Rmarkdown Report 3

P.150

1

library(ggplot2)
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 %>%
  group_by(class) %>%
  summarise(mean_cty = mean(cty))

## # A tibble: 7 × 2
##   class      mean_cty
##   <chr>         <dbl>
## 1 2seater        15.4
## 2 compact        20.1
## 3 midsize        18.8
## 4 minivan        15.8
## 5 pickup         13  
## 6 subcompact     20.4
## 7 suv            13.5

2

mpg %>%
  group_by(class) %>%
  summarise(mean_cty = mean(cty)) %>%
  arrange(desc(mean_cty))

## # A tibble: 7 × 2
##   class      mean_cty
##   <chr>         <dbl>
## 1 subcompact     20.4
## 2 compact        20.1
## 3 midsize        18.8
## 4 minivan        15.8
## 5 2seater        15.4
## 6 suv            13.5
## 7 pickup         13

3

mpg %>%
  group_by(manufacturer) %>%
  summarise(mean_hwy = mean(hwy)) %>%
  arrange(desc(mean_hwy)) %>%
  head(3)

## # A tibble: 3 × 2
##   manufacturer mean_hwy
##   <chr>           <dbl>
## 1 honda            32.6
## 2 volkswagen       29.2
## 3 hyundai          26.9

4

mpg %>%
  filter(class == "compact") %>%
  group_by(manufacturer) %>%
  summarise(count = n()) %>%
  arrange(desc(count))

## # A tibble: 5 × 2
##   manufacturer count
##   <chr>        <int>
## 1 audi            15
## 2 volkswagen      14
## 3 toyota          12
## 4 subaru           4
## 5 nissan           2

P.156-157

1

fuel <- data.frame(fl = c("c", "d", "e", "p", "r"),
                      price_fl = c(2.35, 2.38, 2.11, 2.76, 2.22),
                      stringsAsFactors = F)
fuel

##   fl price_fl
## 1  c     2.35
## 2  d     2.38
## 3  e     2.11
## 4  p     2.76
## 5  r     2.22

mpg <- as.data.frame(ggplot2::mpg)
mpg <- left_join(mpg, fuel, by ="fl")

2

mpg %>%
  select(model, fl, price_fl) %>%
  head(5)

##   model fl price_fl
## 1    a4  p     2.76
## 2    a4  p     2.76
## 3    a4  p     2.76
## 4    a4  p     2.76
## 5    a4  p     2.76