我正在使用描述here的第四阶巴特沃斯滤波器。我创建了一个按钮来过滤我的数据并在Click事件上绘制它们。除了一件事之外,它的工作原理非常好:如果我在按钮上多次单击,数据会被进一步过滤,每次给我一条“更平滑”的曲线。我不确定这是否是我想要摆脱的东西,但我想首先理解这种行为,因为我感觉输入数据没有被修改,所以这不应该发生。
这是我的按钮代码:
/// <summary>
/// Handles the Click event on the smoothExperimentDataButton button ; applies 4th order Butterworth filter to the Experiment data and plots it
/// </summary>
/// <param name="sender"></param>
/// <param name="f"></param>
private void smoothExperimentDataButton_Click(object sender, EventArgs f)
{
chart1.Series["Filtered experiment"].Points.Clear();
double Samplingrate = 1 / deltaTimeinsec;
long dF2 = ValeurPixelsSumExperiment.Length - 1;
double[] Dat2 = new double[dF2 + 4];
double[] data = ValeurPixelsSumExperiment;
// Copy input data to Dat2
for (long r = 0; r < dF2; r++)
{
Dat2[2 + r] = ValeurPixelsSumExperiment[r];
}
Dat2[1] = Dat2[0] = ValeurPixelsSumExperiment[0];
Dat2[dF2 + 3] = Dat2[dF2 + 2] = ValeurPixelsSumExperiment[dF2];
const double pi = 3.14159265358979;
double wc = Math.Tan(CutOff * pi / Samplingrate);
double k1 = 1.414213562 * wc; // Sqrt(2) * wc
double k2 = wc * wc;
double a = k2 / (1 + k1 + k2);
double b = 2 * a;
double c = a;
double k3 = b / k2;
double d = -2 * a + k3;
double e = 1 - (2 * a) - k3;
// RECURSIVE TRIGGERS - ENABLE filter is performed (first, last points constant)
double[] DatYt = new double[dF2 + 4];
DatYt[1] = DatYt[0] = ValeurPixelsSumExperiment[0];
for (long s = 2; s < dF2 + 2; s++)
{
DatYt[s] = a * Dat2[s] + b * Dat2[s - 1] + c * Dat2[s - 2] + d * DatYt[s - 1] + e * DatYt[s - 2];
}
DatYt[dF2 + 3] = DatYt[dF2 + 2] = DatYt[dF2 + 1];
// FORWARD filter
double[] DatZt = new double[dF2 + 2];
DatZt[dF2] = DatYt[dF2 + 2];
DatZt[dF2 + 1] = DatYt[dF2 + 3];
for (long t = -dF2 + 1; t <= 0; t++)
{
DatZt[-t] = a * DatYt[-t + 2] + b * DatYt[-t + 3] + c * DatYt[-t + 4] + d * DatZt[-t + 1] + e * DatZt[-t + 2];
}
// Calculated points copied for return
for (long p = 0; p < dF2; p++)
{
data[p] = DatZt[p];
}
for (int i = 1; i < 1023; i++)
{
chart1.Series["Filtered experiment"].Points.AddXY(i, data[i]);
}
chart1.Series["Experiment"].Points.Clear();
}
非常感谢!
答案 0 :(得分:0)
在这一行:
double[] data = ValeurPixelsSumExperiment;
data
将引用ValeurPixelsSumExperiment
数组,该数组似乎包含您的源数据。
所以无论你在哪里data[x] = y;
,你基本上都在做ValeurPixelsSumExperiment[x] = y;
(覆盖输入数据)
计算结束时会发生什么:
// Calculated points copied for return
for (long p = 0; p < dF2; p++)
{
data[p] = DatZt[p];
}