Essa é uma revisão anterior do documento!

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a9 <- rep(paste("grupo", 1:5, sep="-"), each=4)
a9
 
a10 <- rep(paste(c("Tarde", "Noite"), 1:6, sep=""), each=4)
a10
 
## "Semana 3 Quarta","Semana 3 Sexta","Semana 4 Quarta","Semana 4 Sexta", 
rep("Semana", 4)
rep(3:4, each=2)
rep(c("quarta", "sexta"), 2)
 
paste(rep("Semana", 4), rep(3:4, each=2),rep(c("quarta", "sexta"), 2))
paste("Semana", rep(3:4, each=2),rep(c("quarta", "sexta"), 2))
paste("Semana", rep(3:4, each=2),c("quarta", "sexta"))
 
a12 <- rep(c("Azul", "Vermelho", "Branco"), 3)
a12
class(a12)
attributes(a12)
 
a13 <- factor(a12)
a13
class(a13)
attributes(a13)
a13[-2]
a13[-c(2,5,8)]
 
matrix(1:20, nc=5)
matrix(1:23, nc=5)
matrix(1:20, nc=6)
matrix(1:10, nc=5, nr=6)
matrix(1:10, nr=5, nc=6)
t(matrix(1:10, nr=5, nc=6))
matrix(1:10, nc=5, nr=6, byrow=TRUE)
 
m <- matrix(sample(1:20), nc=5)
m
m[3,2]
m[7]
 
m[,2]
m[,2:3]
m[c(1,3,4),c(2,4)]
m[-2,c(2,4)]
m[1:2,]
m[2,]
m[2,,drop=FALSE]
 
dim(m)
length(m)
m
apply(m,1,sum)
apply(m,2,sum)
apply(m,1,mean)
apply(m,2,mean)