Sanitize strand to use int8 dtype and update checks (#60)

Also fixes issues for window functions where strand is None.

src/genomicranges/GenomicRanges.py

@@ -2532,7 +2532,7 @@ def tile_by_range(
             )
 
             seqnames.extend([val.seqnames[0]] * len(all_intervals))
-            strand.extend([val.strand[0]] * len(all_intervals))
+            strand.extend([int(val.strand[0])] * len(all_intervals))
             starts.extend([x[0] for x in all_intervals])
             widths.extend(x[1] for x in all_intervals)
 
@@ -2594,7 +2594,7 @@ def tile(
             )
 
             seqnames.extend([val.seqnames[0]] * len(all_intervals))
-            strand.extend([val.strand[0]] * len(all_intervals))
+            strand.extend([int(val.strand[0])] * len(all_intervals))
             starts.extend([x[0] for x in all_intervals])
             widths.extend(x[1] for x in all_intervals)
 
@@ -2636,7 +2636,7 @@ def sliding_windows(self, width: int, step: int = 1) -> "GenomicRanges":
             )
 
             seqnames.extend([val.seqnames[0]] * len(all_intervals))
-            strand.extend([val.strand[0]] * len(all_intervals))
+            strand.extend([int(val.strand[0])] * len(all_intervals))
             starts.extend([x[0] for x in all_intervals])
             widths.extend(x[1] for x in all_intervals)
 

src/genomicranges/utils.py

@@ -1,4 +1,4 @@
-from typing import List, Sequence, Union, Optional, Tuple
+from typing import List, Optional, Sequence, Tuple, Union
 
 import biocutils as ut
 import numpy as np
@@ -41,18 +41,23 @@ def sanitize_strand_vector(
             raise ValueError(
                 "'strand' must only contain values 1 (forward strand), -1 (reverse strand) or 0 (reverse strand)."
             )
-        return strand
+        return strand.astype(np.int8)
 
     if ut.is_list_of_type(strand, str):
         if not set(strand).issubset(["+", "-", "*"]):
             raise ValueError("Values in 'strand' must be either +, - or *.")
-        return np.array([STRAND_MAP[x] for x in strand])
-    elif ut.is_list_of_type(strand, int):
-        return np.array(strand)
-    else:
-        TypeError(
-            "'strand' must be either a numpy vector, a list of integers or strings representing strand."
-        )
+        return np.array([STRAND_MAP[x] for x in strand], dtype=np.int8)
+
+    if ut.is_list_of_type(strand, (int, float, np.int_)):
+        if not set(strand).issubset([1, 0, -1]):
+            raise ValueError(
+                "'strand' must only contain values 1 (forward strand), -1 (reverse strand) or 0 (reverse strand)."
+            )
+        return np.array(strand, dtype=np.int8)
+
+    raise TypeError(
+        "'strand' must be either a numpy vector, a list of integers or strings representing strand."
+    )
 
 
 def _sanitize_strand_search_ops(query_strand, subject_strand):