fix numpy array handling in strings to addresses (#333)

Author: kevinsung

python/ffsim/states/bitstring.py

@@ -462,7 +462,7 @@ def strings_to_addresses(
     """
     if not len(strings):
         return np.array([])
-    if isinstance(strings, np.ndarray):
+    if isinstance(strings, np.ndarray) and strings.ndim == 2:
         bitstring_type = BitstringType.BIT_ARRAY
     elif isinstance(strings[0], str):
         bitstring_type = BitstringType.STRING

tests/python/states/bitstring_test.py

@@ -549,17 +549,19 @@ def test_strings_to_addresses_int():
     nelec = (2, 1)
     dim = ffsim.dim(norb, nelec)
     indices = ffsim.strings_to_addresses(
-        [
-            0b001011,
-            0b010011,
-            0b100011,
-            0b001101,
-            0b010101,
-            0b100101,
-            0b001110,
-            0b010110,
-            0b100110,
-        ],
+        np.array(
+            [
+                0b001011,
+                0b010011,
+                0b100011,
+                0b001101,
+                0b010101,
+                0b100101,
+                0b001110,
+                0b010110,
+                0b100110,
+            ]
+        ),
         norb,
         nelec,
     )