1,7 @@
 # 0.1.2 2024-XX-XX
 
+- Reduce memory requirement for encoding genotypes with large sample sizes
+
 - Transpose default chunk sizes to 1000 variants and 10,000 samples (issue:300)
 
 - Add chunksize options to mkschema (issue:294)

bio2zarr/vcf2zarr/vcz.py

@@ -382,7 +382,7 @@ def fixed_field_spec(
                 continue
             array_specs.append(spec_from_field(field))
 
-        if gt_field is not None:
+        if gt_field is not None and n > 0:
             ploidy = max(gt_field.summary.max_number - 1, 1)
             shape = [m, n]
             chunks = [variants_chunk_size, samples_chunk_size]
@@ -832,6 +832,7 @@ def encode_partition(self, partition_index):
                 self.encode_array_partition(array_spec, partition_index)
         if self.has_genotypes():
             self.encode_genotypes_partition(partition_index)
+            self.encode_genotype_mask_partition(partition_index)
         if self.has_local_alleles():
             self.encode_local_alleles_partition(partition_index)
             self.encode_local_allele_fields_partition(partition_index)
@@ -899,8 +900,10 @@ def encode_genotypes_partition(self, partition_index):
         self.finalise_partition_array(partition_index, gt)
         self.finalise_partition_array(partition_index, gt_phased)
 
-        # Read back in the genotypes so we can compute the mask
+    def encode_genotype_mask_partition(self, partition_index):
+        partition = self.metadata.partitions[partition_index]
         gt_mask = self.init_partition_array(partition_index, "call_genotype_mask")
+        # Read back in the genotypes so we can compute the mask
         gt_array = zarr.open_array(
             store=self.wip_partition_array_path(partition_index, "call_genotype"),
             mode="r",

tests/test_icf.py

@@ -91,6 +91,19 @@ def test_INFO_NS(self, icf):
         assert icf["INFO/NS"].values == [None, None, 3, 3, 2, 3, 3, None, None]
 
 
+class TestWithGtHeaderNoGenotypes:
+    data_path = "tests/data/vcf/sample_no_genotypes_with_gt_header.vcf.gz"
+
+    @pytest.fixture(scope="class")
+    def icf(self, tmp_path_factory):
+        out = tmp_path_factory.mktemp("data") / "example.exploded"
+        return vcf2zarr.explode(out, [self.data_path])
+
+    def test_gts(self, icf):
+        values = icf["FORMAT/GT"].values
+        assert values == [None] * icf.num_records
+
+
 class TestIcfWriterExample:
     data_path = "tests/data/vcf/sample.vcf.gz"
 

tests/test_vcf_examples.py

@@ -508,6 +508,19 @@ def test_ok_without_local_alleles(self, ds):
         nt.assert_array_equal(ds.call_genotype.values, [[[0, 0, 0]]])
 
 
+class TestWithGtHeaderNoGenotypes:
+    data_path = "tests/data/vcf/sample_no_genotypes_with_gt_header.vcf.gz"
+
+    @pytest.fixture(scope="class")
+    def ds(self, tmp_path_factory):
+        out = tmp_path_factory.mktemp("data") / "example.vcf.zarr"
+        vcf2zarr.convert([self.data_path], out, worker_processes=0)
+        return sg.load_dataset(out)
+
+    def test_gts(self, ds):
+        assert "call_genotype" not in ds
+
+
 class Test1000G2020Example:
     data_path = "tests/data/vcf/1kg_2020_chrM.vcf.gz"