隨機平滑圖

Question

我想在下面的圖片上顯示與圖形類似的圖形。我想實現類似於cos/sin的圖形，但是有一點隨機性。圖表不應超過（100）或低於（0）限制。 沒有隨機性，我們可以寫函數是這樣的：

f(x)=cos(x)*50+50 

我正在尋找任何語言實現，或只是一個簡單的解釋。

Answer 1

你可以簡單地將幾個sin/cos與隨機係數和週期相​​加。

實現的例子：

internal struct SineWave 
{ 
    internal readonly double Amplitude; 
    internal readonly double OrdinaryFrequency; 
    internal readonly double AngularFrequency; 
    internal readonly double Phase; 
    internal readonly double ShiftY; 

    internal SineWave(double amplitude, double ordinaryFrequency, double phase, double shiftY) 
    { 
     Amplitude = amplitude; 
     OrdinaryFrequency = ordinaryFrequency; 
     AngularFrequency = 2 * Math.PI * ordinaryFrequency; 
     Phase = phase; 
     ShiftY = shiftY; 
    } 
} 

public class RandomCurve 
{ 
    private SineWave[] m_sineWaves; 

    public RandomCurve(int components, double minY, double maxY, double flatness) 
    { 
     m_sineWaves = new SineWave[components]; 

     double totalPeakToPeakAmplitude = maxY - minY; 
     double averagePeakToPeakAmplitude = totalPeakToPeakAmplitude/components; 

     int prime = 1; 
     Random r = new Random(); 
     for (int i = 0; i < components; i++) 
     { 
      // from 0.5 to 1.5 of averagePeakToPeakAmplitude 
      double peakToPeakAmplitude = averagePeakToPeakAmplitude * (r.NextDouble() + 0.5d); 

      // peak amplitude is a hald of peak-to-peak amplitude 
      double amplitude = peakToPeakAmplitude/2d; 

      // period should be a multiple of the prime number to avoid regularities 
      prime = Utils.GetNextPrime(prime); 
      double period = flatness * prime; 

      // ordinary frequency is reciprocal of period 
      double ordinaryFrequency = 1d/period; 

      // random phase 
      double phase = 2 * Math.PI * (r.NextDouble() + 0.5d); 

      // shiftY is the same as amplitude 
      double shiftY = amplitude; 

      m_sineWaves[i] = 
       new SineWave(amplitude, ordinaryFrequency, phase, shiftY); 
     } 
    } 

    public double GetY(double x) 
    { 
     double y = 0; 
     for (int i = 0; i < m_sineWaves.Length; i++) 
      y += m_sineWaves[i].Amplitude * Math.Sin(m_sineWaves[i].AngularFrequency * x + m_sineWaves[i].Phase) + m_sineWaves[i].ShiftY; 

     return y; 
    } 
} 

internal static class Utils 
{ 
    internal static int GetNextPrime(int i) 
    { 
     int nextPrime = i + 1; 
     for (; !IsPrime(nextPrime); nextPrime++) ; 
     return nextPrime; 
    } 

    private static bool IsPrime(int number) 
    { 
     if (number == 1) return false; 
     if (number == 2) return true; 

     for (int i = 2; i < number; ++i) 
      if (number % i == 0) return false; 

     return true; 
    } 
} 

Answer 2

爲了您的功能，你可以使用Math類和Cos()方法。

public static double GetCosFunction(double d) 
{ 
    return Math.Cos(d) * 50 + 50; 
} 

對於圖形解決方案，您可以檢查這些主題;

• http://www.smokycogs.com/blog/a-mathematical-graphing-application-in-c-sharp/
• http://www.codeproject.com/Articles/32836/A-simple-C-library-for-graph-plotting
• http://www.c-sharpcorner.com/tags/Math-Graph-in-C%23

Answer 3

因此，這裏是C＃編寫的代碼，它可以與隨機輸入值是隨機的多。 我只是給你一些輸出值，看看你是否可以。 Amplite可以修改餘弦值和正弦值。最後加上偏移量（因此最小值始終爲0），並且縮放比例可以確保最大值爲100.正如您所看到的，可以將噪聲添加到（圖3，圖4）。

terr1：RandomTerrarain（1000，4，1，10，5，0）; Figure 1

terr2：RandomTerrarain（1000，2,3，-10，5，0）; Figure 2

希望這有助於！

 private static Random rnd = new Random(); 
    private double[] RandomTerrarain(int length, int sinuses, int cosinuses, double amplsin, double amplcos, double noise) 
    { 
     if (length <= 0) 
      throw new ArgumentOutOfRangeException("length", length, "Length must be greater than zero!"); 
     double[] returnValues = new double[length]; 

     for (int i = 0; i < length; i++) 
     { 
      // sin 
      for (int sin = 1; sin <= sinuses; sin++) 
      { 
       returnValues[i] += amplsin * Math.Sin((2 * sin * i * Math.PI)/(double)length); 
      } 
      // cos 
      for (int cos = 1; cos <= cosinuses; cos++) 
      { 
       returnValues[i] += amplcos * Math.Cos((2 * cos * i * Math.PI)/(double)length); 
      } 
      // noise 
      returnValues[i] += (noise * rnd.NextDouble()) - (noise * rnd.NextDouble()); 
     } 
     // give offset so it be higher than 0 
     double ofs = returnValues.Min(); 
     if (ofs < 0) 
     { 
      ofs *= -1; 
      for (int i = 0; i < length; i++) 
      { 
       returnValues[i] += ofs; 
      } 
     } 
     // resize to be fit in 100 
     double max = returnValues.Max(); 
     if (max >= 100) 
     { 
      double scaler = max/100.0; 
      for (int i = 0; i < length; i++) 
      { 
       returnValues[i] /= scaler; 
      } 
     } 
     return returnValues; 
    } 

Answer 4

忘記這個....

terr3：RandomTerrarain（1000，5,5，-2，5,2）; Figure 3

terr4：RandomTerrarain（1000，4，1，5，-20，1）; Figure 4

Answer 5

看一看xkcd-style graphs，方法隨機噪聲添加到圖和平滑它的方式，使它看起來手繪，模仿xkcd cartoons的風格。雖然這不完全是你想要的，但我想簡單地將輸入圖設置爲零（例如，y = 0）並且將噪聲平滑參數調整爲更大的噪聲幅度，並且更大的平滑距離可能導致隨機圖你正在尋找。