Show warning if entity_ruler runs without patterns (#7807)

* Show warning if entity_ruler runs without patterns

* Show warning if matcher runs without patterns

* fix wording

* unit test for warning once (WIP)

* warn W036 only once

* cleanup

* create filter_warning helper

spacy/__init__.py

@@ -1,10 +1,10 @@
 from typing import Union, Iterable, Dict, Any
 from pathlib import Path
-import warnings
 import sys
 
-warnings.filterwarnings("ignore", message="numpy.dtype size changed")  # noqa
-warnings.filterwarnings("ignore", message="numpy.ufunc size changed")  # noqa
+# set library-specific custom warning handling before doing anything else
+from .errors import setup_default_warnings
+setup_default_warnings()
 
 # These are imported as part of the API
 from thinc.api import prefer_gpu, require_gpu, require_cpu  # noqa: F401

spacy/errors.py

@@ -1,3 +1,6 @@
+import warnings
+
+
 def add_codes(err_cls):
     """Add error codes to string messages via class attribute names."""
 
@@ -12,6 +15,30 @@ def add_codes(err_cls):
     return ErrorsWithCodes()
 
 
+def setup_default_warnings():
+    # ignore certain numpy warnings
+    filter_warning("ignore", error_msg="numpy.dtype size changed")  # noqa
+    filter_warning("ignore", error_msg="numpy.ufunc size changed")  # noqa
+
+    # warn about entity_ruler & matcher having no patterns only once
+    for pipe in ["matcher", "entity_ruler"]:
+        filter_warning("once", error_msg=Warnings.W036.format(name=pipe))
+
+
+def filter_warning(action: str, error_msg: str):
+    """Customize how spaCy should handle a certain warning.
+
+    error_msg (str): e.g. "W006", or a full error message
+    action (str): "default", "error", "ignore", "always", "module" or "once"
+    """
+    warnings.filterwarnings(action, message=_escape_warning_msg(error_msg))
+
+
+def _escape_warning_msg(msg):
+    """To filter with warnings.filterwarnings, the [] brackets need to be escaped"""
+    return msg.replace("[", "\\[").replace("]", "\\]")
+
+
 # fmt: off
 
 @add_codes
@@ -80,8 +107,9 @@ class Warnings:
             "@misc = \"spacy.LookupsDataLoader.v1\"\n"
             "lang = ${{nlp.lang}}\n"
             "tables = [\"lexeme_norm\"]\n")
-    W035 = ('Discarding subpattern "{pattern}" due to an unrecognized '
+    W035 = ("Discarding subpattern '{pattern}' due to an unrecognized "
             "attribute or operator.")
+    W036 = ("The component '{name}' does not have any patterns defined.")
 
     # New warnings added in v3.x
     W086 = ("Component '{listener}' will be (re)trained, but it needs the component "

spacy/matcher/matcher.pyx

@@ -138,6 +138,11 @@ cdef class Matcher:
         self._filter[key] = greedy
         self._patterns[key].extend(patterns)
 
+    def _require_patterns(self) -> None:
+        """Raise a warning if this component has no patterns defined."""
+        if len(self) == 0:
+            warnings.warn(Warnings.W036.format(name="matcher"))
+
     def remove(self, key):
         """Remove a rule from the matcher. A KeyError is raised if the key does
         not exist.
@@ -215,6 +220,7 @@ cdef class Matcher:
             If with_alignments is set to True and as_spans is set to False,
             A list of `(match_id, start, end, alignments)` tuples is returned.
         """
+        self._require_patterns()
         if isinstance(doclike, Doc):
             doc = doclike
             length = len(doc)

spacy/pipeline/entityruler.py

@@ -1,3 +1,4 @@
+import warnings
 from typing import Optional, Union, List, Dict, Tuple, Iterable, Any, Callable, Sequence
 from collections import defaultdict
 from pathlib import Path
@@ -6,7 +7,7 @@ import srsly
 from .pipe import Pipe
 from ..training import Example
 from ..language import Language
-from ..errors import Errors
+from ..errors import Errors, Warnings
 from ..util import ensure_path, to_disk, from_disk, SimpleFrozenList
 from ..tokens import Doc, Span
 from ..matcher import Matcher, PhraseMatcher
@@ -139,6 +140,7 @@ class EntityRuler(Pipe):
             error_handler(self.name, self, [doc], e)
 
     def match(self, doc: Doc):
+        self._require_patterns()
         matches = list(self.matcher(doc)) + list(self.phrase_matcher(doc))
         matches = set(
             [(m_id, start, end) for m_id, start, end in matches if start != end]
@@ -327,6 +329,11 @@ class EntityRuler(Pipe):
             self.nlp.vocab, attr=self.phrase_matcher_attr, validate=self._validate
         )
 
+    def _require_patterns(self) -> None:
+        """Raise a warning if this component has no patterns defined."""
+        if len(self) == 0:
+            warnings.warn(Warnings.W036.format(name=self.name))
+
     def _split_label(self, label: str) -> Tuple[str, str]:
         """Split Entity label into ent_label and ent_id if it contains self.ent_id_sep
 

spacy/tests/matcher/test_matcher_api.py

@@ -33,6 +33,15 @@ def test_matcher_from_api_docs(en_vocab):
     assert len(patterns[0])
 
 
+def test_matcher_empty_patterns_warns(en_vocab):
+    matcher = Matcher(en_vocab)
+    assert len(matcher) == 0
+    doc = Doc(en_vocab, words=["This", "is", "quite", "something"])
+    with pytest.warns(UserWarning):
+        matcher(doc)
+    assert len(doc.ents) == 0
+
+
 def test_matcher_from_usage_docs(en_vocab):
     text = "Wow 😀 This is really cool! 😂 😂"
     doc = Doc(en_vocab, words=text.split(" "))

spacy/tests/pipeline/test_entity_ruler.py

@@ -46,6 +46,17 @@ def test_entity_ruler_init(nlp, patterns):
     assert doc.ents[1].label_ == "BYE"
 
 
+def test_entity_ruler_no_patterns_warns(nlp):
+    ruler = EntityRuler(nlp)
+    assert len(ruler) == 0
+    assert len(ruler.labels) == 0
+    nlp.add_pipe("entity_ruler")
+    assert nlp.pipe_names == ["entity_ruler"]
+    with pytest.warns(UserWarning):
+        doc = nlp("hello world bye bye")
+    assert len(doc.ents) == 0
+
+
 def test_entity_ruler_init_patterns(nlp, patterns):
     # initialize with patterns
     ruler = nlp.add_pipe("entity_ruler")