Sample python bilinear initializer at integral points in y-direction (a…

…pache#12983)

* Sample python bilinear initializer at integral points in y-direction

* Add unit test for bilinear initializer

python/mxnet/initializer.py

@@ -217,7 +217,7 @@ def _init_bilinear(self, _, arr):
         c = (2 * f - 1 - f % 2) / (2. * f)
         for i in range(np.prod(shape)):
             x = i % shape[3]
-            y = (i / shape[3]) % shape[2]
+            y = (i // shape[3]) % shape[2]
             weight[i] = (1 - abs(x / f - c)) * (1 - abs(y / f - c))
         arr[:] = weight.reshape(shape)
 
@@ -657,7 +657,7 @@ def _init_weight(self, _, arr):
         c = (2 * f - 1 - f % 2) / (2. * f)
         for i in range(np.prod(shape)):
             x = i % shape[3]
-            y = (i / shape[3]) % shape[2]
+            y = (i // shape[3]) % shape[2]
             weight[i] = (1 - abs(x / f - c)) * (1 - abs(y / f - c))
         arr[:] = weight.reshape(shape)
 

tests/python/unittest/test_init.py

@@ -60,8 +60,17 @@ def check_rsp_const_init(init, val):
     check_rsp_const_init(mx.initializer.Zero(), 0.)
     check_rsp_const_init(mx.initializer.One(), 1.)
 
+def test_bilinear_init():
+    bili = mx.init.Bilinear()
+    bili_weight = mx.ndarray.empty((1,1,4,4))
+    bili._init_weight(None, bili_weight)
+    bili_1d = np.array([[1/float(4), 3/float(4), 3/float(4), 1/float(4)]])
+    bili_2d = bili_1d * np.transpose(bili_1d)
+    assert (bili_2d == bili_weight.asnumpy()).all()
+
 if __name__ == '__main__':
     test_variable_init()
     test_default_init()
     test_aux_init()
     test_rsp_const_init()
+    test_bilinear_init()