/// <summary>
/// 算术平均值过滤. 窗口长度内取平均值
/// </summary>
/// <param name="values">原集合</param>
/// <param name="windowLength">窗口长度</param>
/// <returns>新的样本集</returns>
public static double[] FilterWithWindowMean(this IIndexable <double> values, int windowLength)
{
windowLength.ShouldBeNotLessThanZero();
windowLength.ShouldNotLargerThan(values.Count());
var result = new double[values.Count];
int half = windowLength / 2;
for (int i = half; i < values.Count - half; i++)
{
result[i] = values.TakePythonStyle(i - half, i + half + 1)
.ToArray()
.Sum((e) => e) / windowLength;
}
return(result);
}
/// <summary>
/// 中位值过滤. 窗口长度内取中位值
/// </summary>
/// <param name="values">原集合</param>
/// <param name="windowLength">窗口长度</param>
/// <returns>新的样本集</returns>
public static double[] FilterWithWindowMedian(this IIndexable <double> values, int windowLength)
{
windowLength.ShouldLargerThan(0);
windowLength.ShouldBeOdd();
windowLength.ShouldNotLargerThan(values.Count());
var result = new double[values.Count];
int half = windowLength / 2;
for (int i = half; i < values.Count - half; i++)
{
double[] window = values.TakePythonStyle(i - half, i + half + 1).OrderBy((e) => e).ToArray();
result[i] = window[half + 1];
}
return(result);
}
