If#
Versioned name: If-8
Category: Condition
Short description: If operation contains two internal networks(subgraphs) such as then_body
and else_body
,
and performs one of them depending on cond
value. If cond
is True
, then_body
is executed. If cond
is False
,
the operation executes the else_body
subgraph.
Detailed description
If must not contain empty subgraphs. Each of them must have at least one operation Result
.
Also the number of outputs from If always must be greater than zero and equal to the number of outputs from each subgraph.
If attributes:
Subgraphs:
then_body
/else_body
are subgraphs that are executed depending on thecond
value. The subgraph is described operation by operation as a typical IR network. The subgraph has inputs (Parameter
operations) and outputs (Result
operations).Subgraph’s inputs - inputs to the subgraph which associated with If inputs via port_map.
The subgraph can have any number of inputs (even zero).
Subgraph’s outputs - outputs from the subgraph which associated with If outputs via port_map.
The subgraph must contain at least one output. Each If output is associated with one output from the subgraph. Therefore the number of
then_body
outputs is equal to the number of outputs from If and the number ofelse_body
outputs. The type of the subgraph output and the type of the associated output from If must be equal.
Port maps:
port_map is a set of rules to map input or output data tensors of If operation onto the subgraph data tensors. The
port_map
entries can beinput
andoutput
. Each entry describes a corresponding mapping rule. If has two port_maps:then_port_map
forthen_body
andelse_port_map
forelse_body
.Port map attributes:
external_port_id
Description: external_port_id is a port ID of If operation.
Range of values: IDs of the If inputs and outputs
Type:
unsigned int
Default value: None
Required: yes
internal_layer_id
Description: internal_layer_id is a
Parameter
orResult
operation ID inside the subgraph to map to.Range of values: IDs of the
Parameter
orResult
operations in the subgraphType:
unsigned int
Default value: None
Required: yes
If Inputs
cond: A scalar or 1D tensor with 1 element of
boolean
type specifying which subgraph to execute.True
value means to execute thethen_body
,False
-else_body
. Required.Multiple other inputs: Tensors of different types and shapes. Optional.
If Outputs
Multiple outputs: Results of execution of one of the subgraph. Tensors of any type and shape.
Body Inputs
Multiple inputs: Tensors of different types and shapes. Optional.
Body Outputs
Multiple outputs: Results of execution of the subgraph. Tensors of any type and shape.
Examples
Example 1: a typical If structure
<layer id="6" name="if/cond" type="If" version="opset8">
<input>
<port id="0"/>
<port id="1">
<dim>2</dim>
<dim>4</dim>
</port>
<port id="2">
<dim>2</dim>
<dim>4</dim>
</port>
<port id="3">
<dim>2</dim>
<dim>4</dim>
</port>
</input>
<output>
<port id="4" names="if/cond/Identity:0,if/cond:0" precision="FP32">
<dim>2</dim>
<dim>4</dim>
</port>
</output>
<then_port_map>
<input external_port_id="1" internal_layer_id="0"/>
<input external_port_id="2" internal_layer_id="1"/>
<output external_port_id="0" internal_layer_id="3"/>
</then_port_map>
<else_port_map>
<input external_port_id="1" internal_layer_id="0"/>
<input external_port_id="3" internal_layer_id="1"/>
<output external_port_id="0" internal_layer_id="3"/>
</else_port_map>
<then_body>
<layers>
<layer id="0" name="add_x" type="Parameter" version="opset1">
<data element_type="f32" shape="2,4"/>
<output>
<port id="0" names="add_x:0" precision="FP32">
<dim>2</dim>
<dim>4</dim>
</port>
</output>
</layer>
<layer id="1" name="add_z" type="Parameter" version="opset1">
<data element_type="f32" shape="2,4"/>
<output>
<port id="0" names="add_z:0" precision="FP32">
<dim>2</dim>
<dim>4</dim>
</port>
</output>
</layer>
<layer id="2" name="Add" type="Add" version="opset1">
<data auto_broadcast="numpy"/>
<input>
<port id="0">
<dim>2</dim>
<dim>4</dim>
</port>
<port id="1">
<dim>2</dim>
<dim>4</dim>
</port>
</input>
<output>
<port id="2" names="Add:0" precision="FP32">
<dim>2</dim>
<dim>4</dim>
</port>
</output>
</layer>
<layer id="3" name="Identity/sink_port_0" type="Result" version="opset1">
<input>
<port id="0">
<dim>2</dim>
<dim>4</dim>
</port>
</input>
</layer>
</layers>
<edges>
<edge from-layer="0" from-port="0" to-layer="2" to-port="0"/>
<edge from-layer="1" from-port="0" to-layer="2" to-port="1"/>
<edge from-layer="2" from-port="2" to-layer="3" to-port="0"/>
</edges>
</then_body>
<else_body>
<layers>
<layer id="0" name="add_x" type="Parameter" version="opset1">
<data element_type="f32" shape="2,4"/>
<output>
<port id="0" names="add_x:0" precision="FP32">
<dim>2</dim>
<dim>4</dim>
</port>
</output>
</layer>
<layer id="1" name="add_w" type="Parameter" version="opset1">
<data element_type="f32" shape="2,4"/>
<output>
<port id="0" names="add_w:0" precision="FP32">
<dim>2</dim>
<dim>4</dim>
</port>
</output>
</layer>
<layer id="2" name="Add" type="Add" version="opset1">
<data auto_broadcast="numpy"/>
<input>
<port id="0">
<dim>2</dim>
<dim>4</dim>
</port>
<port id="1">
<dim>2</dim>
<dim>4</dim>
</port>
</input>
<output>
<port id="2" names="Add:0" precision="FP32">
<dim>2</dim>
<dim>4</dim>
</port>
</output>
</layer>
<layer id="3" name="Identity/sink_port_0" type="Result" version="opset1">
<input>
<port id="0">
<dim>2</dim>
<dim>4</dim>
</port>
</input>
</layer>
</layers>
<edges>
<edge from-layer="0" from-port="0" to-layer="2" to-port="0"/>
<edge from-layer="1" from-port="0" to-layer="2" to-port="1"/>
<edge from-layer="2" from-port="2" to-layer="3" to-port="0"/>
</edges>
</else_body>
</layer>