jensenshannon(p, q, base=None, *, axis=0, keepdims=False)

The Jensen-Shannon distance between two probability vectors p and q is defined as,

$$\sqrt{\frac{D(p \parallel m) + D(q \parallel m)}{2}}$$

where $m$ is the pointwise mean of $p$ and $q$ and $D$ is the Kullback-Leibler divergence.

This routine will normalize p and q if they don't sum to 1.0.

Notes

Parameters

p : (N,) array_like

left probability vector

q : (N,) array_like

right probability vector

base : double, optional

the base of the logarithm used to compute the output if not given, then the routine uses the default base of scipy.stats.entropy.

axis : int, optional

Axis along which the Jensen-Shannon distances are computed. The default is 0.

versionadded

keepdims : bool, optional

If this is set to :None:None:`True`, the reduced axes are left in the result as dimensions with size one. With this option, the result will broadcast correctly against the input array. Default is False.

versionadded

Returns

js : double or ndarray

The Jensen-Shannon distances between p and q along the :None:None:`axis`.

Compute the Jensen-Shannon distance (metric) between two probability arrays. This is the square root of the Jensen-Shannon divergence.

Examples

>>> from scipy.spatial import distance
... distance.jensenshannon([1.0, 0.0, 0.0], [0.0, 1.0, 0.0], 2.0)
1.0

>>> distance.jensenshannon([1.0, 0.0], [0.5, 0.5])
0.46450140402245893

>>> distance.jensenshannon([1.0, 0.0, 0.0], [1.0, 0.0, 0.0])
0.0

>>> a = np.array([[1, 2, 3, 4],
...               [5, 6, 7, 8],
...               [9, 10, 11, 12]])
... b = np.array([[13, 14, 15, 16],
...               [17, 18, 19, 20],
...               [21, 22, 23, 24]])
... distance.jensenshannon(a, b, axis=0)
array([0.1954288, 0.1447697, 0.1138377, 0.0927636])

>>> distance.jensenshannon(a, b, axis=1)
array([0.1402339, 0.0399106, 0.0201815])

See :

Back References

The following pages refer to to this document either explicitly or contain code examples using this.

scipy.spatial.distance.jensenshannon

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