Finding Local Maxima Over a Dynamic Range

Question

Working in C#, I need to find all local peaks in a List of doubles and return them as another List doubles. This seems simple enough if I have a set number of values I\'m co

Answer 1

I suggest a few changes to Levy's post...

1) Levy's code threw an exception when the specified values IList was a nearly straight line.

2) I think the index of the peaks in the array is the desired result. Consider for example what would happen if we had two peaks with identical doubles? Ops. Changed to return index of peaks in specified IList.

    public static IList FindPeaks(IList values, int rangeOfPeaks)
    {
        List peaks = new List();
        double current;
        IEnumerable range;

        int checksOnEachSide = rangeOfPeaks / 2;
        for (int i = 0; i < values.Count; i++)
        {
            current = values[i];
            range = values;

            if (i > checksOnEachSide)
            {
                range = range.Skip(i - checksOnEachSide);
            }

            range = range.Take(rangeOfPeaks);
            if ((range.Count() > 0) && (current == range.Max()))
            {
                peaks.Add(i);
            }
        }

        return peaks;
    }