/// <summary>
/// Berechnet das gleitende Mittel aus einem Array von Werten.
/// </summary>
/// <returns>Enumerator mit der gleien Anzahl von Elementen wie values.</returns>
public static IEnumerable <StationValue> MovingAverage(
this IEnumerable <StationValue> values,
int windowSize)
{
var buffer = new StationValue[windowSize];
using var enumerator = values.GetEnumerator();
int i, j;
for (i = 0; i < windowSize - 1 && enumerator.MoveNext(); i++)
{
buffer[i] = enumerator.Current;
}
for (j = windowSize / 2; enumerator.MoveNext(); i = (i + 1) % 24, j = (j + 1) % 24)
{
buffer[i] = enumerator.Current;
yield return(new StationValue
{
ForecastDate = buffer[j].ForecastDate,
Parameter = "TAVG",
StationId = buffer[j].StationId,
Value = buffer.Average(s => s.Value)
});
}
}
private IEnumerable <StationValue> ReadStationValueFile(string stationId)
{
var filename = Path.Combine(_directory, stationId + ".dat");
if (!File.Exists(filename))
{
yield break;
}
using var reader = new BinaryReader(File.Open(
filename,
FileMode.Open, FileAccess.Read, FileShare.ReadWrite));
long length = reader.BaseStream.Length;
while (reader.BaseStream.Position != length)
{
yield return(StationValue.Deserialize(reader));
}
}
public static IEnumerable <StationValue> GetLocalMaxMin(this IEnumerable <StationValue> values, decimal lng)
{
double offset = (double)lng / 15;
using var enumerator = values.GetEnumerator();
StationValue?max = null, min = null;
bool hasNext = enumerator.MoveNext();
if (!hasNext)
{
yield break;
}
StationValue last = enumerator.Current;
while (hasNext)
{
StationValue current = enumerator.Current;
DateTime localDate = current.ForecastDate.AddHours(offset);
hasNext = enumerator.MoveNext();
bool dateChanged = localDate.Date != last.ForecastDate.AddHours(offset).Date;
if (!dateChanged)
{
if (current.Parameter == "TX" && current.Value.HasValue && localDate.Hour >= 12)
{
if (max == null || current.Value > max.Value)
{
max = current;
}
}
if (current.Parameter == "TN" && current.Value.HasValue && localDate.Hour < 12)
{
if (min == null || current.Value < min.Value)
{
min = current;
}
}
}
if (dateChanged || !hasNext)
{
if (max != null)
{
yield return(new StationValue
{
ForecastDate = max.ForecastDate,
Parameter = "TXLOCAL",
StationId = max.StationId,
Value = max.Value
});
max = null;
}
if (min != null)
{
yield return(new StationValue
{
ForecastDate = min.ForecastDate,
Parameter = "TNLOCAL",
StationId = min.StationId,
Value = min.Value
});
min = null;
}
}
last = current;
}
}
