Add pack and unpack

mindspore/ccsrc/operator/ops.h

@@ -135,6 +135,7 @@ extern const PrimitivePtr kPrimGatherV2;
 extern const PrimitivePtr kPrimSize;
 extern const PrimitivePtr kPrimArgMax;
 extern const PrimitivePtr kPrimPack;
+extern const PrimitivePtr kPrimUnpack;
 extern const PrimitivePtr kPrimUnsortedSegmentSum;
 extern const PrimitivePtr kPrimConcatOffset;
 extern const PrimitivePtr kPrimReshape;

mindspore/ccsrc/transform/convert.cc

@@ -148,7 +148,8 @@ const char kNameSlice[] = "Slice";
 const char kNameAddN[] = "AddN";
 const char kNameLess[] = "Less";
 const char kNameGreater[] = "Greater";
-const char kNamePack[] = "Stack";
+const char kNameStack[] = "Stack";
+const char kNameUnstack[] = "Unstack";
 const char kNameMerge[] = "Merge";
 const char kNameGeSwitch[] = "GeSwitch";
 

mindspore/ops/_grad/grad_array_ops.py

@@ -266,6 +266,30 @@ def get_bprop_gather_v2(self):
     return bprop
 
 
+@bprop_getters.register(P.Stack)
+def get_bprop_stack(self):
+    """Generate bprop for Stack"""
+    axis = self.axis
+
+    def bprop(x, out, dout):
+        stack_grad = P.Unstack(axis)
+        out = stack_grad(dout)
+        return (out,)
+    return bprop
+
+
+@bprop_getters.register(P.Unstack)
+def get_bprop_unstack(self):
+    """Generate bprop for Unstack"""
+    axis = self.axis
+
+    def bprop(x, out, dout):
+        unstack_grad = P.Stack(axis)
+        out = unstack_grad(dout)
+        return (out,)
+    return bprop
+
+
 @bprop_getters.register(P.StridedSlice)
 def get_bprop_strided_slice(self):
     """Generate bprop for StridedSlice"""

mindspore/ops/operations/__init__.py

@@ -19,7 +19,7 @@ Primitive operator classes.
 A collection of operators to build nerual networks or computing functions.
 """
 
-from .array_ops import (Argmax, Argmin, Cast, ConcatOffset, Concat,
+from .array_ops import (Argmax, Argmin, Cast, ConcatOffset, Concat, Stack, Unstack,
                         Diag, DiagPart, DType, ExpandDims, Eye,
                         Fill, GatherNd, GatherV2, InvertPermutation,
                         IsInstance, IsSubClass, ArgMaxWithValue, OnesLike, ZerosLike,
@@ -112,6 +112,8 @@ __all__ = [
     'OneHot',
     'GatherV2',
     'Concat',
+    'Stack',
+    'Unstack',
     'Tile',
     'BiasAdd',
     'Gelu',

mindspore/ops/operations/array_ops.py

@@ -1350,6 +1350,150 @@ class Concat(PrimitiveWithInfer):
         return out
 
 
+def _get_stack_shape(x_shape, x_type, axis):
+    """for satck output shape"""
+    validator.check_type("shape", x_shape, [tuple])
+    validator.check_integer("len of input_x shape", len(x_shape), 0, Rel.GT)
+    validator.check_subclass("shape0", x_type[0], mstype.tensor)
+    validator.check_integer("len of input_x0 shape", len(x_shape[0]), 0, Rel.GT)
+    rank_base = len(x_shape[0])
+    N = len(x_shape)
+    out_shape = x_shape[0]
+    validator.check_int_range('axis', axis, -rank_base - 1, rank_base, Rel.INC_BOTH)
+    if axis < 0:
+        axis = axis + rank_base + 1
+    for i in range(1, N):
+        v = x_shape[i]
+        validator.check('len of x_shape[%d]' % i, len(v), 'len of rank_base', rank_base)
+        validator.check('x_type[%d]' % i, x_type[i], 'base', x_type[0])
+        for j in range(rank_base):
+            if v[j] != x_shape[0][j]:
+                raise ValueError("Stack evaluator element %d shape in input can not stack with first element" % i)
+    out_shape.insert(axis, N)
+    return out_shape
+
+class Stack(PrimitiveWithInfer):
+    r"""
+    Stacks a list of rank-`R` tensors into one rank-`(R+1)` tensor.
+
+    Packs the list of tensors in `input_x` into a tensor with rank one higher than
+    each tensor in `input_x`, by packing them along the `axis` dimension.
+    Given a list of length `N` of tensors of shape `(A, B, C)`;
+
+    If `axis == 0` then the `output` tensor will have the shape `(N, A, B, C)`.
+
+    If `axis == 1` then the `output` tensor will have the shape `(A, N, B, C)`. Etc.
+
+    Args:
+        axis (int): The axis to stack along. Negative values wrap around,
+                    so the valid range is [-(R+1), R+1). Default: 0.
+
+    Inputs:
+        - **input_x** (Union[tuple, list]) - A Tuple or list of Tensor objects with the same shape and type.
+
+    Outputs:
+        Tensor. A stacked Tensor with the same type as values.
+
+    Examples:
+        >>> data1 = Tensor(np.array([0, 1]).astype(np.float32))
+        >>> data2 = Tensor(np.array([2, 3]).astype(np.float32))
+        >>> op = P.Stack()
+        >>> output = op([data1, data2])
+        [[0, 1], [2, 3]]
+    """
+
+    @prim_attr_register
+    def __init__(self, axis=0):
+        """init Stack"""
+        self.__setattr_flag__ = True
+        validator.check_type("axis", axis, [int])
+        self.axis = axis
+
+    def __infer__(self, value):
+        x_shape = value['shape']
+        x_type = value['dtype']
+        self.add_prim_attr('num', len(x_shape))
+        all_shape = _get_stack_shape(x_shape, x_type, self.axis)
+        out = {'shape': all_shape,
+               'dtype': x_type[0],
+               'value': None}
+        return out
+
+
+class Unstack(PrimitiveWithInfer):
+    r"""
+    Unpacks the given dimension of a rank-`R` tensor into rank-`(R-1)` tensors.
+
+    Unpacks num tensors from value by chipping it along the axis dimension.
+    If num is not specified (the default), it is inferred from value's shape.
+    If value.shape[axis] is not known, ValueError is raised.
+
+    For example, given a tensor of shape (A, B, C, D);
+
+    If axis == 0 then the i'th tensor in output is the slice value[i, :, :, :] and
+    each tensor in output will have shape (B, C, D). (Note that the dimension unpacked along is gone, unlike split).
+
+    If axis == 1 then the i'th tensor in output is the slice value[:, i, :, :] and
+    each tensor in output will have shape (A, C, D). Etc.
+
+    This is the opposite of stack.
+
+    Args:
+        axis (int): The axis to unstack along. Defaults to the first dimension.
+                    Negative values wrap around, so the valid range is [-R, R).
+
+    Inputs:
+        - **input_x** (Tensor) - The shape is :math:`(x_1, x_2, ..., x_R)`.
+          A rank R > 0 Tensor to be unstacked.
+
+    Outputs:
+        A tuple of Tensors, the shape of each objects is same.
+
+    Raises:
+        ValueError: If axis is out of the range [-len(input_x.shape()), len(input_x.shape())),
+                    or if len(input_x.shape[axis]) not equal to num.
+
+    Examples:
+        >>> unstack = P.Unstack()
+        >>> x = Tensor(np.array([[1, 1, 1, 1], [2, 2, 2, 2]]))
+        >>> output = unstack(x)
+        ([1, 1, 1, 1], [2, 2, 2, 2])
+    """
+
+    @prim_attr_register
+    def __init__(self, axis=0):
+        """init Unstack"""
+        self.__setattr_flag__ = True
+        validator.check_type("axis", axis, [int])
+        self.axis = axis
+
+    def __infer__(self, x):
+        validator.check_subclass("x", x['dtype'], mstype.tensor)
+        x_shape = list(x['shape'])
+        dim = len(x_shape)
+        validator.check_int_range('axis value', self.axis, -dim, dim, Rel.INC_LEFT)
+        if self.axis < 0:
+            self.axis = self.axis + dim
+        output_num = x_shape[self.axis]
+        validator.check_type("num", output_num, [int])
+        validator.check_integer("output_num", output_num, 0, Rel.GT)
+        self.add_prim_attr('num', output_num)
+        output_valid_check = x_shape[self.axis] - output_num
+        validator.check_integer("the dimension which to unstack divides output_num", output_valid_check, 0, Rel.EQ)
+        out_shapes = []
+        out_dtypes = []
+        out_shape = x_shape[:self.axis] + x_shape[self.axis + 1:]
+        for _ in range(output_num):
+            out_shapes.append(tuple(out_shape))
+            out_dtypes.append(x['dtype'])
+        out_shapes = tuple(out_shapes)
+        out_dtypes = tuple(out_dtypes)
+        out = {'shape': out_shapes,
+               'dtype': out_dtypes,
+               'value': None}
+        return out
+
+
 class Slice(PrimitiveWithInfer):
     """
     Slice a tensor in specified shape.

tests/ut/python/ops/test_ops.py

@@ -80,6 +80,29 @@ class NetForConcat1(nn.Cell):
         return self.concat((x1, x2))
 
 
+class NetForStackInput(nn.Cell):
+    def __init__(self, op):
+        super(NetForStackInput, self).__init__()
+        self.op = op
+        self.mul = P.Mul()
+
+    def construct(self, *args):
+        t = ()
+        for i in range(len(args)):
+            t = t + (self.mul(args[i], args[i]),)
+        return self.op(t)
+
+
+class NetForUnstackInput(nn.Cell):
+    def __init__(self, op):
+        super(NetForUnstackInput, self).__init__()
+        self.op = op
+        self.mul = P.Mul()
+
+    def construct(self, x1):
+        return self.op((self.mul(x1, x1)))
+
+
 class NetForFlatten(nn.Cell):
     def __init__(self):
         super(NetForFlatten, self).__init__()
@@ -973,6 +996,36 @@ test_case_array_ops = [
                          Tensor(np.array([1], np.float32)),
                          Tensor(np.array([1], np.float32)))],
         'desc_bprop': [[3,]]}),
+    ('StackV2_0', {
+        'block': NetForStackInput(P.Stack()),
+        'desc_inputs':[[2, 2], [2, 2], [2, 2]],
+        'desc_bprop':[[3, 2, 2]],
+    }),
+    ('StackV2_1', {
+        'block': NetForStackInput(P.Stack(axis=-2)),
+        'desc_inputs':[[3, 2, 3], [3, 2, 3], [3, 2, 3]],
+        'desc_bprop':[[3, 2, 3, 3]],
+    }),
+    ('StackV2_2', {
+        'block': NetForStackInput(P.Stack()),
+        'desc_inputs':[[2, 2]],
+        'desc_bprop':[[2, 2, 2]],
+    }),
+    ('StackV2_3', {
+        'block': NetForStackInput(P.Stack()),
+        'desc_inputs':[[128, 128], [128, 128]],
+        'desc_bprop':[[2, 128, 128]],
+    }),
+    ('UnstackV2_0', {
+        'block': NetForUnstackInput(P.Unstack(axis=0)),
+        'desc_inputs':[[2, 4]],
+        'desc_bprop':[[4], [4]],
+    }),
+    ('UnstackV2_1', {
+        'block': NetForUnstackInput(P.Unstack(axis=-1)),
+        'desc_inputs':[Tensor(np.array([[1, 1, 1]], np.float32))],
+        'desc_bprop':[[1], [1], [1]],
+    }),
     ('Diag', {
         'block': P.Diag(),
         'desc_inputs': [[4]],