a=c(3,5)
 a=as.data.frame(a)
 attributes(a1)  # evidenzia le caratteristiche dell'oggetto
 names(a)="pippo"
 names(a)
 row.names(a)=c("tizio","caio")
 row.names(a)
 b=t(a)
 aa=matrix(c(2,4,5,6),2,2)
 args(matrix)
 b=c("pippo","pluto","minnie")
 a1=seq(0,100,5)
 a2=rep(1:3,10)
 length(a2)
 nrow(aa) 
ncol(aa)
aa=runif(100) 
length(which(aa>0.9))
p.ali=scan("c:/msmf/alitalia.txt")