This is the spec for a tool which will allow us to "farm out" updates to certain features using a method other than ProPPR's stochastic gradient descent. The basic sketch was designed by William Cohen, William Y. Wang, and Katie Mazaitis on 8 April, 2015.

All code mentions below refer to branch externalGradientTool. Line numbers are tagged with a git version hash.

Data Types

Proposed New Class

GradientProvider (or call it whatever you want)

• defines method int[] updateGraph(ArrayLearningGraph g) which modifies g in-place and returns a list of feature IDs which should not be regularized
• defines method void updateGradient(TIntDoubleMap gradient) which modifies gradient in-place (setting the gradient of externally handled features to 0)

Arguments & Return Values

Graph: edu.cmu.ml.proppr.graph.ArrayLearningGraph

// looping through all edges with a particular label:
ArrayLearningGraph g = ...;
for (int i=0; i<g.label_feature_id.length; i++) {
    // test feature string against some condition
    if (meetsCondition( g.featureLibrary.getSymbol(g.label_feature_id[i]) )) {
        // update feature edge weight in graph
        g.label_feature_weight[i] = ...;
    }
}

Feature stoplist: int[] where indices are pulled from g.featureLibrary.getId(featureString)

Gradient: TIntDoubleMap where keys are pulled from g.featureLibrary.getId(featureString)

Communication

First round: Make corrections to graph

A worker thread running in SRW will call externalGradientTool.updateGraph(in.x.graph), retaining the returned int[] feature stoplist. (inside SRW$SgdExample():370@5531c69)

Scaffolding required (Katie todos):

• DONE SRW access to externalGradientTool
• BREADCRUMBS externalGradientTool instantiation process in ModuleConfiguration
• DRAFT Command line syntax for externalGradientTool

Second round: Make corrections to gradient

SRW will build the gradient of the parameter vector and then call externalGradientTool.updateGradient(gradient). (before SRW:330@373d20)

Scaffolding required (Katie todos):

• DONE Wipe stoplisted elements back to zero after regularization call on SRW:285