Add support for index -s/--stats

tests/test_bcftools_validation.py

@@ -74,6 +74,8 @@ def test_vcf_output(tmp_path, args, vcf_file):
     [
         ("index -n", "sample.vcf.gz"),
         ("index --nrecords", "1kg_2020_chrM.vcf.gz"),
+        ("index -s", "sample.vcf.gz"),
+        ("index --stats", "1kg_2020_chrM.vcf.gz"),
         ("query -l", "sample.vcf.gz"),
         ("query --list-samples", "1kg_2020_chrM.vcf.gz"),
     ],

tests/test_stats.py

@@ -1,7 +1,7 @@
 import pathlib
 from io import StringIO
 
-from vcztools.stats import nrecords
+from vcztools.stats import nrecords, stats
 
 from .utils import vcz_path_cache
 
@@ -13,3 +13,19 @@ def test_nrecords():
     output_str = StringIO()
     nrecords(vcz, output_str)
     assert output_str.getvalue() == "9\n"
+
+
+def test_stats():
+    original = pathlib.Path("tests/data/vcf") / "sample.vcf.gz"
+    vcz = vcz_path_cache(original)
+
+    output_str = StringIO()
+    stats(vcz, output_str)
+
+    assert (
+        output_str.getvalue()
+        == """19	.	2
+20	.	6
+X	.	1
+"""
+    )

vcztools/cli.py

@@ -3,7 +3,8 @@
 import click
 
 from . import query as query_module
-from . import regions, stats, vcf_writer
+from . import regions, vcf_writer
+from . import stats as stats_module
 
 
 class NaturalOrderGroup(click.Group):
@@ -23,9 +24,17 @@ def list_commands(self, ctx):
     is_flag=True,
     help="Print the number of records (variants).",
 )
-def index(path, nrecords):
+@click.option(
+    "-s",
+    "--stats",
+    is_flag=True,
+    help="Print per contig stats.",
+)
+def index(path, nrecords, stats):
     if nrecords:
-        stats.nrecords(path, sys.stdout)
+        stats_module.nrecords(path, sys.stdout)
+    elif stats:
+        stats_module.stats(path, sys.stdout)
     else:
         regions.create_index(path)
 

vcztools/stats.py

@@ -1,3 +1,4 @@
+import numpy as np
 import zarr
 
 from vcztools.utils import open_file_like
@@ -9,3 +10,29 @@ def nrecords(vcz, output):
     with open_file_like(output) as output:
         num_variants = root["variant_position"].shape[0]
         print(num_variants, file=output)
+
+
+def stats(vcz, output):
+    root = zarr.open(vcz, mode="r")
+
+    with open_file_like(output) as output:
+        contigs = root["contig_id"][:].astype("U").tolist()
+        if "contig_length" in root:
+            contig_lengths = root["contig_length"][:]
+        else:
+            contig_lengths = ["."] * len(contigs)
+
+        region_index = root["region_index"][:]
+
+        contig_indexes = region_index[:, 1]
+        num_records = region_index[:, 5]
+
+        num_records_per_contig = np.bincount(
+            contig_indexes, weights=num_records
+        ).astype(np.int64)
+
+        for contig, contig_length, nr in zip(
+            contigs, contig_lengths, num_records_per_contig
+        ):
+            if nr > 0:
+                print(f"{contig}\t{contig_length}\t{nr}", file=output)