Fixed type casting for Peewee aggregations [skip ci]

Author: ankane

README.md

@@ -496,7 +496,7 @@ Average vectors
 ```python
 from peewee import fn
 
-Item.select(fn.avg(Item.embedding)).scalar()
+Item.select(fn.avg(Item.embedding).coerce(True)).scalar()
 ```
 
 Also supports `sum`

tests/test_peewee.py

@@ -164,40 +164,36 @@ def test_where(self):
         assert [v.id for v in items] == [1]
 
     def test_vector_avg(self):
-        avg = Item.select(fn.avg(Item.embedding)).scalar()
+        avg = Item.select(fn.avg(Item.embedding).coerce(True)).scalar()
         assert avg is None
         Item.create(embedding=[1, 2, 3])
         Item.create(embedding=[4, 5, 6])
-        avg = Item.select(fn.avg(Item.embedding)).scalar()
-        # does not type cast
-        assert avg == '[2.5,3.5,4.5]'
+        avg = Item.select(fn.avg(Item.embedding).coerce(True)).scalar()
+        assert np.array_equal(avg, np.array([2.5, 3.5, 4.5]))
 
     def test_vector_sum(self):
-        sum = Item.select(fn.sum(Item.embedding)).scalar()
+        sum = Item.select(fn.sum(Item.embedding).coerce(True)).scalar()
         assert sum is None
         Item.create(embedding=[1, 2, 3])
         Item.create(embedding=[4, 5, 6])
-        sum = Item.select(fn.sum(Item.embedding)).scalar()
-        # does not type cast
-        assert sum == '[5,7,9]'
+        sum = Item.select(fn.sum(Item.embedding).coerce(True)).scalar()
+        assert np.array_equal(sum, np.array([5, 7, 9]))
 
     def test_halfvec_avg(self):
-        avg = Item.select(fn.avg(Item.half_embedding)).scalar()
+        avg = Item.select(fn.avg(Item.half_embedding).coerce(True)).scalar()
         assert avg is None
         Item.create(half_embedding=[1, 2, 3])
         Item.create(half_embedding=[4, 5, 6])
-        avg = Item.select(fn.avg(Item.half_embedding)).scalar()
-        # does not type cast
-        assert avg == '[2.5,3.5,4.5]'
+        avg = Item.select(fn.avg(Item.half_embedding).coerce(True)).scalar()
+        assert avg.to_list() == [2.5, 3.5, 4.5]
 
     def test_halfvec_sum(self):
-        sum = Item.select(fn.sum(Item.half_embedding)).scalar()
+        sum = Item.select(fn.sum(Item.half_embedding).coerce(True)).scalar()
         assert sum is None
         Item.create(half_embedding=[1, 2, 3])
         Item.create(half_embedding=[4, 5, 6])
-        sum = Item.select(fn.sum(Item.half_embedding)).scalar()
-        # does not type cast
-        assert sum == '[5,7,9]'
+        sum = Item.select(fn.sum(Item.half_embedding).coerce(True)).scalar()
+        assert sum.to_list() == [5, 7, 9]
 
     def test_get_or_create(self):
         Item.get_or_create(id=1, defaults={'embedding': [1, 2, 3]})