Name

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      MEDSMOOTH

Purpose

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      Median smoothing of a vector, including points near its ends.

Calling Sequence

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      SMOOTHED = MEDSMOOTH( VECTOR, WINDOW_WIDTH )

Inputs

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      VECTOR = The (1-d numeric) vector to be smoothed
      WINDOW = Odd integer giving the full width of the window over which
              the median is determined for each point. (If WINDOW is
              specified as an even number, then the effect is the same as
              using WINDOW+1)

Output

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      Function returns the smoothed vector

Procedure

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      Each point is replaced by the median of the nearest WINDOW of points.
      The width of the window shrinks towards the ends of the vector, so that
      only the first and last points are not filtered. These points are
      replaced by forecasting from smoothed interior points.

Example

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      Create a vector with isolated high points near its ends
      IDL> a = randomn(seed,40) & a[1] = 10 & a[38] = 10
      Now do median smoothing with a 7 point window
      IDL> b = medsmooth(a,7)
      Note that, unlike MEDIAN(), that MEDSMOOTH will remove the isolated
      high points near the ends.

Revision History

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      Written, H. Freudenreich, STX, 12/89
      H.Freudenreich, 8/90: took care of end-points by shrinking window.
      Speed up using vector median when possible W. Landsman February 2002