[Python] (scalar) vector reading speedup via numpy (#4390)

* Add numpy accessor to python flatbuffers scalar vectors

* Update python tests to test numpy vector accessor

* Update appveyor CI to run Python tests, save generated code as artifact

* Update example generated python code

* Add numpy info to python usage docs

* Update test schema and python tests w/ multi-byte vector

* did not mean to push profiling code

* adding float64 numpy tests

tests/py_test.py

@@ -15,6 +15,7 @@
 
 import os.path
 import sys
+import imp
 PY_VERSION = sys.version_info[:2]
 
 import ctypes
@@ -25,6 +26,7 @@ import unittest
 
 from flatbuffers import compat
 from flatbuffers.compat import range_func as compat_range
+from flatbuffers.compat import NumpyRequiredForThisFeature
 
 import flatbuffers
 from flatbuffers import number_types as N
@@ -130,6 +132,40 @@ def CheckReadBuffer(buf, offset):
         invsum += int(v)
     asserter(invsum == 10)
 
+    for i in range(5):
+        asserter(monster.VectorOfLongs(i) == 10 ** (i * 2))
+
+    asserter(([-1.7976931348623157e+308, 0, 1.7976931348623157e+308]
+              == [monster.VectorOfDoubles(i)
+                  for i in range(monster.VectorOfDoublesLength())]))
+
+    try:
+        imp.find_module('numpy')
+        # if numpy exists, then we should be able to get the
+        # vector as a numpy array
+        import numpy as np
+
+        asserter(monster.InventoryAsNumpy().sum() == 10)
+        asserter(monster.InventoryAsNumpy().dtype == np.dtype('uint8'))
+
+        VectorOfLongs = monster.VectorOfLongsAsNumpy()
+        asserter(VectorOfLongs.dtype == np.dtype('int64'))
+        for i in range(5):
+            asserter(VectorOfLongs[i] == 10 ** (i * 2))
+
+        VectorOfDoubles = monster.VectorOfDoublesAsNumpy()
+        asserter(VectorOfDoubles.dtype == np.dtype('float64'))
+        asserter(VectorOfDoubles[0] == np.finfo('float64').min)
+        asserter(VectorOfDoubles[1] == 0.0)
+        asserter(VectorOfDoubles[2] == np.finfo('float64').max)
+
+    except ImportError:
+        # If numpy does not exist, trying to get vector as numpy
+        # array should raise NumpyRequiredForThisFeature. The way
+        # assertRaises has been implemented prevents us from
+        # asserting this error is raised outside of a test case.
+        pass
+
     asserter(monster.Test4Length() == 2)
 
     # create a 'Test' object and populate it:
@@ -794,6 +830,20 @@ def make_monster_from_generated_code():
     b.PrependUOffsetTRelative(test1)
     testArrayOfString = b.EndVector(2)
 
+    MyGame.Example.Monster.MonsterStartVectorOfLongsVector(b, 5)
+    b.PrependInt64(100000000)
+    b.PrependInt64(1000000)
+    b.PrependInt64(10000)
+    b.PrependInt64(100)
+    b.PrependInt64(1)
+    VectorOfLongs = b.EndVector(5)
+
+    MyGame.Example.Monster.MonsterStartVectorOfDoublesVector(b, 3)
+    b.PrependFloat64(1.7976931348623157e+308)
+    b.PrependFloat64(0)
+    b.PrependFloat64(-1.7976931348623157e+308)
+    VectorOfDoubles = b.EndVector(3)
+
     MyGame.Example.Monster.MonsterStart(b)
 
     pos = MyGame.Example.Vec3.CreateVec3(b, 1.0, 2.0, 3.0, 3.0, 2, 5, 6)
@@ -806,6 +856,8 @@ def make_monster_from_generated_code():
     MyGame.Example.Monster.MonsterAddTest(b, mon2)
     MyGame.Example.Monster.MonsterAddTest4(b, test4)
     MyGame.Example.Monster.MonsterAddTestarrayofstring(b, testArrayOfString)
+    MyGame.Example.Monster.MonsterAddVectorOfLongs(b, VectorOfLongs)
+    MyGame.Example.Monster.MonsterAddVectorOfDoubles(b, VectorOfDoubles)
     mon = MyGame.Example.Monster.MonsterEnd(b)
 
     b.Finish(mon)
@@ -962,6 +1014,15 @@ class TestAllCodePathsOfExampleSchema(unittest.TestCase):
         self.assertEqual(0, mon2.Testnestedflatbuffer(0))
         self.assertEqual(2, mon2.Testnestedflatbuffer(1))
         self.assertEqual(4, mon2.Testnestedflatbuffer(2))
+        try:
+            imp.find_module('numpy')
+            # if numpy exists, then we should be able to get the
+            # vector as a numpy array
+            self.assertEqual([0, 2, 4], mon2.TestnestedflatbufferAsNumpy().tolist())
+        except ImportError:
+            assertRaises(self,
+                         lambda: mon2.TestnestedflatbufferAsNumpy(),
+                         NumpyRequiredForThisFeature)
 
     def test_nondefault_monster_testempty(self):
         b = flatbuffers.Builder(0)