.. highlightlang:: us

.. index:: smooth
.. index:: moving_median

.. _moving_median:

moving_median
=============

.. us.tag  moving_median ENGLISH Interpolation New5149

The :ref:`moving_median` function calculates a moving median. 
The function operates over a moving window of values. For each window, the 
middle value found in the window is used.

This filter can be used to reduce random noise and spikes.

.. function::  rvMedian = moving_median(rvY, nNeighbor)

.. us.return

**Return Value**

*rvMedian* is the moving median. It has the same length as *rvY*.

.. us.params

**Parameters**

.. uparam:: rvY

   *rvY* is a signal.

.. uparam:: nNeighbor

   *nNeighbor* specifies the window width. 3 <= *nNeighbor* <= 1025.

.. us.example

**Example**

In the following example 5 consecutive points are sorted ascending and the 
third point is used. For a window size of 5, the first 2 point and the last 2 
points are not altered. The first calculated point in rvOut is the third
point:  ``[4,5,6,7,27] -> 6``, ``[4,6,7,8,27] -> 7``

:: 

   rvIn   = [5, 7, 6, 4, 27, 8, 4, 5]
   rvOut = moving_median(rvIn, 5)
   rvOut -> [5, 7, 6, 7, 6,  8, 4, 5]

::

   x = linspace(0, 2*PI, 1000)
   y = sin(x) + rand(1, 1000) * 0.1
   yy = moving_median(y, 11);
   h = plot(x, y);
   XYSetProps(h[3], "curve_color = 'blue'");
   h = plot(x, yy, h[2]);
   XYSetProps(h[3], "curve_color = 'red'");

.. us.history

**History**

.. list-table::
   :header-rows: 1

   * - Version
     - Description
   * - 5.14.9
     - New

.. seealso::
   :ref:`overview-mathematic`,
   :ref:`moving_average`,
   :ref:`fspline`,
   :ref:`pspline`,
   :ref:`akimaspline`,
   :ref:`sgolayfilt`

:sub:`id-244162`