Compute the qth percentile of the data along the specified axis.
Returns the qth percentile of the array elements.
Parameters :  a : array_like
q : float in range of [0,100] (or sequence of floats)
axis : int, optional
out : ndarray, optional
overwrite_input : bool, optional


Returns :  pcntile : ndarray

Notes
Given a vector V of length N, the qth percentile of V is the qth ranked value in a sorted copy of V. A weighted average of the two nearest neighbors is used if the normalized ranking does not match q exactly. The same as the median if q=50, the same as the minimum if q=0 and the same as the maximum if q=100.
Examples
>>> a = np.array([[10, 7, 4], [3, 2, 1]])
>>> a
array([[10, 7, 4],
[ 3, 2, 1]])
>>> np.percentile(a, 50)
3.5
>>> np.percentile(a, 0.5, axis=0)
array([ 6.5, 4.5, 2.5])
>>> np.percentile(a, 50, axis=1)
array([ 7., 2.])
>>> m = np.percentile(a, 50, axis=0)
>>> out = np.zeros_like(m)
>>> np.percentile(a, 50, axis=0, out=m)
array([ 6.5, 4.5, 2.5])
>>> m
array([ 6.5, 4.5, 2.5])
>>> b = a.copy()
>>> np.percentile(b, 50, axis=1, overwrite_input=True)
array([ 7., 2.])
>>> assert not np.all(a==b)
>>> b = a.copy()
>>> np.percentile(b, 50, axis=None, overwrite_input=True)
3.5