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# numpy.median

numpy.median(a, axis=None, out=None, overwrite_input=False, keepdims=False)

  Compute the median along the specified axis.

  Returns the median of the array elements.

  Parameters:
    a array_like

      Input array or object that can be converted to an array.

    axis{int, sequence of int, None}, optional

      Axis or axes along which the medians are computed. The default, axis=None, will compute the median along a flattened version of the array. If a sequence of axes, the array is first flattened along the given axes, then the median is computed along the resulting flattened axis.

    out ndarray, optional

      Alternative output array in which to place the result. It must have the same shape and buffer length as the expected output, but the type (of the output) will be cast if necessary.

    overwrite_input bool, optional

      If True, then allow use of memory of input array a for calculations. The input array will be modified by the call to `median`. This will save memory when you do not need to preserve the contents of the input array. Treat the input as undefined, but it will probably be fully or partially sorted. Default is False. If overwrite_input is `True` and a is not already an `ndarray`, an error will be raised.

    keepdims bool, optional

      If this is set to True, the axes which are reduced are left in the result as dimensions with size one. With this option, the result will broadcast correctly against the original arr.

  Returns:
    median ndarray

      A new array holding the result. If the input contains integers or floats smaller than `float64`, then the output data-type is `np.float64`. Otherwise, the data-type of the output is the same as that of the input. If out is specified, that array is returned instead.

  See also

  `mean`, `percentile`

  Notes

  Given a vector `V` of length `N`, the median of `V` is the middle value of a sorted copy of `V`, `V_sorted` - i e., `V_sorted[(N-1)/2]`, when `N` is odd, and the average of the two middle values of `V_sorted` when `N` is even.

  Examples

      >>> import numpy as np
      >>> a = np.array([[10, 7, 4], [3, 2, 1]])
      >>> a
      array([[10,  7,  4],
             [ 3,  2,  1]])
      >>> np.median(a)
      np.float64(3.5)
      >>> np.median(a, axis=0)
      array([6.5, 4.5, 2.5])
      >>> np.median(a, axis=1)
      array([7.,  2.])
      >>> np.median(a, axis=(0, 1))
      np.float64(3.5)
      >>> m = np.median(a, axis=0)
      >>> out = np.zeros_like(m)
      >>> np.median(a, axis=0, out=m)
      array([6.5,  4.5,  2.5])
      >>> m
      array([6.5,  4.5,  2.5])
      >>> b = a.copy()
      >>> np.median(b, axis=1, overwrite_input=True)
      array([7.,  2.])
      >>> assert not np.all(a==b)
      >>> b = a.copy()
      >>> np.median(b, axis=None, overwrite_input=True)
      np.float64(3.5)
      >>> assert not np.all(a==b)