def test_slice():
element_type = Type.f32
shape = Shape([6, 6])
A = Parameter(element_type, shape)
parameter_list = [A]
input_arr = np.arange(36, dtype=np.float32).reshape(6, 6)
lower_bounds = [1, 1]
upper_bounds = [5, 5]
function = Function(
NodeVector(
[Slice(A, Coordinate(lower_bounds), Coordinate(upper_bounds))]),
parameter_list, 'test')
backend = Backend.create(test.BACKEND_NAME)
a = backend.create_tensor(element_type, shape)
result = backend.create_tensor(element_type, Shape([4, 4]))
a.write(util.numpy_to_c(input_arr), 0, 36 * 4)
result_arr = np.zeros(16, dtype=np.float32).reshape(4, 4)
result.write(util.numpy_to_c(result_arr), 0, 16 * 4)
handle = backend.compile(function)
handle.call([result], [a])
result.read(util.numpy_to_c(result_arr), 0, 64)
result_arr_ref = input_arr[lower_bounds[0]:upper_bounds[0],
lower_bounds[1]:upper_bounds[1]]
assert np.allclose(result_arr, result_arr_ref)
#test with strides
strides = [1, 2]
function = Function(
NodeVector([
Slice(A, Coordinate(lower_bounds), Coordinate(upper_bounds),
Strides(strides))
]), parameter_list, 'test')
backend = Backend.create(test.BACKEND_NAME)
result = backend.create_tensor(element_type, Shape([4, 2]))
result_arr = np.zeros(8, dtype=np.float32).reshape(4, 2)
result.write(util.numpy_to_c(result_arr), 0, 8 * 4)
handle = backend.compile(function)
handle.call([result], [a])
result.read(util.numpy_to_c(result_arr), 0, 32)
result_arr_ref = result_arr_ref[::strides[0], ::strides[1]]
assert np.allclose(result_arr, result_arr_ref)
def slice(node, lower_bounds, upper_bounds, strides=None, name=None):
# type: (Node, List[int], List[int], List[int], str) -> Node
"""Take a slice of an input tensor, (sub-tensor) that resides within a bounding box.
Optionally this function may be provided with stride along each axis.
:param node: The tensor we want to slice.
:param lower_bounds: The (inclusive) lower-bound coordinates for the tensor slice.
:param upper_bounds: The (exclusive) upper-bound coordinates for the tensor slice.
:param strides: The strides for the tensor slice.
:param name: Optional name for the output node.
:return: Return node that represents a slice of input nodes data.
"""
if strides is None:
return Slice(node, Coordinate(lower_bounds), Coordinate(upper_bounds))
else:
return Slice(node, Coordinate(lower_bounds), Coordinate(upper_bounds), Strides(strides))