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numpy.ma.median(a, axis=None, out=None, overwrite_input=False)
[source] -
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, optional
Axis along which the medians are computed. The default (None) is to compute the median along a flattened version of the array.
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 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. Note that, if
overwrite_input
is True, and the input is not already anndarray
, an error will be raised.Returns: median : ndarray
A new array holding the result is returned unless out is specified, in which case a reference to out is returned. Return data-type is
float64
for integers and floats smaller thanfloat64
, or the input data-type, otherwise.See also
Notes
Given a vector
V
withN
non masked values, the median ofV
is the middle value of a sorted copy ofV
(Vs
) - i.e.Vs[(N-1)/2]
, whenN
is odd, or{Vs[N/2 - 1] + Vs[N/2]}/2
whenN
is even.Examples
>>> x = np.ma.array(np.arange(8), mask=[0]*4 + [1]*4) >>> np.ma.median(x) 1.5
>>> x = np.ma.array(np.arange(10).reshape(2, 5), mask=[0]*6 + [1]*4) >>> np.ma.median(x) 2.5 >>> np.ma.median(x, axis=-1, overwrite_input=True) masked_array(data = [ 2. 5.], mask = False, fill_value = 1e+20)
numpy.ma.median()
2017-01-10 18:15:41
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