💫 Add Language.pipe_labels (#4276)

* Add Language.pipe_labels

* Update spacy/language.py

Co-Authored-By: Matthew Honnibal <honnibal+gh@gmail.com>

spacy/language.py

@@ -248,6 +248,18 @@ class Language(object):
         """
         return [pipe_name for pipe_name, _ in self.pipeline]
 
+    @property
+    def pipe_labels(self):
+        """Get the labels set by the pipeline components, if available.
+
+        RETURNS (dict): Labels keyed by component name.
+        """
+        labels = OrderedDict()
+        for name, pipe in self.pipeline:
+            if hasattr(pipe, "labels"):
+                labels[name] = list(pipe.labels)
+        return labels
+
     def get_pipe(self, name):
         """Get a pipeline component for a given component name.
 

spacy/tests/pipeline/test_pipe_methods.py

@@ -128,3 +128,19 @@ def test_pipe_base_class_add_label(nlp, component):
         assert label in pipe.labels
     else:
         assert pipe.labels == (label,)
+
+
+def test_pipe_labels(nlp):
+    input_labels = {
+        "ner": ["PERSON", "ORG", "GPE"],
+        "textcat": ["POSITIVE", "NEGATIVE"],
+    }
+    for name, labels in input_labels.items():
+        pipe = nlp.create_pipe(name)
+        for label in labels:
+            pipe.add_label(label)
+        assert len(pipe.labels) == len(labels)
+        nlp.add_pipe(pipe)
+    assert len(nlp.pipe_labels) == len(input_labels)
+    for name, labels in nlp.pipe_labels.items():
+        assert sorted(input_labels[name]) == sorted(labels)