Links

Link

class nupic::Link

Represents a link between regions in a Network.

Inherits from nupic::Serializable< LinkProto >

Initialization

Links have four-phase initialization.

1. construct with link type, params, names of regions and inputs/outputs
2. wire in to network (setting src and dest Output/Input pointers)
3. set source and destination dimensions
4. initialize sets the offset in the destination Input (not known earlier)

De-serializing is the same as phase 1.

In phase 3, NuPIC will set and/or get source and/or destination dimensions until both are set. Normally we will only set the src dimensions, and the dest dimensions will be induced. It is possible to go the other way, though.

The linkType and linkParams parameters are given to the LinkPolicyFactory to create a link policy

Link(const std::string &linkType, const std::string &linkParams, const std::string &srcRegionName, const std::string &destRegionName, const std::string &srcOutputName = "", const std::string &destInputName = "", const size_t propagationDelay = 0)

Initialization Phase 1: setting parameters of the link.

Parameters

• linkType: The type of the link
• linkParams: The parameters of the link
• srcRegionName: The name of the source Region
• destRegionName: The name of the destination Region
• srcOutputName: The name of the source Output
• destInputName: The name of the destination Input
• propagationDelay: Propagation delay of the link as number of network run iterations involving the link as input; the delay vectors, if any, are initially populated with 0’s. Defaults to 0=no delay

Link()

De-serialization use case.

Creates a “blank” link. The caller must follow up with Link::read and Link::connectToNetwork

Parameters

• proto: LinkProto::Reader

void connectToNetwork(Output *src, Input *dest)

Initialization Phase 2: connecting inputs/outputs to the Network.

Parameters

• src: The source Output of the link
• dest: The destination Input of the link

void setSrcDimensions(Dimensions &dims)

Initialization Phase 3: set the Dimensions for the source Output, and induce the Dimensions for the destination Input .

Parameters

• dims: The Dimensions for the source Output

void setDestDimensions(Dimensions &dims)

Initialization Phase 3: Set the Dimensions for the destination Input, and induce the Dimensions for the source Output .

Parameters

• dims: The Dimensions for the destination Input

void initialize(size_t destinationOffset)

Initialization Phase 4: sets the offset in the destination Input .

Parameters

• destinationOffset: The offset in the destination Input, i.e. TODO

~Link()

Destructor.

Parameter getters of the link

const Dimensions &getSrcDimensions() const

Get the Dimensions for the source Output .

Return

The Dimensions for the source Output

const Dimensions &getDestDimensions() const

Get the Dimensions for the destination Input .

Return

The Dimensions for the destination Input

const std::string &getLinkType() const

Get the type of the link.

Return

The type of the link

const std::string &getLinkParams() const

Get the parameters of the link.

Return

The parameters of the link

const std::string &getSrcRegionName() const

Get the name of the source Region.

Return

The name of the source Region

const std::string &getSrcOutputName() const

Get the name of the source Output.

Return

The name of the source Output

const std::string &getDestRegionName() const

Get the name of the destination Region.

Return

The name of the destination Region

const std::string &getDestInputName() const

Get the name of the destination Input.

Return

The name of the destination Input

Misc

Output &getSrc() const

Get the source Output of the link.

Return

The source Output of the link

Input &getDest() const

Get the destination Input of the link.

Return

The destination Input of the link

void compute()

Copy data from source to destination.

Nodes request input data from their input objects. The input objects, in turn, request links to copy data into the inputs.

Note

This method must be called on a fully initialized link(all 4 phases).

void buildSplitterMap(Input::SplitterMap &splitter)

Build a splitter map from the link.

A splitter map is a matrix that maps the full input of a region to the inputs of individual nodes within the region. A splitter map “sm” is declared as:

vector< vector<size_t> > sm;

sm.length() == number of nodes

Parameters

• splitter: The built SplitterMap

sm[i] is a “sparse vector” used to gather the input for node i. sm[i].size() is the size (in elements) of the input for node i.

sm[i] gathers the inputs as follows:

T *regionInput; // input buffer for the whole region
T *nodeInput; // pre-allocated
for (size_t elem = 0; elem < sm[i].size; elem++)
   nodeInput[elem] = regionInput[sm[i][elem]];

The offset specified by sm[i][j] is in units of elements. To get byte offsets, you’d multiply by the size of an input/output element.

An input to a region may come from several links. Each link contributes a contiguous block of the region input starting from a certain offset. The splitter map indices are with respect to the full region input, not the partial region input contributed by this link, so the destinationOffset for this link is included in each of the splitter map entries.

Finally, the API is designed so that each link associated with an input can contribute its portion to a full splitter map. Thus the splitter map is an input-output parameter. This method appends data to each row of the splitter map, assuming that existing data in the splitter map comes from other links.

For region-level inputs, a splitter map has just a single row.

Splitter map ownership

The splitter map is owned by the containing Input. Each Link in the input contributes a portion to the splitter map, through the buildSplitterMap method.

const std::string toString() const

Convert the Link to a human-readable string.

Return

The human-readable string describing the Link

std::ostream &operator<<(std::ostream &f, const Link &link)

Serialize the link.

Parameters

• f: The output stream being serialized to
• link: The Link being serialized

LinkPolicy

class nupic::LinkPolicy

Subclassed by nupic::UniformLinkPolicy

LinkPolicyFactory

class nupic::LinkPolicyFactory

UniformLinkPolicy

class nupic::UniformLinkPolicy

Inherits from nupic::LinkPolicy