def test_min_back(a, num_axes, keepdims):
""" Test Tensor.min for arbitrary data, axis, and keepdim"""
if num_axes == 0:
axes = None
else:
axes = np.random.choice(range(0, a.ndim), size=min(num_axes, a.ndim), replace=False)
axes = tuple(sorted(axes))
# single global minimum
if axes is None or axes == tuple(range(a.ndim)):
index = tuple(np.random.choice(i.flat) for i in np.indices(a.shape))
a[index] = a.min() - 1
grad = np.zeros_like(a)
grad[index] = 1
a = Tensor(a)
out = a.min(axis=axes, keepdims=keepdims)
out.backward()
assert np.allclose(grad, a.grad)
return None
# explicitly place maxima within tensor
static_axes = tuple(sorted(set(range(a.ndim)) - set(axes)))
static_shape = tuple(a.shape[i] for i in static_axes)
red_shapes = tuple(a.shape[i] for i in axes)
sorter = np.argsort(static_axes + axes)
# generate indices to span static axes
static_indices = tuple(i for i in np.indices(static_shape))
# generate random index-runs along reduction axes
choose_indices = tuple(np.random.choice(range(i), size=static_indices[0].shape) for i in red_shapes)
# create index tuple the selects random runs along reduction axes
static_indices += choose_indices
indices = []
for i in sorter:
indices.append(static_indices[i])
indices = tuple(indices)
# place extrema
a[indices] = a.min() - np.random.rand(*indices[0].shape)
a = Tensor(a)
out = a.min(axis=axes)
# break degeneracy amongst grad values
tmp = np.arange(1, out.data.size+1).reshape(out.shape)
out2 = out * tmp
out2.backward()
grad = np.zeros_like(a.data)
grad[indices] = np.arange(1, out.data.size+1).reshape(out.shape)
assert np.allclose(grad, a.grad)
def test_degenerate_min_back(fill_val, shape, num_axes, keepdims):
""" test min backprop for degenerate-valued tensors"""
a = Tensor(np.full(shape=shape, fill_value=fill_val, dtype=float))
if num_axes == 0:
axes = None
else:
axes = tuple(np.random.choice(range(0, a.ndim), size=min(num_axes, a.ndim), replace=False))
out = a.min(axis=axes, keepdims=keepdims)
out2 = out * np.arange(1, 1 + out.data.size).reshape(out.shape)
out2.backward()
grad = np.zeros_like(a.data)
if a.ndim == 0:
assert a.grad == 1.
return None
if out.ndim == 0:
grad[tuple(0 for i in range(a.ndim))] = 1
assert np.allclose(grad, a.grad)
else:
index = [slice(None) for i in range(a.ndim)]
if axes is None:
index = [0 for i in range(len(index))]
else:
for i in axes:
index[i] = 0
index = tuple(index)
shape = a.data.min(axis=axes).shape
grad[index] = np.arange(1, 1 + out.data.size).reshape(shape)
assert np.allclose(grad, a.grad)
def test_min_fwd(a, num_axes, keepdims):
a = Tensor(a)
if num_axes == 0:
axes = None
else:
axes = tuple(np.random.choice(range(0, a.ndim), size=min(num_axes, a.ndim), replace=False))
np_out = a.data.min(axis=axes, keepdims=keepdims)
pygrad_out = a.min(axis=axes, keepdims=keepdims).data
if pygrad_out.ndim == 0:
pygrad_out = np.asscalar(pygrad_out)
assert np.allclose(np_out, pygrad_out)
if num_axes:
neg_axes = tuple(np.random.choice(range(-a.ndim, 0), size=min(num_axes, a.ndim), replace=False))
np_out = a.data.min(axis=neg_axes, keepdims=keepdims)
pygrad_out = a.min(axis=neg_axes, keepdims=keepdims).data
if pygrad_out.ndim == 0:
pygrad_out = np.asscalar(pygrad_out)
assert np.allclose(np_out, pygrad_out)