data(mtcars)
#mtcars
mtcars$Model = rownames(mtcars)
rownames(mtcars) = NULL

mtcars$Brand = sapply(strsplit(mtcars$Model," "), FUN='[',n=1)

hp_brands = aggregate(
        mtcars$hp,
        by = list(mtcars$Brand),
        FUN = mean
)
hp_brands
names(hp_brands) = c('Brands','Mean_hp')
#hp_brands

# to sort the data we use order function

# sorted data in ascending order
#hp_brands[order(hp_brands$Mean_hp),]

# sorted data in descending order
#hp_brands[order(-hp_brands$Mean_hp),]
#mtcars$Model= NULL
#mtcars[order(mtcars$hp),]