private string Sample(int targetLength, string prime = null)
{
Variable inputVariable = Model.Arguments[0];
Variable outputVariable = Model.Output;
var inputs = new Arguments();
var outputs = new Arguments();
// uses a random recommended char if no prime is provided
if (string.IsNullOrEmpty(prime))
{
prime = Vocab.GetRandomSamplePrefix.ToString();
}
var sequence = new List <float>(Vocab.CharCount * targetLength);
char[] result = new char[targetLength];
// load the prefix into the sample
int i = 0, charIndex = 0;
for (; i < prime.Length; i++)
{
charIndex = Vocab.Encode(prime[i]);
UpdateAndEvaluateModel();
result[i] = prime[i];
}
// fill the remainder of the sample with suggested chars
for (; i < targetLength; i++)
{
var outputData = outputs[outputVariable].GetDenseData <float>(outputVariable)[0] as List <float>;
charIndex = GetSuggestedIndex(outputData, i);
UpdateAndEvaluateModel();
// add the suggest char to the result string
result[i] = Vocab.Decode(charIndex);
}
void UpdateAndEvaluateModel()
{
// map the used char to the sequence
// - using a List decreases the round trip times
float[] input = new float[Vocab.CharCount];
input[charIndex] = 1;
sequence.AddRange(input);
// re-evaluate the model
inputs[inputVariable] = Value.CreateSequence(inputVariable.Shape, sequence, Device);
outputs[outputVariable] = null;
Model.Evaluate(inputs, outputs, Device);
}
return(new string(result));
}