The quantitative version of the second Kulczynski index
weighted_kulczynski_second(x, y)Numeric vectors
The weighted Kulczynski distance between x and y. The
distance is undefined if the sum of x or the sum of y is
zero, in which case we return NaN.
The quantitative version of the second Kulczynski index is defined as
$$
d(x, y) = 1 - \frac{1}{2} \left (
\frac{\sum_i \min{(x_i, y_i)}}{\sum_i x_i} +
\frac{\sum_i \min{(x_i, y_i)}}{\sum_i y_i}
\right ).
$$
Relation of weighted_kulczynski_second() to other definitions:
Equivalent to vegdist() with method = "kulczynski".
Equivalent to structkulczynski in Mothur.
Equivalent to \(1 - S_{18}\) in Legendre & Legendre.