sokal_sneath_2_binary_distance#

skfp.distances.sokal_sneath_2_binary_distance(vec_a: ndarray | csr_array, vec_b: ndarray | csr_array) → float#

Sokal-Sneath distance 2 for vectors of binary values.

Computes the Sokal-Sneath distance 2 [1] [2] [3] for binary data between two input arrays or sparse matrices by subtracting the similarity from 1, using the formula:

\[dist(a, b) = 1 - sim(a, b)\]

See also sokal_sneath_2_binary_similarity(). The calculated similarity falls within the range \([0, 1]\). Passing all-zero vectors to this function results in a similarity of 1.

Parameters:

  • vec_a ({ndarray, sparse matrix}) – First binary input array or sparse matrix.

  • vec_b ({ndarray, sparse matrix}) – Second binary input array or sparse matrix.

Returns:

distance – Sokal-Sneath distance 2 between vec_a and vec_b.

Return type:

float

References

Examples

>>> from skfp.distances import sokal_sneath_2_binary_distance
>>> import numpy as np
>>> vec_a = np.array([1, 1, 1, 1])
>>> vec_b = np.array([1, 1, 0, 0])
>>> dist = sokal_sneath_2_binary_distance(vec_a, vec_b)
>>> dist
0.6666666666666667

>>> from scipy.sparse import csr_array
>>> vec_a = csr_array([[1, 1, 1, 1]])
>>> vec_b = csr_array([[1, 1, 0, 0]])
>>> dist = sokal_sneath_2_binary_distance(vec_a, vec_b)
>>> dist
0.6666666666666667