/// <summary>
/// Computes a single-mutation neighborhood (one param at a time) for a given configuration. For
/// numeric parameters, samples K mutations (i.e., creates K neighbors based on that paramater).
/// </summary>
/// <param name="parent">Starting configuration.</param>
/// <returns>A set of configurations that each differ from parent in exactly one parameter.</returns>
private ParameterSet[] GetOneMutationNeighborhood(ParameterSet parent)
{
List <ParameterSet> neighbors = new List <ParameterSet>();
SweeperProbabilityUtils spu = new SweeperProbabilityUtils(_host);
for (int i = 0; i < _sweepParameters.Length; i++)
{
// This allows us to query possible values of this parameter.
IValueGenerator sweepParam = _sweepParameters[i];
// This holds the actual value for this parameter, chosen in this parameter set.
IParameterValue pset = parent[sweepParam.Name];
_host.AssertValue(pset);
DiscreteValueGenerator parameterDiscrete = sweepParam as DiscreteValueGenerator;
if (parameterDiscrete != null)
{
// Create one neighbor for every discrete parameter.
float[] neighbor = SweeperProbabilityUtils.ParameterSetAsFloatArray(_host, _sweepParameters, parent, false);
int hotIndex = -1;
for (int j = 0; j < parameterDiscrete.Count; j++)
{
if (parameterDiscrete[j].Equals(pset))
{
hotIndex = j;
break;
}
}
_host.Assert(hotIndex >= 0);
Random r = new Random();
int randomIndex = r.Next(0, parameterDiscrete.Count - 1);
randomIndex += randomIndex >= hotIndex ? 1 : 0;
neighbor[i] = randomIndex;
neighbors.Add(SweeperProbabilityUtils.FloatArrayAsParameterSet(_host, _sweepParameters, neighbor, false));
}
else
{
INumericValueGenerator parameterNumeric = sweepParam as INumericValueGenerator;
_host.Check(parameterNumeric != null, "SMAC sweeper can only sweep over discrete and numeric parameters");
// Create k neighbors (typically 4) for every numerical parameter.
for (int j = 0; j < _args.NumNeighborsForNumericalParams; j++)
{
float[] neigh = SweeperProbabilityUtils.ParameterSetAsFloatArray(_host, _sweepParameters, parent, false);
double newVal = spu.NormalRVs(1, neigh[i], 0.2)[0];
while (newVal <= 0.0 || newVal >= 1.0)
{
newVal = spu.NormalRVs(1, neigh[i], 0.2)[0];
}
neigh[i] = (float)newVal;
ParameterSet neighbor = SweeperProbabilityUtils.FloatArrayAsParameterSet(_host, _sweepParameters, neigh, false);
neighbors.Add(neighbor);
}
}
}
return(neighbors.ToArray());
}
/// <summary>
/// Generic parameter parser. Currently hand-hacked to auto-detect type.
///
/// Generic form: Name:Values
/// for example, lr:0.05-0.4
/// lambda:0.1-1000@log10
/// nl:2-64@log2
/// norm:-,+
/// </summary>
/// REVIEW: allow overriding auto-detection to specify type
/// and delegate to parameter type for actual parsing
/// REVIEW: specifying ordinal discrete parameters
public bool TryParseParameter(string paramValue, Type paramType, string paramName, out IValueGenerator sweepValues, out string error)
{
sweepValues = null;
error = null;
if (paramValue.Contains(','))
{
var generatorArgs = new DiscreteParamArguments();
generatorArgs.Name = paramName;
generatorArgs.Values = paramValue.Split(',');
sweepValues = new DiscreteValueGenerator(generatorArgs);
return(true);
}
// numeric parameter
if (!CmdParser.IsNumericType(paramType))
{
return(false);
}
// REVIEW: deal with negative bounds
string scaleStr = null;
int atIdx = paramValue.IndexOf('@');
if (atIdx < 0)
{
atIdx = paramValue.IndexOf(';');
}
if (atIdx >= 0)
{
scaleStr = paramValue.Substring(atIdx + 1);
paramValue = paramValue.Substring(0, atIdx);
if (scaleStr.Length < 1)
{
error = $"Could not parse sweep range for parameter: {paramName}";
return(false);
}
}
// Extract the minimum, and the maximum value of the list of suggested sweeps.
// Positive lookahead splitting at the '-' character.
// It is used for the Float and Long param types.
// Example format: "0.02-0.1;steps:5".
string[] minMaxRegex = Regex.Split(paramValue, "(?<=[^eE])-");
if (minMaxRegex.Length != 2)
{
if (minMaxRegex.Length > 2)
{
error = $"Could not parse sweep range for parameter: {paramName}";
}
return(false);
}
string minStr = minMaxRegex[0];
string maxStr = minMaxRegex[1];
int numSteps = 100;
Double stepSize = -1;
bool logBase = false;
if (scaleStr != null)
{
try
{
string[] options = scaleStr.Split(';');
bool[] optionsSpecified = new bool[3];
foreach (string option in options)
{
if (option.StartsWith("log") && !option.StartsWith("log-") && !option.StartsWith("log:-"))
{
logBase = true;
optionsSpecified[0] = true;
}
if (option.StartsWith("steps"))
{
numSteps = int.Parse(option.Substring(option.IndexOf(':') + 1));
optionsSpecified[1] = true;
}
if (option.StartsWith("inc"))
{
stepSize = Double.Parse(option.Substring(option.IndexOf(':') + 1), CultureInfo.InvariantCulture);
optionsSpecified[2] = true;
}
}
if (options.Length != optionsSpecified.Count(b => b))
{
error = $"Could not parse sweep range for parameter: {paramName}";
return(false);
}
}
catch (Exception e)
{
error = $"Error creating sweep generator for parameter '{paramName}': {e.Message}";
return(false);
}
}
if (paramType == typeof(UInt16) ||
paramType == typeof(UInt32) ||
paramType == typeof(UInt64) ||
paramType == typeof(short) ||
paramType == typeof(int) ||
paramType == typeof(long))
{
long min;
long max;
if (!long.TryParse(minStr, out min) || !long.TryParse(maxStr, out max))
{
return(false);
}
var generatorArgs = new Microsoft.ML.Sweeper.LongParamArguments();
generatorArgs.Name = paramName;
generatorArgs.Min = min;
generatorArgs.Max = max;
generatorArgs.NumSteps = numSteps;
generatorArgs.StepSize = (stepSize > 0 ? stepSize : new Nullable <Double>());
generatorArgs.LogBase = logBase;
try
{
sweepValues = new LongValueGenerator(generatorArgs);
}
catch (Exception e)
{
error = $"Error creating sweep generator for parameter '{paramName}': {e.Message}";
return(false);
}
}
else
{
Float minF;
Float maxF;
if (!Float.TryParse(minStr, out minF) || !Float.TryParse(maxStr, out maxF))
{
return(false);
}
var floatArgs = new FloatParamArguments();
floatArgs.Name = paramName;
floatArgs.Min = minF;
floatArgs.Max = maxF;
floatArgs.NumSteps = numSteps;
floatArgs.StepSize = (stepSize > 0 ? stepSize : new Nullable <Double>());
floatArgs.LogBase = logBase;
try
{
sweepValues = new FloatValueGenerator(floatArgs);
}
catch (Exception e)
{
error = $"Error creating sweep generator for parameter '{paramName}': {e.Message}";
return(false);
}
}
return(true);
}
