library(PRcalc)
data(nz_district)
nz_1949 <- nz_district |>
  subset(year == 1949) |>
  as_prcalc(l1   = "region",
            l2   = "district",
            p    = "electorates",
            q    = "magnitude",
            type = "nested")
decompose3(nz_1949, special = "Maori")alpha = 2 
alpha-divergence          Special  Reapportionment    Redistricting 
    6.037171e-02     6.536250e-03     3.606409e-06     5.383185e-02 
Note: "alha-divergence" is sum of "Special", "Reapportionment" and "Redisticting" terms.