Slice#
Versioned name: Slice-8
Category: Data movement
Short description: Slice operation extracts a slice of the input tensor.
Detailed Description: Slice operation selects a region of values from the data
tensor.
Selected values start at indexes provided in the start
input (inclusively) and end
at indexes provides in stop
input (exclusively).
The step
input allows subsampling of data
, selecting every n-th element,
where n
is equal to step
element for corresponding axis.
Negative step
value indicates slicing backwards, so the sequence along the corresponding axis is reversed in the output tensor.
To select all values contiguously set step
to 1
for each axis.
The optional axes
input allows specifying slice indexes only on selected axes.
Other axes will not be affected and will be output in full.
The rules follow python language slicing data[start:stop:step]
.
Attributes: Slice operation has no attributes.
Inputs
1:
data
- tensor (to be sliced) of type T and shape rank greater or equal to 1. Required.2:
start
- 1D tensor of type T_IND. Indices corresponding to axes indata
.Defines the starting coordinate of the slice in the
data
tensor. A negative index value represents counting elements from the end of that dimension. A value larger than the size of a dimension is silently clamped. Required.3:
stop
- 1D, type T_IND, similar tostart
.Defines the coordinate of the opposite vertex of the slice, or where the slice ends. Stop indexes are exclusive, which means values lying on the ending edge are not included in the output slice. To slice to the end of a dimension of unknown size
INT_MAX
may be used (orINT_MIN
if slicing backwards). Required.4:
step
- 1D tensor of type T_IND and the same shape asstart
andstop
.Integer value that specifies the increment between each index used in slicing. Value cannot be
0
, negative value indicates slicing backwards. Required.5:
axes
- 1D tensor of type T_AXIS.Optional 1D tensor indicating which dimensions the values in
start
andstop
apply to. Negative value means counting dimensions from the end. The range is[-r, r - 1]
, wherer
is the rank of thedata
input tensor. Values are required to be unique. If a particular axis is unspecified, it will be output in full and not sliced. Default value:[0, 1, 2, ..., start.shape[0] - 1]
. Optional.
Number of elements in start
, stop
, step
, and axes
inputs are required to be equal.
Outputs
1: Tensor of type T with values of the selected slice. The shape of the output tensor has the same rank as the shape of
data
input and reduced dimensions according to the values specified bystart
,stop
, andstep
inputs.
Types
T: any arbitrary supported type.
T_IND: any supported integer type.
T_AXIS: any supported integer type.
Examples
Example 1: basic slicing
<layer id="1" type="Slice" ...>
<input>
<port id="0"> <!-- data: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] -->
<dim>10</dim>
</port>
<port id="1"> <!-- start: [1] -->
<dim>1</dim>
</port>
<port id="2"> <!-- stop: [8] -->
<dim>1</dim>
</port>
<port id="3"> <!-- step: [1] -->
<dim>1</dim>
</port>
<port id="4"> <!-- axes: [0] -->
<dim>1</dim>
</port>
</input>
<output>
<port id="5"> <!-- output: [1, 2, 3, 4, 5, 6, 7] -->
<dim>7</dim>
</port>
</output>
</layer>
Example 2: basic slicing, axes
default
<layer id="1" type="Slice" ...>
<input>
<port id="0"> <!-- data: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] -->
<dim>10</dim>
</port>
<port id="1"> <!-- start: [1] -->
<dim>1</dim>
</port>
<port id="2"> <!-- stop: [8] -->
<dim>1</dim>
</port>
<port id="3"> <!-- step: [1] -->
<dim>1</dim>
</port>
</input>
<output>
<port id="4"> <!-- output: [1, 2, 3, 4, 5, 6, 7] -->
<dim>7</dim>
</port>
</output>
</layer>
Example 3: basic slicing, step: [2]
<layer id="1" type="Slice" ...>
<input>
<port id="0"> <!-- data: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] -->
<dim>10</dim>
</port>
<port id="1"> <!-- start: [1] -->
<dim>1</dim>
</port>
<port id="2"> <!-- stop: [8] -->
<dim>1</dim>
</port>
<port id="3"> <!-- step: [2] -->
<dim>1</dim>
</port>
<port id="4"> <!-- axes: [0] -->
<dim>1</dim>
</port>
</input>
<output>
<port id="5"> <!-- output: [1, 3, 5, 7] -->
<dim>4</dim>
</port>
</output>
</layer>
Example 4: start
and stop
out of the dimension size, step: [1]
<layer id="1" type="Slice" ...>
<input>
<port id="0"> <!-- data: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] -->
<dim>10</dim>
</port>
<port id="1"> <!-- start: [-100] -->
<dim>1</dim>
</port>
<port id="2"> <!-- stop: [100] -->
<dim>1</dim>
</port>
<port id="3"> <!-- step: [1] -->
<dim>1</dim>
</port>
<port id="4"> <!-- axes: [0] -->
<dim>1</dim>
</port>
</input>
<output>
<port id="5"> <!-- output: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] -->
<dim>10</dim>
</port>
</output>
</layer>
Example 5: slicing backward all elements, step: [-1]
, stop: [-11]
<layer id="1" type="Slice" ...>
<input>
<port id="0"> <!-- data: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] -->
<dim>10</dim>
</port>
<port id="1"> <!-- start: [9] -->
<dim>1</dim>
</port>
<port id="2"> <!-- stop: [-11] -->
<dim>1</dim>
</port>
<port id="3"> <!-- step: [-1] -->
<dim>1</dim>
</port>
<port id="4"> <!-- axes: [0] -->
<dim>1</dim>
</port>
</input>
<output>
<port id="5"> <!-- output: [9, 8, 7, 6, 5, 4, 3, 2, 1, 0] -->
<dim>10</dim>
</port>
</output>
</layer>
Example 6: slicing backward, step: [-1]
, stop: [0]
<layer id="1" type="Slice" ...>
<input>
<port id="0"> <!-- data: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] -->
<dim>10</dim>
</port>
<port id="1"> <!-- start: [9] -->
<dim>1</dim>
</port>
<port id="2"> <!-- stop: [0] -->
<dim>1</dim>
</port>
<port id="3"> <!-- step: [-1] -->
<dim>1</dim>
</port>
<port id="4"> <!-- axes: [0] -->
<dim>1</dim>
</port>
</input>
<output>
<port id="5"> <!-- output: [9, 8, 7, 6, 5, 4, 3, 2, 1] -->
<dim>9</dim>
</port>
</output>
</layer>
Example 7: slicing backward, step: [-1]
, stop: [-10]
<layer id="1" type="Slice" ...>
<input>
<port id="0"> <!-- data: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] -->
<dim>10</dim>
</port>
<port id="1"> <!-- start: [9] -->
<dim>1</dim>
</port>
<port id="2"> <!-- stop: [-10] -->
<dim>1</dim>
</port>
<port id="3"> <!-- step: [-1] -->
<dim>1</dim>
</port>
<port id="4"> <!-- axes: [0] -->
<dim>1</dim>
</port>
</input>
<output>
<port id="5"> <!-- output: [9, 8, 7, 6, 5, 4, 3, 2, 1] -->
<dim>9</dim>
</port>
</output>
</layer>
Example 8: slicing backward, step: [-2]
<layer id="1" type="Slice" ...>
<input>
<port id="0"> <!-- data: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] -->
<dim>10</dim>
</port>
<port id="1"> <!-- start: [9] -->
<dim>1</dim>
</port>
<port id="2"> <!-- stop: [-11] -->
<dim>1</dim>
</port>
<port id="3"> <!-- step: [-2] -->
<dim>1</dim>
</port>
<port id="4"> <!-- axes: [0] -->
<dim>1</dim>
</port>
</input>
<output>
<port id="5"> <!-- output: [9, 7, 5, 3, 1] -->
<dim>5</dim>
</port>
</output>
</layer>
Example 9: start
and stop
out of the dimension size, slicing backward
<layer id="1" type="Slice" ...>
<input>
<port id="0"> <!-- data: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] -->
<dim>10</dim>
</port>
<port id="1"> <!-- start: [100] -->
<dim>1</dim>
</port>
<port id="2"> <!-- stop: [-100] -->
<dim>1</dim>
</port>
<port id="3"> <!-- step: [-1] -->
<dim>1</dim>
</port>
<port id="4"> <!-- axes: [0] -->
<dim>1</dim>
</port>
</input>
<output>
<port id="5"> <!-- output: [9, 8, 7, 6, 5, 4, 3, 2, 1, 0] -->
<dim>10</dim>
</port>
</output>
</layer>
Example 10: slicing 2D tensor, all axes specified
<layer id="1" type="Slice" ...>
<input>
<port id="0"> <!-- data: data: [[0, 1, 2, 3, 4], [5, 6, 7, 8, 9]] -->
<dim>2</dim>
<dim>5</dim>
</port>
<port id="1"> <!-- start: [0, 1] -->
<dim>2</dim>
</port>
<port id="2"> <!-- stop: [2, 4] -->
<dim>2</dim>
</port>
<port id="3"> <!-- step: [1, 2] -->
<dim>2</dim>
</port>
<port id="4"> <!-- axes: [0, 1] -->
<dim>2</dim>
</port>
</input>
<output>
<port id="5"> <!-- output: [1, 3, 6, 8] -->
<dim>2</dim>
<dim>2</dim>
</port>
</output>
</layer>
Example 11: slicing 3D tensor, all axes specified
<layer id="1" type="Slice" ...>
<input>
<port id="0"> <!-- data -->
<dim>20</dim>
<dim>10</dim>
<dim>5</dim>
</port>
<port id="1"> <!-- start: [0, 0, 0] -->
<dim>2</dim>
</port>
<port id="2"> <!-- stop: [4, 10, 5] -->
<dim>2</dim>
</port>
<port id="3"> <!-- step: [1, 1, 1] -->
<dim>2</dim>
</port>
<port id="4"> <!-- axes: [0, 1, 2] -->
<dim>2</dim>
</port>
</input>
<output>
<port id="5"> <!-- output -->
<dim>4</dim>
<dim>10</dim>
<dim>5</dim>
</port>
</output>
</layer>
Example 12: slicing 3D tensor, last axes default
<layer id="1" type="Slice" ...>
<input>
<port id="0"> <!-- data -->
<dim>20</dim>
<dim>10</dim>
<dim>5</dim>
</port>
<port id="1"> <!-- start: [0, 0] -->
<dim>2</dim>
</port>
<port id="2"> <!-- stop: [4, 10] -->
<dim>2</dim>
</port>
<port id="3"> <!-- step: [1, 1] -->
<dim>2</dim>
</port>
<port id="4"> <!-- axes: [0, 1] -->
<dim>2</dim>
</port>
</input>
<output>
<port id="5"> <!-- output -->
<dim>4</dim>
<dim>10</dim>
<dim>5</dim>
</port>
</output>
</layer>