private void TrainingStats(EvalParameters evalParams)
{
var numCorrect = 0;
for (var ei = 0; ei < numUniqueEvents; ei++)
{
for (var ni = 0; ni < numTimesEventsSeen[ei]; ni++)
{
var modelDistribution = new double[numOutcomes];
PerceptronModel.Eval(
contexts[ei],
values?[ei],
modelDistribution,
evalParams,
false);
var max = MaxIndex(modelDistribution);
if (max == outcomeList[ei])
{
numCorrect++;
}
}
}
var trainingAccuracy = (double)numCorrect / numEvents;
info.Append(" Correct Events: {0}\n" +
" Total Events: {1}\n" +
" Accuracy: {2}\n", numCorrect, numEvents, trainingAccuracy);
Display("\nPerceptron training complete:\n");
Display("\t Correct Events : " + numCorrect);
Display("\t Total Events : " + numEvents);
Display("\t Accuracy : " + trainingAccuracy);
}
private MutableContext[] FindParameters(int iterations, bool useAverage)
{
info.Append(" Number of Iterations: {0}\n", iterations);
Display("\nPerforming " + iterations + " iterations.\n");
var allOutcomesPattern = new int[numOutcomes];
for (var oi = 0; oi < numOutcomes; oi++)
{
allOutcomesPattern[oi] = oi;
}
/* Stores the estimated parameter value of each predicate during iteration. */
var param = new MutableContext[numPreds];
for (var pi = 0; pi < numPreds; pi++)
{
param[pi] = new MutableContext(allOutcomesPattern, new double[numOutcomes]);
for (var aoi = 0; aoi < numOutcomes; aoi++)
{
param[pi].SetParameter(aoi, 0.0);
}
}
// ReSharper disable once CoVariantArrayConversion
var evalParams = new EvalParameters(param, numOutcomes);
// Stores the sum of parameter values of each predicate over many iterations.
var summedParams = new MutableContext[numPreds];
if (useAverage)
{
for (var pi = 0; pi < numPreds; pi++)
{
summedParams[pi] = new MutableContext(allOutcomesPattern, new double[numOutcomes]);
for (var aoi = 0; aoi < numOutcomes; aoi++)
{
summedParams[pi].SetParameter(aoi, 0.0);
}
}
}
// Keep track of the previous three accuracies. The difference of
// the mean of these and the current training set accuracy is used
// with tolerance to decide whether to stop.
var prevAccuracy1 = 0.0;
var prevAccuracy2 = 0.0;
var prevAccuracy3 = 0.0;
// A counter for the denominator for averaging.
var numTimesSummed = 0;
double stepSize = 1;
for (var i = 1; i <= iterations; i++)
{
// Decrease the step size by a small amount.
if (stepSizeDecrease > 0)
{
stepSize *= 1 - stepSizeDecrease;
}
if (Monitor != null && Monitor.Token.CanBeCanceled)
{
Monitor.Token.ThrowIfCancellationRequested();
}
var numCorrect = 0;
for (var ei = 0; ei < numUniqueEvents; ei++)
{
var targetOutcome = outcomeList[ei];
for (var ni = 0; ni < numTimesEventsSeen[ei]; ni++)
{
// Compute the model's prediction according to the current parameters.
var modelDistribution = new double[numOutcomes];
PerceptronModel.Eval(
contexts[ei],
values != null ? values[ei] : null,
modelDistribution,
evalParams, false);
var maxOutcome = MaxIndex(modelDistribution);
// If the predicted outcome is different from the target
// outcome, do the standard update: boost the parameters
// associated with the target and reduce those associated
// with the incorrect predicted outcome.
if (maxOutcome != targetOutcome)
{
for (var ci = 0; ci < contexts[ei].Length; ci++)
{
var pi = contexts[ei][ci];
if (values == null)
{
param[pi].UpdateParameter(targetOutcome, stepSize);
param[pi].UpdateParameter(maxOutcome, -stepSize);
}
else
{
param[pi].UpdateParameter(targetOutcome, stepSize * values[ei][ci]);
param[pi].UpdateParameter(maxOutcome, -stepSize * values[ei][ci]);
}
}
}
// Update the counts for accuracy.
if (maxOutcome == targetOutcome)
{
numCorrect++;
}
}
}
// Calculate the training accuracy and display.
var trainingAccuracy = (double)numCorrect / numEvents;
Display($"{i,-4} {numCorrect} of {numEvents} - {trainingAccuracy}");
// TODO: Make averaging configurable !!!
bool doAveraging;
if (useAverage && UseSkippedAveraging && (i < 20 || IsPerfectSquare(i)))
{
doAveraging = true;
}
else if (useAverage)
{
doAveraging = true;
}
else
{
doAveraging = false;
}
if (doAveraging)
{
numTimesSummed++;
for (var pi = 0; pi < numPreds; pi++)
{
for (var aoi = 0; aoi < numOutcomes; aoi++)
{
summedParams[pi].UpdateParameter(aoi, param[pi].Parameters[aoi]);
}
}
}
// If the tolerance is greater than the difference between the
// current training accuracy and all of the previous three
// training accuracies, stop training.
if (Math.Abs(prevAccuracy1 - trainingAccuracy) < tolerance &&
Math.Abs(prevAccuracy2 - trainingAccuracy) < tolerance &&
Math.Abs(prevAccuracy3 - trainingAccuracy) < tolerance)
{
Display("Stopping: change in training set accuracy less than " + tolerance + "\n");
break;
}
// Update the previous training accuracies.
prevAccuracy1 = prevAccuracy2;
prevAccuracy2 = prevAccuracy3;
prevAccuracy3 = trainingAccuracy;
}
// Output the final training stats.
TrainingStats(evalParams);
if (!useAverage)
{
return(param);
}
if (numTimesSummed == 0) // Improbable but possible according to the Coverity.
{
numTimesSummed = 1;
}
// Create averaged parameters
for (var pi = 0; pi < numPreds; pi++)
{
for (var aoi = 0; aoi < numOutcomes; aoi++)
{
summedParams[pi].SetParameter(aoi, summedParams[pi].Parameters[aoi] / numTimesSummed);
}
}
return(summedParams);
}
