homework

혼자서 해보기 1번

library(dplyr)

## 
## 다음의 패키지를 부착합니다: 'dplyr'

## The following objects are masked from 'package:stats':
## 
##     filter, lag

## The following objects are masked from 'package:base':
## 
##     intersect, setdiff, setequal, union

mpg <- as.data.frame(ggplot2::mpg)
mpg_a <- mpg %>% filter(displ <= 4)
mpg_b <- mpg %>% filter(displ >= 5)
mean(mpg_a$hwy)

## [1] 25.96319

mean(mpg_b$hwy)

## [1] 18.07895

혼자서 해보기 2번

mpg_audi<- mpg %>% filter(manufacturer == "audi") 
mpg_toyota <- mpg %>% filter(manufacturer == "toyota")
mean(mpg_audi$cty)

## [1] 17.61111

mean(mpg_toyota$cty)

## [1] 18.52941

혼자서 해보기 3번

mpg_new<-mpg %>% filter(manufacturer %in% c("chevrolet", "ford", "honda"))
mean(mpg_new$hwy)

## [1] 22.50943