From 72889a16d558848191e51f4bfb200e70d3bc413a Mon Sep 17 00:00:00 2001
From: Matthew Honnibal <honnibal+gh@gmail.com>
Date: Wed, 20 Mar 2019 12:09:59 +0100
Subject: [PATCH] Fix similarity calculation if vectors are on GPU (#3440)

---
 spacy/tokens/doc.pyx   |  7 ++++---
 spacy/tokens/span.pyx  | 10 ++++------
 spacy/tokens/token.pyx |  4 +++-
 3 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/spacy/tokens/doc.pyx b/spacy/tokens/doc.pyx
index dd610bd6d..d4d7e5fa4 100644
--- a/spacy/tokens/doc.pyx
+++ b/spacy/tokens/doc.pyx
@@ -416,8 +416,9 @@ cdef class Doc:
                 return self.user_hooks["vector"](self)
             if self._vector is not None:
                 return self._vector
-            elif not len(self):
-                self._vector = numpy.zeros((self.vocab.vectors_length,), dtype="f")
+            xp = get_array_module(self.vocab.vectors.data)
+            if not len(self):
+                self._vector = xp.zeros((self.vocab.vectors_length,), dtype="f")
                 return self._vector
             elif self.vocab.vectors.data.size > 0:
                 self._vector = sum(t.vector for t in self) / len(self)
@@ -426,7 +427,7 @@ cdef class Doc:
                 self._vector = self.tensor.mean(axis=0)
                 return self._vector
             else:
-                return numpy.zeros((self.vocab.vectors_length,), dtype="float32")
+                return xp.zeros((self.vocab.vectors_length,), dtype="float32")
 
         def __set__(self, value):
             self._vector = value
diff --git a/spacy/tokens/span.pyx b/spacy/tokens/span.pyx
index 36eaeb568..e62caed40 100644
--- a/spacy/tokens/span.pyx
+++ b/spacy/tokens/span.pyx
@@ -420,13 +420,11 @@ cdef class Span:
         """
         if "vector_norm" in self.doc.user_span_hooks:
             return self.doc.user_span_hooks["vector"](self)
-        cdef float value
-        cdef double norm = 0
+        vector = self.vector
+        xp = get_array_module(vector)
         if self._vector_norm is None:
-            norm = 0
-            for value in self.vector:
-                norm += value * value
-            self._vector_norm = sqrt(norm) if norm != 0 else 0
+            total = (vector*vector).sum()
+            self._vector_norm = xp.sqrt(total) if total != 0. else 0.
         return self._vector_norm
 
     @property
diff --git a/spacy/tokens/token.pyx b/spacy/tokens/token.pyx
index 409b68290..66728d35c 100644
--- a/spacy/tokens/token.pyx
+++ b/spacy/tokens/token.pyx
@@ -404,7 +404,9 @@ cdef class Token:
         if "vector_norm" in self.doc.user_token_hooks:
             return self.doc.user_token_hooks["vector_norm"](self)
         vector = self.vector
-        return numpy.sqrt((vector ** 2).sum())
+        xp = get_array_module(vector)
+        total = (vector ** 2).sum()
+        return xp.sqrt(total) if total != 0. else 0.
 
     @property
     def n_lefts(self):