Data Subsetting, Part 2 - Lab Key

In this lab you can use the interactive console to explore but please record your commands here. Remember anything you type here can be “sent” to the console with Cmd-Enter (OS-X) or Cntr-Enter (Windows/Linux) (But only in side the {r} areas).

library(dplyr)
library(tidyverse)

1. In the data set mpg, rename the column year to YEAR using rename.

mpg <- mpg %>% rename(YEAR = year)

2. Convert the column names of mpg to all upper case. Use rename_with, and the toupper command (or colnames). Save the output to Upper_mpg.

Upper_mpg <- rename_with(mpg, toupper)
head(Upper_mpg)

## # A tibble: 6 × 11
##   MANUFACTURER MODEL DISPL  YEAR   CYL TRANS      DRV     CTY   HWY FL    CLASS 
##   <chr>        <chr> <dbl> <int> <int> <chr>      <chr> <int> <int> <chr> <chr> 
## 1 audi         a4      1.8  1999     4 auto(l5)   f        18    29 p     compa…
## 2 audi         a4      1.8  1999     4 manual(m5) f        21    29 p     compa…
## 3 audi         a4      2    2008     4 manual(m6) f        20    31 p     compa…
## 4 audi         a4      2    2008     4 auto(av)   f        21    30 p     compa…
## 5 audi         a4      2.8  1999     6 auto(l5)   f        16    26 p     compa…
## 6 audi         a4      2.8  1999     6 manual(m5) f        18    26 p     compa…

3. Re-order the rows of mpg by cyl in increasing order. Use arrange(). Reassign the mpg data!

mpg <- mpg %>% arrange(cyl)

4. Create a new variable in mpg called cty2, which is equal to cty^2, using mutate().

mpg <- mpg %>% mutate(cty2 = cty^2)
head(mpg)

## # A tibble: 6 × 12
##   manufacturer model displ  YEAR   cyl trans drv     cty   hwy fl    class  cty2
##   <chr>        <chr> <dbl> <int> <int> <chr> <chr> <int> <int> <chr> <chr> <dbl>
## 1 audi         a4      1.8  1999     4 auto… f        18    29 p     comp…   324
## 2 audi         a4      1.8  1999     4 manu… f        21    29 p     comp…   441
## 3 audi         a4      2    2008     4 manu… f        20    31 p     comp…   400
## 4 audi         a4      2    2008     4 auto… f        21    30 p     comp…   441
## 5 audi         a4 q…   1.8  1999     4 manu… 4        18    26 p     comp…   324
## 6 audi         a4 q…   1.8  1999     4 auto… 4        16    25 p     comp…   256

5. Update the variable in mpg called displ to be 10 times the current value using mutate().

mpg <- mpg %>% mutate(displ = displ*10)
head(mpg)

## # A tibble: 6 × 12
##   manufacturer model displ  YEAR   cyl trans drv     cty   hwy fl    class  cty2
##   <chr>        <chr> <dbl> <int> <int> <chr> <chr> <int> <int> <chr> <chr> <dbl>
## 1 audi         a4       18  1999     4 auto… f        18    29 p     comp…   324
## 2 audi         a4       18  1999     4 manu… f        21    29 p     comp…   441
## 3 audi         a4       20  2008     4 manu… f        20    31 p     comp…   400
## 4 audi         a4       20  2008     4 auto… f        21    30 p     comp…   441
## 5 audi         a4 q…    18  1999     4 manu… 4        18    26 p     comp…   324
## 6 audi         a4 q…    18  1999     4 auto… 4        16    25 p     comp…   256