Range#
Versioned name: Range-4
Category: Generation
Short description: Range operation generates a sequence of numbers according input values [start, stop) with a step.
Attributes:
output_type
Description: the output tensor type
Range of values: any numeric type
Type: string
Required: yes
Inputs:
1: “start” - A scalar of type T1. Required.
2: “stop” - A scalar of type T2. Required.
3: “step” - A scalar of type T3. If
step
is equal to zero after casting tooutput_type
, behavior is undefined. Required.
Outputs:
1: A tensor with type specified by attribute output_type.
Types
T1, T2, T3: any numeric type.
Detailed description:
Range operation generates a sequence of numbers starting from the value in the first input (start
) up to but not including the value in the second input (stop
) with a step
equal to the value in the third input, according to the following formula:
For a positive step
:
for a negative step
:
the i-th element is calculated by the following formula:
The calculations are done after casting all values to accumulate_type(output_type)
. accumulate_type
is a type that have better or equal accuracy for accumulation than output_type
on current hardware, e.g. fp64
for fp16
. The number of elements is calculated in the floating-point type according to the following formula:
This is aligned with PyTorch’s operation torch.arange
, to align with tensorflow operation tf.range
all inputs must be casted to output_type
before calling Range. The rounding for casting values are done towards zero.
Examples
Example 1: positive step
<layer ... type="Range">
<data output_type="i32">
<input>
<port id="0"> <!-- start value: 2 -->
</port>
<port id="1"> <!-- stop value: 23 -->
</port>
<port id="2"> <!-- step value: 3 -->
</port>
</input>
<output>
<port id="3">
<dim>7</dim> <!-- [ 2, 5, 8, 11, 14, 17, 20] -->
</port>
</output>
</layer>
Example 2: negative step
<layer ... type="Range">
<data output_type="i32">
<input>
<port id="0"> <!-- start value: 23 -->
</port>
<port id="1"> <!-- stop value: 2 -->
</port>
<port id="2"> <!-- step value: -3 -->
</port>
</input>
<output>
<port id="3">
<dim>7</dim> <!-- [23, 20, 17, 14, 11, 8, 5] -->
</port>
</output>
</layer>
Example 3: floating-point
<layer ... type="Range">
<data output_type="f32">
<input>
<port id="0"> <!-- start value: 1 -->
</port>
<port id="1"> <!-- stop value: 2.5 -->
</port>
<port id="2"> <!-- step value: 0.5 -->
</port>
</input>
<output>
<port id="3">
<dim>3</dim> <!-- [ 1.0, 1.5, 2.0] -->
</port>
</output>
</layer>