C#實現區域性峰值查詢,功能對應Matlab中的findpeaks.m

傑克.陳發表於2018-07-29
C#Matlab
原文:C#實現區域性峰值查詢,功能對應Matlab中的findpeaks.m

相關演算法的原理參考Ronny，地址：影像分析：投影曲線的波峰查詢，這裡感謝下原作者。

參照C++的程式碼實現，我用C#翻譯了下，其實原理也很簡單的，下面放相關實現程式碼：

        private double[] oneDiff(double[] data) 
        {
            double[] result = new double[data.Length - 1];
            for (int i = 0; i < result.Length; i++)
            {
                result[i] = data[i + 1] - data[i];
            }
            return result;
        }
        private int[] trendSign(double[] data)
        {
            int[] sign = new int[data.Length];
            for (int i = 0; i < sign.Length; i++)
            {
                if (data[i] > 0) sign[i] =1;
                else if (data[i] == 0) sign[i] = 0;
                else sign[i] = -1;
            }
            
            for (int i = sign.Length - 1; i >=0 ; i--)
            {
                if (sign[i] == 0 && i ==sign.Length - 1)
                {
                    sign[i] = 1;
                }
                else if (sign[i] == 0) 
                {
                    if (sign[i+1] >= 0)
                    {
                        sign[i] = 1;
                    }
                    else
                    {
                        sign[i] = -1;
                    }
                }
            }
            return sign;
        }
        private int[] getPeaksIndex(int[] diff) 
        {
            List<int> data = new List<int>();
            for (int i = 0; i != diff.Length - 1; i++)
            {
                if (diff[i+1] - diff[i] == -2)
                {
                    data.Add(i + 1);
                }
            }
            int[] result = new int[data.Count];
            for (int i = 0; i < result.Length; i++)
            {
                result[i] = data[i];
            }
            return result;//相當於原陣列的下標
        }

呼叫方法：

double[] data = {25, 8, 15, 5, 6, 10, 10, 3, 1, 20, 7};
int[] index = getPeaksIndex(trendSign(oneDiff(Constant.data)));

返回的int[]陣列內容是對應原陣列中峰值對應的索引(從0開始)

 


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