Hello,
fBasics has functions for skewness and kurtosis: Comments on these functions are welcome!
Diethelm Wuertz
# **********************************************************
kurtosis = function (x, ...) { # A function implemented by D. Wuertz
# FUNCTION:
UseMethod("kurtosis")
}
# ------------------------------------------------------------------------------
kurtosis.default = function (x, na.rm = FALSE, ...) { # A function implemented by D. Wuertz
# Description:
# Returns the value of the kurtosis of a
# distribution function. Missing values
# can be handled.
# FUNCTION:
# Warnings:
if (!is.numeric(x) && !is.complex(x) && !is.logical(x)) {
warning("argument is not numeric or logical: returning NA")
return(as.numeric(NA))}
# Remove NAs:
if (na.rm) x = x[!is.na(x)]
# Kurtosis:
n = length(x)
if (is.integer(x)) x = as.numeric(x)
kurtosis = sum((x-mean(x))^4/var(x)^2)/length(x) - 3
# Return Value:
kurtosis }
# ------------------------------------------------------------------------------
kurtosis.data.frame = function (x, ...) { # A function implemented by D. Wuertz
sapply(x, kurtosis, ...) }
# ******************************************************************************
skewness = function (x, ...) { # A function implemented by D. Wuertz
UseMethod("skewness")
}# ------------------------------------------------------------------------------
skewness.default = function (x, na.rm = FALSE, ...) { # A function implemented by D. Wuertz
# Description:
# Returns the value of the skewness of a
# distribution function. Missing values
# can be handled.
# FUNCTION:
# Warnings:
if (!is.numeric(x) && !is.complex(x) && !is.logical(x)) {
warning("argument is not numeric or logical: returning NA")
return(as.numeric(NA))}
# Remove NAs:
if (na.rm) x = x[!is.na(x)]
# Skewness:
n = length(x)
if (is.integer(x)) x = as.numeric(x)
skewness = sum((x-mean(x))^3/sqrt(var(x))^3)/length(x)
# Return Value:
skewness }
# ------------------------------------------------------------------------------
skewness.data.frame = function (x, ...) { # A function implemented by D. Wuertz
sapply(x, skewness, ...) }
Vito Ricci wrote:
Hi,
in which R-package I could find skewness and kurtosis measures for a distribution?
I built some functions:
gamma1<-function(x) { m=mean(x) n=length(x) s=sqrt(var(x)) m3=sum((x-m)^3)/n g1=m3/(s^3) return(g1) }
skewness<-function(x) { m=mean(x) me=median(x) s=sqrt(var(x)) sk=(m-me)/s return(sk) }
bowley<-function(x) { q<-as.vector(quantile(x,prob=c(.25,.50,.75))) b=(q[3]+q[1]-2*q[2])/(q[3]-q[2]) return(b) }
b3<-function(x) { m=mean(x) me=median(x) n=length(x) d=sum(abs(x-me))/n b=(m-me)/d return(b) }
but I'm looking for some already included in a package.
Thanks in advance. Best Vito
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