From e3af19a076104052f5ee0401868eb670346bd410 Mon Sep 17 00:00:00 2001
From: mpuels <mpuels@gmail.com>
Date: Wed, 6 Dec 2017 20:08:42 +0100
Subject: [PATCH] doc: Replace 'is not' with '!=' in code example

The function `dependency_labels_to_root(token)` defined in section *Get syntactic dependencies* does not terminate. Here is a complete example:

    import spacy

    nlp = spacy.load('en')
    doc = nlp("Apple and banana are similar. Pasta and hippo aren't.")

    def dependency_labels_to_root(token):
        """Walk up the syntactic tree, collecting the arc labels."""
        dep_labels = []
        while token.head is not token:
            dep_labels.append(token.dep)
            token = token.head
        return dep_labels

    dep_labels = dependency_labels_to_root(doc[1])
    dep_labels

Replacing `is not` with `!=` solves the issue:

    import spacy

    nlp = spacy.load('en')
    doc = nlp("Apple and banana are similar. Pasta and hippo aren't.")

    def dependency_labels_to_root(token):
        """Walk up the syntactic tree, collecting the arc labels."""
        dep_labels = []
        while token.head != token:
            dep_labels.append(token.dep)
            token = token.head
        return dep_labels

    dep_labels = dependency_labels_to_root(doc[1])
    dep_labels

The output is

    ['cc', 'nsubj']
---
 website/usage/_spacy-101/_lightning-tour.jade | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/website/usage/_spacy-101/_lightning-tour.jade b/website/usage/_spacy-101/_lightning-tour.jade
index 45c934319..96f274002 100644
--- a/website/usage/_spacy-101/_lightning-tour.jade
+++ b/website/usage/_spacy-101/_lightning-tour.jade
@@ -264,7 +264,7 @@ p
     def dependency_labels_to_root(token):
         """Walk up the syntactic tree, collecting the arc labels."""
         dep_labels = []
-        while token.head is not token:
+        while token.head != token:
             dep_labels.append(token.dep)
             token = token.head
         return dep_labels