public ProgressionValue GetValueAt(DateTime when, bool strictlyEarlier)
{
ListItemStats <DateTime, WillingnessSummary> stats = this.searchHelper.FindPreviousItem(when, strictlyEarlier);
if (stats == null)
{
return(null);
}
// get some statistics
DateTime latestDate = stats.Key;
// compute how long ago that rating was given
TimeSpan duration = when.Subtract(latestDate);
// create another date that is twice as far in the past
DateTime earlierDate = latestDate.Subtract(duration);
// add up everything that occurred between the earlier day and now
WillingnessSummary sum = this.searchHelper.CombineBetweenKeys(earlierDate, true, when, !strictlyEarlier);
double numParticipations = sum.NumUnpromptedParticipations + sum.NumPromptedParticipations;
double numSkips = sum.NumSkips;
double mean = numParticipations / (numParticipations + numSkips);
double weight = numParticipations + numSkips;
Distribution distribution = Distribution.MakeDistribution(mean, 0, weight);
ProgressionValue result = new ProgressionValue(when, distribution);
return(result);
}
public WillingnessSummary Combine(WillingnessSummary a, WillingnessSummary b)
{
this.numAdditions++;
WillingnessSummary result = a.Plus(b);
return(result);
}
public WillingnessSummary Minus(WillingnessSummary other)
{
WillingnessSummary difference = new WillingnessSummary();
difference.numUnpromptedParticipations = this.numUnpromptedParticipations - other.numUnpromptedParticipations;
difference.numPromptedParticipations = this.numPromptedParticipations - other.numPromptedParticipations;
difference.numSkips = this.numSkips - other.numSkips;
return(difference);
}
public WillingnessSummary Plus(WillingnessSummary other)
{
WillingnessSummary sum = new WillingnessSummary();
sum.numUnpromptedParticipations = this.numUnpromptedParticipations + other.numUnpromptedParticipations;
sum.numPromptedParticipations = this.numPromptedParticipations + other.numPromptedParticipations;
sum.numSkips = this.numSkips + other.numSkips;
return(sum);
}
public void AddValue(DateTime when, WillingnessSummary value)
{
this.searchHelper.Add(when, value);
}
public void AddSkip(ActivitySkip newSkip)
{
WillingnessSummary willingness = WillingnessSummary.Skipped;
this.AddValue(newSkip.SuggestionStartDate, willingness);
}