Correct char label between entities

bio_parser/parse/document.py

@@ -315,7 +315,7 @@ class Document:
     def char_labels(self) -> list[str]:
         r"""Character-level IOB labels.
 
-        Spaces between two tokens with the same label get the same label, others get 'O'.
+        Spaces between two tokens part of the same entities with the same label get the same label, others get 'O'.
 
         Examples:
             The space between 'I' and 'run' is tagged as 'I-Animal', because it's the same named entity label.
@@ -325,12 +325,18 @@ class Document:
             The space between 'run' and 'fast' is tagged as 'O', because it's not the same label.
             >>> Document(bio_repr="run B-Animal\nfast O").char_labels
             ['B-Animal', 'I-Animal', 'I-Animal', 'O', 'O', 'O', 'O', 'O']
+
+            The space between 'dog' and 'cat' is tagged as 'O', because it's not the same entity.
+            >>> Document(bio_repr="run B-Animal\ncat B-Animal").char_labels
+            ['B-Animal', 'I-Animal', 'I-Animal', 'O', 'B-Animal', 'I-Animal', 'I-Animal']
         """
         tags = []
         for token, next_token in pairwise(self.tokens + [None]):
             # Add token tags
             tags.extend(token.labels)
-            if next_token and token.label == next_token.label:
+            if next_token and (
+                token.label == next_token.label and not next_token.tag == Tag.BEGINNING
+            ):
                 tags.append(next_token.iob_label)
             elif next_token:
                 tags.append(Tag.OUTSIDE.value)

tests/parse/test_document.py

@@ -189,6 +189,25 @@ def test_parse_token(document: Document):
     assert token.chars == ["r", "o", "b", "o", "t", "s"]
 
 
+def test_consecutive_entities():
+    # BIO FILE
+    # dog B-Animal
+    # cat B-Animal
+    document = Document("dog B-Animal\ncat B-Animal")
+
+    assert document.chars == ["d", "o", "g", " ", "c", "a", "t"]
+
+    assert document.char_labels == [
+        "B-Animal",
+        "I-Animal",
+        "I-Animal",
+        "O",  # Character between two new entities should be set to O
+        "B-Animal",
+        "I-Animal",
+        "I-Animal",
+    ]
+
+
 @pytest.mark.parametrize(
     "annotation",
     ["Something something", "Something A-GPE", "Something GPE-A", "Something A"],