The Columns Gini index concentrates on the "relative
extent to which the destination selections of
in-migrations are spatially focused": $$G^T_R =
\frac{\sum_j \sum_{i \neq j} \sum_{g \neq i,j} | M_{ij} -
M_{gj} | }{ (2n(n-1)-1) \sum_i \sum_{j \neq i} M_{ij}}$$
This implementation solves the above formula by computing
the dist matrix for each columns.
Usage
migration.gini.col(m)
Arguments
m
migration matrix
Value
A number between 0 and 1 where 0 means no spatial
focusing and 1 shows maximum focusing.
References
David A. Plane and Gordon F. Mulligan
(1997) Measuring Spatial Focusing in a Migration System.
Demography34, 251--262