public void Model_Use_Case()
{
var inputShape = new int[] { 28, 28, 1 };
var numberOfClasses = 10;
var outputShape = new int[] { numberOfClasses };
(var observations, var targets) = CreateArtificialData(inputShape, outputShape, observationCount: 100);
var dataType = DataType.Float;
var device = DeviceDescriptor.UseDefaultDevice();
var random = new Random(232);
Func <CNTKDictionary> weightInit = () => Initializers.GlorotNormal(random.Next());
var biasInit = Initializers.Zero();
// Create the architecture.
var network = Layers.Input(inputShape, dataType)
.Dense(512, weightInit(), biasInit, device, dataType)
.ReLU()
.Dense(numberOfClasses, weightInit(), biasInit, device, dataType)
.Softmax();
// setup input and target variables.
var inputVariable = network.Arguments[0];
var targetVariable = Variable.InputVariable(network.Output.Shape, dataType);
// loss
var lossFunc = Losses.CategoricalCrossEntropy(network.Output, targetVariable);
var metricFunc = Metrics.Accuracy(network.Output, targetVariable);
// setup trainer.
var learner = Learners.MomentumSGD(network.Parameters());
var trainer = CNTKLib.CreateTrainer(network, lossFunc, metricFunc, new LearnerVector {
learner
});
var model = new Model(trainer, network, dataType, device);
// setup name to data.
var nameToData = new Dictionary <string, MemoryMinibatchData>
{
{ "observations", observations },
{ "targets", targets }
};
// setup name to variable
var nameToVariable = new Dictionary <string, Variable>
{
{ "observations", inputVariable },
{ "targets", targetVariable },
};
var trainSource = new MemoryMinibatchSource(nameToVariable, nameToData, seed: 232, randomize: true);
model.Fit(trainSource, batchSize: 8, epochs: 2);
(var loss, var metric) = model.Evaluate(trainSource);
Trace.WriteLine($"Final evaluation - Loss: {loss}, Metric: {metric}");
}
//[TestMethod]
public void Fitter_Loop()
{
var inputShape = new int[] { 28, 28, 1 };
var numberOfClasses = 10;
var outputShape = new int[] { numberOfClasses };
(var observations, var targets) = CreateArtificialData(inputShape, outputShape, observationCount: 10000);
var dataType = DataType.Float;
var device = DeviceDescriptor.UseDefaultDevice();
var random = new Random(232);
Func <CNTKDictionary> weightInit = () => Initializers.GlorotNormal(random.Next());
var biasInit = Initializers.Zero();
// Create the architecture.
var network = Layers.Input(inputShape, dataType)
.Dense(512, weightInit(), biasInit, device, dataType)
.ReLU()
.Dense(numberOfClasses, weightInit(), biasInit, device, dataType)
.Softmax();
// setup input and target variables.
var inputVariable = network.Arguments[0];
var targetVariable = Variable.InputVariable(network.Output.Shape, dataType);
// loss
var loss = Losses.CategoricalCrossEntropy(network.Output, targetVariable);
var metric = Metrics.Accuracy(network.Output, targetVariable);
// setup trainer.
var learner = Learners.MomentumSGD(network.Parameters());
var trainer = CNTKLib.CreateTrainer(network, loss, metric, new LearnerVector {
learner
});
// data names
var observationsName = "observations";
var targetsName = "targets";
// setup name to variable map.
var nameToVariable = new Dictionary <string, Variable>
{
{ observationsName, inputVariable },
{ targetsName, targetVariable },
};
// setup name to data map.
var nameToData = new Dictionary <string, MemoryMinibatchData>
{
{ observationsName, observations },
{ targetsName, targets }
};
var minibatchSource = new MemoryMinibatchSource(nameToVariable, nameToData, seed: 232, randomize: true);
// setup Fitter
var fitter = new Fitter(trainer, device);
// variables for training loop.
var inputMap = new Dictionary <Variable, Value>();
var epochs = 10;
int batchSize = 32;
for (int epoch = 0; epoch < epochs;)
{
var(minibatch, isSweepEnd) = minibatchSource.GetNextMinibatch(batchSize, device);
fitter.FitNextStep(minibatch, batchSize);
if (isSweepEnd)
{
var currentLoss = fitter.CurrentLoss;
var currentMetric = fitter.CurrentMetric;
fitter.ResetLossAndMetricAccumulators();
var traceOutput = $"Epoch: {epoch + 1:000} Loss = {currentLoss:F8}, Metric = {currentMetric:F8}";
++epoch;
Trace.WriteLine(traceOutput);
}
}
}
