[R] Gini coefficient in R

[Dimitris Rizopoulos]

try this version instead:

gini <- function(x, unbiased = TRUE, na.rm = FALSE){
    if (!is.numeric(x)){
        warning("'x' is not numeric; returning NA")
        return(NA)
    }
    if (!na.rm && any(na.ind <- is.na(x)))
        stop("'x' contain NAs")
    if (na.rm)
        x <- x[!na.ind]
    n <- length(x)
    mu <- mean(x)
    N <- if (unbiased) n * (n - 1) else n * n
    ox <- x[order(x)]
    dsum <- drop(crossprod(2 * 1:n - n - 1,  ox))
    dsum / (mu * N)
}

########################

gini(c(100,0,0,0))


I hope it helps.

Best,
Dimitris

----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/(0)16/336899
Fax: +32/(0)16/337015
Web: http://med.kuleuven.be/biostat/
     http://www.student.kuleuven.be/~m0390867/dimitris.htm


----- Original Message ----- 
From: "MICHELE DE MEO" <micheledemeo at gmail.com>
To: <r-help at stat.math.ethz.ch>
Sent: Monday, June 11, 2007 4:13 PM
Subject: [R] Gini coefficient in R


> If I use the Ineq library and the Gini function in this way:
>
>>Gini(c(100,0,0,0))
>
> I obtain the result 0.75 instead of 1 (that is the perfect 
> inequality).
>
> I think Gini's formula in Ineq is based on a formula as reported 
> here:
> http://mathworld.wolfram.com/GiniCoefficient.html
>
> but in the case of perfect inequality:
>
> x_1=.......=x_n-1 =0
>
> x_n>0
>
> these formula are equal to 1 - 1/n, not to 1.
>
> ....I don't know where I'm wrong....
>
>
> -- 
> Michele De Meo
> http://micheledemeo.blogspot.com/
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
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> and provide commented, minimal, self-contained, reproducible code.
> 


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