Matrix oriented computing
On Fri, 2005-08-26 at 14:44 +0200, Sigbert Klinke wrote:
Hi,
I want to compute the quantiles of Chi^2 distributions with different
degrees of freedom like
x<-cbind(0.005, 0.010, 0.025, 0.05, 0.1, 0.5, 0.9, 0.95, 0.975, 0.99, 0.995)
df<-rbind(1:100)
m<-qchisq(x,df)
and hoped to get back a length(df) times length(x) matrix with the
quantiles. Since this does not work, I use
x<-c(0.005, 0.010, 0.025, 0.05, 0.1, 0.5, 0.9, 0.95, 0.975, 0.99, 0.995)
df<-c(1:100)
m<-qchisq(x,df[1])
for (i in 2:length(df)) {
m<-rbind(m,qchisq(x,df[i]))
}
dim(m)<-c(length(df),length(x))
Is there a way to avoid the for loop ?
Thanks Sigbert
See ?sapply
x <- c(0.005, 0.010, 0.025, 0.05, 0.1, 0.5, 0.9,
0.95, 0.975, 0.99, 0.995)
df <- c(1:100)
mat <- sapply(x, qchisq, df)
dim(mat)
[1] 100 11
str(mat)
num [1:100, 1:11] 3.93e-05 1.00e-02 7.17e-02 2.07e-01 4.12e-01 ... HTH, Marc Schwartz