io.improbable.keanu.templating.loop

Class Loop

java.lang.Object

io.improbable.keanu.templating.loop.Loop

public class Loop
extends java.lang.Object

A Loop object is a convenient wrapper around some Sequence. See LoopTest.java for examples of how it's used. The way it works is to unroll the loop to a given maximum size and evaluate it in full (so it's not very performant)

The resulting graph structure looks like this. "base" is the base case, provided by the user "cond" is the condition (one instance per iteration), provided by the user "iterate" is the iteration step, provided by the user "V" is the output of the loop "L" indicates if it's still looping. This is used to detect the error case in which the loop was too short to complete.

cond true base \ | | \ AND | iterate |\ | /| | \ | / | cond | IF | \ | |\ | AND | iterate |\ | /| | \ | / | cond | IF | \ | |\ | AND | iterate |\ | / | \ | / | IF | | L V

Field Summary

Fields

Modifier and Type	Field and Description
static VertexLabel	CONDITION_LABEL
static int	DEFAULT_MAX_COUNT
static VertexLabel	LOOP_LABEL
static VertexLabel	VALUE_IN_LABEL
static VertexLabel	VALUE_OUT_LABEL

Method Summary

Modifier and Type	Method and Description
<V extends Vertex<?>> V	getOutput()
Sequence	getSequence()
static LoopBuilder	withInitialConditions(VertexDictionary initialState) A factory method for creating a loop
static <V extends Vertex<?>> LoopBuilder	withInitialConditions(V first, V... others) A factory method for creating a loop

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

VALUE_OUT_LABEL

public static final VertexLabel VALUE_OUT_LABEL

VALUE_IN_LABEL

public static final VertexLabel VALUE_IN_LABEL

CONDITION_LABEL

public static final VertexLabel CONDITION_LABEL

LOOP_LABEL

public static final VertexLabel LOOP_LABEL

DEFAULT_MAX_COUNT

public static final int DEFAULT_MAX_COUNT

See Also:

Constant Field Values

Method Detail

getSequence

public Sequence getSequence()

withInitialConditions

public static <V extends Vertex<?>> LoopBuilder withInitialConditions(V first,
                                                                      V... others)

A factory method for creating a loop

Type Parameters:

V - the input type

Parameters:

first - the first Vertex (mandatory)

others - other Vertices (optional)

Returns:

a builder object

withInitialConditions

public static LoopBuilder withInitialConditions(VertexDictionary initialState)

A factory method for creating a loop

Parameters:

initialState - the collection of vertices that define the loop's base case

Returns:

a builder object

getOutput

public <V extends Vertex<?>> V getOutput()
                                  throws LoopDidNotTerminateException

Type Parameters:

V - the output type

Returns:

the output of the Loop (i.e. the output Vertex from the final SequenceItem)

Throws:

LoopDidNotTerminateException - if the loop was too short and hit its maximum unrolled size