data(mtcars)
mtcars
is.matrix(mtcars)
is.data.frame(mtcars)
dim(mtcars)
length(mtcars)
 
df <- data.frame(peso=c(60, 23, 45, 76, 32), sexo=c("M", "M", "F", "F", "M"))
df
is.numeric(df[,1])
is.numeric(df[,2])
dim(df)
dimnames(df)
names(df)
df$peso
df$sexo
df$p
 
 
df1 <- data.frame(peso=c(60, 23, 45, 76, 32), sexo=c("M", "M", "F", "F"))
df1 <- data.frame(peso=c(60, 23, 45, 76, 32), sexo=c("M", "M", "F", "F", NA))
df1
 
df1[5,2] <- "M"
df1
df1[5,2] <- NA
df1
df1$sexo[5] <- "M"
df1
 
cidades <- factor(c("Curitiba", "S.J.Pinhais"),levels=c("Curitiba", "S.J.Pinhais","Campo Largo"))
cidades
length(cidades)
 
summary(df$peso)
summary(df$sexo)
summary(df)
 
peso
attach(df,pos=3)
peso
peso <- 1:10
peso
df$peso
peso
rm(peso)
peso
search()
detach(2)
peso
 
 
is.data.frame(df)
is.list(df)
 
ll <- list(obj1 = 1:10, copm2 = matrix(1:12, nc=4), outro = df)
ll
 
 
mean(ll$copm2)
with(ll, mean(copm2))
 
names(ll)
length(ll)
 
ll1 <- list(1:10, matrix(1:12, nc=4), df)
ll1
 
ll$obj1
ll[[1]]
ll[1]
 
class(ll[[1]])
is.vector(ll[[1]])
is.list(ll[[1]])
 
class(ll[1])
is.vector(ll[1])
is.list(ll[1])
 
ll[c(1,3)]
ll[[c(1,3)]]