gini {GeoXp} | R Documentation |
The function `gini' calculates the Gini Index associated to the variable `var'.
gini(var)
var |
a vector of numerical values of size n |
Let $x_k$, $k=1,..,K$ be the distinct values taken by $Var$. For each site, Gini.r returns two pairs of frequencies. The pair $(f,g)$ where f represents
f_k=frac{1}{n}sum_i 1(Var_i=x_k)
($n$ is the length of `var') and g represents
g_k=frac{x_k}{bar{x}}f_k
The pair $(F,G)$ represents the corresponding cumulative frequencies.
The Gini Index is calculated as :
I_G=frac{1}{2bar{x}}sum_{i=1}^Ksum_{j=1}^K|x_i-x_j|
(f, F, g, G, gini) where f, F, g and G are vectors of size K and gini a numeric value.
This function is used in ginimap.R but it is not an interactive function.
Thomas-Agnan C., Aragon Y., Ruiz-Gazen A., Laurent T., Robidou L.
Aragon Yves, Perrin Olivier, Ruiz-Gazen Anne, Thomas-Agnan Christine (2008), ``Statistique et Econométrie pour données géoréférencées : modèles et études de cas''