From 1a05078c79d90e93333df6ccc72e0235b57fe159 Mon Sep 17 00:00:00 2001
From: ines <ines@ines.io>
Date: Wed, 17 May 2017 11:37:48 +0200
Subject: [PATCH] Add language-specific syntax iterators to en and de

---
 spacy/lang/de/__init__.py         |  2 ++
 spacy/lang/de/syntax_iterators.py | 38 +++++++++++++++++++++++++++
 spacy/lang/en/__init__.py         |  2 ++
 spacy/lang/en/syntax_iterators.py | 43 +++++++++++++++++++++++++++++++
 4 files changed, 85 insertions(+)
 create mode 100644 spacy/lang/de/syntax_iterators.py
 create mode 100644 spacy/lang/en/syntax_iterators.py

diff --git a/spacy/lang/de/__init__.py b/spacy/lang/de/__init__.py
index 2da572500..7a44b7485 100644
--- a/spacy/lang/de/__init__.py
+++ b/spacy/lang/de/__init__.py
@@ -5,6 +5,7 @@ from .tokenizer_exceptions import TOKENIZER_EXCEPTIONS
 from .tag_map import TAG_MAP
 from .stop_words import STOP_WORDS
 from .lemmatizer import LOOKUP
+from .syntax_iterators import SYNTAX_ITERATORS
 
 from ..tokenizer_exceptions import BASE_EXCEPTIONS
 from ...language import Language
@@ -23,6 +24,7 @@ class German(Language):
         tokenizer_exceptions = update_exc(BASE_EXCEPTIONS, TOKENIZER_EXCEPTIONS)
         tag_map = dict(TAG_MAP)
         stop_words = set(STOP_WORDS)
+        syntax_iterators = dict(SYNTAX_ITERATORS)
 
         @classmethod
         def create_lemmatizer(cls, nlp=None):
diff --git a/spacy/lang/de/syntax_iterators.py b/spacy/lang/de/syntax_iterators.py
new file mode 100644
index 000000000..ab750989e
--- /dev/null
+++ b/spacy/lang/de/syntax_iterators.py
@@ -0,0 +1,38 @@
+# coding: utf8
+from __future__ import unicode_literals
+
+from ...symbols import NOUN, PROPN, PRON
+
+
+def noun_chunks(obj):
+    """
+    Detect base noun phrases from a dependency parse. Works on both Doc and Span.
+    """
+    # this iterator extracts spans headed by NOUNs starting from the left-most
+    # syntactic dependent until the NOUN itself for close apposition and
+    # measurement construction, the span is sometimes extended to the right of
+    # the NOUN. Example: "eine Tasse Tee" (a cup (of) tea) returns "eine Tasse Tee"
+    # and not just "eine Tasse", same for "das Thema Familie".
+    labels = ['sb', 'oa', 'da', 'nk', 'mo', 'ag', 'ROOT', 'root', 'cj', 'pd', 'og', 'app']
+    doc = obj.doc # Ensure works on both Doc and Span.
+    np_label = doc.vocab.strings['NP']
+    np_deps = set(doc.vocab.strings[label] for label in labels)
+    close_app = doc.vocab.strings['nk']
+
+    rbracket = 0
+    for i, word in enumerate(obj):
+        if i < rbracket:
+            continue
+        if word.pos in (NOUN, PROPN, PRON) and word.dep in np_deps:
+            rbracket = word.i+1
+            # try to extend the span to the right
+            # to capture close apposition/measurement constructions
+            for rdep in doc[word.i].rights:
+                if rdep.pos in (NOUN, PROPN) and rdep.dep == close_app:
+                    rbracket = rdep.i+1
+            yield word.left_edge.i, rbracket, np_label
+
+
+SYNTAX_ITERATORS = {
+    'noun_chunks': noun_chunks
+}
diff --git a/spacy/lang/en/__init__.py b/spacy/lang/en/__init__.py
index 6430445a3..2d5314991 100644
--- a/spacy/lang/en/__init__.py
+++ b/spacy/lang/en/__init__.py
@@ -7,6 +7,7 @@ from .stop_words import STOP_WORDS
 from .lex_attrs import LEX_ATTRS
 from .morph_rules import MORPH_RULES
 from .lemmatizer import LEMMA_RULES, LEMMA_INDEX, LEMMA_EXC
+from .syntax_iterators import SYNTAX_ITERATORS
 
 from ..tokenizer_exceptions import BASE_EXCEPTIONS
 from ...language import Language
@@ -29,6 +30,7 @@ class English(Language):
         lemma_rules = dict(LEMMA_RULES)
         lemma_index = dict(LEMMA_INDEX)
         lemma_exc = dict(LEMMA_EXC)
+        sytax_iterators = dict(SYNTAX_ITERATORS)
 
 
 __all__ = ['English']
diff --git a/spacy/lang/en/syntax_iterators.py b/spacy/lang/en/syntax_iterators.py
new file mode 100644
index 000000000..dec240669
--- /dev/null
+++ b/spacy/lang/en/syntax_iterators.py
@@ -0,0 +1,43 @@
+# coding: utf8
+from __future__ import unicode_literals
+
+from ...symbols import NOUN, PROPN, PRON
+
+
+def noun_chunks(obj):
+    """
+    Detect base noun phrases from a dependency parse. Works on both Doc and Span.
+    """
+    labels = ['nsubj', 'dobj', 'nsubjpass', 'pcomp', 'pobj',
+              'attr', 'ROOT']
+    doc = obj.doc # Ensure works on both Doc and Span.
+    np_deps = [doc.vocab.strings[label] for label in labels]
+    conj = doc.vocab.strings['conj']
+    np_label = doc.vocab.strings['NP']
+    seen = set()
+    for i, word in enumerate(obj):
+        if word.pos not in (NOUN, PROPN, PRON):
+            continue
+        # Prevent nested chunks from being produced
+        if word.i in seen:
+            continue
+        if word.dep in np_deps:
+            if any(w.i in seen for w in word.subtree):
+                continue
+            seen.update(j for j in range(word.left_edge.i, word.i+1))
+            yield word.left_edge.i, word.i+1, np_label
+        elif word.dep == conj:
+            head = word.head
+            while head.dep == conj and head.head.i < head.i:
+                head = head.head
+            # If the head is an NP, and we're coordinated to it, we're an NP
+            if head.dep in np_deps:
+                if any(w.i in seen for w in word.subtree):
+                    continue
+                seen.update(j for j in range(word.left_edge.i, word.i+1))
+                yield word.left_edge.i, word.i+1, np_label
+
+
+SYNTAX_ITERATORS = {
+    'noun_chunks': noun_chunks
+}