public static ConstructGen<double> DoScaleWeights(ConstructGen<double> wts_, TraderArgs args_, Func<DateTime,double> getVolTargetForDate_)
{
if (wts_.ColumnHeadings == null)
wts_.ColumnHeadings = args_.Products.Select(x => x.Name).ToArray();
var logReturns = args_.AllProductPrices(fillInGapsWithPrevious_: true).ToLogReturns(
args_.Products.Select(x => x.Convention).ToArray());
var scaledWts = new ConstructGen<double>(wts_.ColumnHeadings);
foreach (var date in wts_.Dates)
{
var wtArr = wts_.GetValues(date);
for (int i = 0; i < wtArr.Length; ++i)
if (double.IsInfinity(wtArr[i]))
wtArr[i] = 0d;
int indexOfDate = logReturns.FindIndexOfEffectiveDateOnDate(date);
indexOfDate = (indexOfDate < 252) ? 252 : indexOfDate - 1; // note offset
var subValues = logReturns.GetSubValues(logReturns.Dates[indexOfDate - 251], logReturns.Dates[indexOfDate]);
var covArr = SI.Data.FXHistCovar.MatCovar(subValues.ToArray());
var cov = new CovarianceItem(covArr);
scaledWts.SetValues(date, cov.ScaleSeries(wtArr, getVolTargetForDate_(date)));
}
return scaledWts;
}
public static double[] weightFX(double[] input_, CovarianceItem covar_, TraderArgs args_,double targetVol_)
{
double[] scaleThis = new double[covar_.ComponentIds.Count];
int[] indices = new int[input_.Length];
for (int i = 0; i < args_.Products.Count; ++i)
{
indices[i] = covar_.ComponentIds.IndexOf(((ProductFX)args_.Products[i]).CoreProduct.ID);
scaleThis[indices[i]] = input_[i];
}
double[] scaled = covar_.ScaleSeries(scaleThis, targetVol_,args_.ScaleUsingDiagMatrix);
// contrains weights?
if (args_.WtConstraints != null && args_.WtConstraints.Enabled)
{
bool cont = true;
int iterationCount = 0;
double tolerance = 0.05; // 5% tolerance on constraint
int iterationMax = 100;
while (cont && iterationCount < iterationMax)
{
cont = false;
double upperLimit = args_.WtConstraints.UpperConstraint + Math.Abs(args_.WtConstraints.UpperConstraint * tolerance);
double lowerLimit = args_.WtConstraints.LowerConstraint - Math.Abs(args_.WtConstraints.LowerConstraint * tolerance);
for (int i = 0; i < scaled.Length; ++i)
{
if (scaled[i] < lowerLimit)
{
scaled[i] = args_.WtConstraints.LowerConstraint;
}
if (scaled[i] > upperLimit)
{
scaled[i] = args_.WtConstraints.UpperConstraint;
}
}
if (args_.WtConstraints.ReScale)
{
scaled = covar_.ScaleSeries(scaled, targetVol_);
cont = true;
}
++iterationCount;
}
}
// reshape into length of input products...
double[] ret = new double[input_.Length];
for (int i = 0; i < input_.Length; ++i)
ret[i] = scaled[indices[i]];
return ret;
}
public void Go()
{
var allweights=new ConstructGen<WeightsLine>(Spreads.Length);
// mark each of the individual spread weight entry/exit points in the construct - could well be different dates per spread...
for(int i=0;i<Spreads.Length;++i)
{
var wts = Spreads[i].GenerateWeights();
foreach (var wt in wts)
{
if (wt.EntryDate <= DateTime.Today) allweights.SetValue(wt.EntryDate, i, wt);
if (wt.ExitDate <= DateTime.Today) allweights.SetValue(wt.ExitDate, i, wt);
}
}
allweights.SortKeys();
// on each date, note the positions that are carried over from an earlier trade on the same day, so that we have a
// full picture of what is in play on that day
WeightsLine[] prev = null;
foreach (var date in allweights.Dates)
{
var todays = allweights.GetValues(date);
if (prev != null)
{
for (int i = 0; i < todays.Length; ++i)
{
if (prev[i] != null && todays[i]==null && date <= prev[i].ExitDate)
todays[i] = prev[i];
}
}
prev = todays;
}
if (allweights.NeedsToSortKeys()) allweights.SortKeys();
// go through each of the dates to generate a covariance and scale the positions
foreach (DateTime date in allweights.Keys)
{
var arr = allweights.GetValues(date);
// build up list of indicies that are live on the current date
var liveIndicies = new List<int>();
for (int i = 0; i < arr.Length; ++i)
if (arr[i] != null && arr[i].ExitDate > date)
liveIndicies.Add(i);
if (!liveIndicies.Any()) continue;
var liveItems = liveIndicies.Select(x => arr[x]).ToArray();
// for all live items form an array of recent returns over of length 'NumDaysForCovariance'
var returns = new double[NumDaysForCovariance, liveIndicies.Count()];
var rawSpreadWeights = new double[liveIndicies.Count()];
for (int i = 0; i < liveIndicies.Count; ++i)
{
var indexReturns = liveItems[i].GetAllSpreadReturns();
// have prices been updated?
if (indexReturns.LastDate < date)
continue;
int indexOfDate = indexReturns.IndexOfElsePrevious(date);
--indexOfDate;
var slice = indexReturns.Data.Slice(indexOfDate - NumDaysForCovariance + 1, NumDaysForCovariance);
rawSpreadWeights[i] = liveItems[i].SpreadWeight/Statistics.Stdev(slice);
returns.SetColumn(i, slice);
}
// buil the covariance
var covar = new CovarianceItem(Utils.CalculateCovariance(returns));
// vol bucketing
var targetvol = liveItems.Length*0.02;
// scale the weights
var newwts = covar.ScaleSeries(rawSpreadWeights, targetvol);
for (int i = 0; i < newwts.Length; ++i)
liveItems[i].AddCombineWeight(date, newwts[i]);
}
}