Select columns with select()

select() lets you pick which columns (variables) to use. The first argument to select() is a data frame, the subsequent arguments are columns to use.

The order you list the columns will determine the order of the columns returned by select().

# Select columns by name:
flights |> 
  select(year, month, day)

## # A tibble: 336,776 × 3
##     year month   day
##    <int> <int> <int>
##  1  2013     1     1
##  2  2013     1     1
##  3  2013     1     1
##  4  2013     1     1
##  5  2013     1     1
##  6  2013     1     1
##  7  2013     1     1
##  8  2013     1     1
##  9  2013     1     1
## 10  2013     1     1
## # ℹ 336,766 more rows

# Select all columns between year and day (inclusive):
flights |> 
  select(year:day)

## # A tibble: 336,776 × 3
##     year month   day
##    <int> <int> <int>
##  1  2013     1     1
##  2  2013     1     1
##  3  2013     1     1
##  4  2013     1     1
##  5  2013     1     1
##  6  2013     1     1
##  7  2013     1     1
##  8  2013     1     1
##  9  2013     1     1
## 10  2013     1     1
## # ℹ 336,766 more rows

# Select all columns except those from year to day (inclusive):
flights |> 
  select(!year:day)

## # A tibble: 336,776 × 16
##    dep_time sched_dep_time dep_delay arr_time sched_arr_time arr_delay carrier
##       <int>          <int>     <dbl>    <int>          <int>     <dbl> <chr>  
##  1      517            515         2      830            819        11 UA     
##  2      533            529         4      850            830        20 UA     
##  3      542            540         2      923            850        33 AA     
##  4      544            545        -1     1004           1022       -18 B6     
##  5      554            600        -6      812            837       -25 DL     
##  6      554            558        -4      740            728        12 UA     
##  7      555            600        -5      913            854        19 B6     
##  8      557            600        -3      709            723       -14 EV     
##  9      557            600        -3      838            846        -8 B6     
## 10      558            600        -2      753            745         8 AA     
## # ℹ 336,766 more rows
## # ℹ 9 more variables: flight <int>, tailnum <chr>, origin <chr>, dest <chr>,
## #   air_time <dbl>, distance <dbl>, hour <dbl>, minute <dbl>, time_hour <dttm>

# Select all columns that are characters:
flights |> 
  select(where(is.character))

## # A tibble: 336,776 × 4
##    carrier tailnum origin dest 
##    <chr>   <chr>   <chr>  <chr>
##  1 UA      N14228  EWR    IAH  
##  2 UA      N24211  LGA    IAH  
##  3 AA      N619AA  JFK    MIA  
##  4 B6      N804JB  JFK    BQN  
##  5 DL      N668DN  LGA    ATL  
##  6 UA      N39463  EWR    ORD  
##  7 B6      N516JB  EWR    FLL  
##  8 EV      N829AS  LGA    IAD  
##  9 B6      N593JB  JFK    MCO  
## 10 AA      N3ALAA  LGA    ORD  
## # ℹ 336,766 more rows

helper functions for select()

There are a number of helper functions you can use within select():

• starts_with("abc"): matches names that begin with “abc”.
• ends_with("xyz"): matches names that end with “xyz”.
• contains("ijk"): matches names that contain “ijk”.
• num_range("x", 1:3): matches x1, x2 and x3.

See ?select for more details.

You can rename variables as you select() them by using =. The new name appears on the left hand side of the =, and the old variable appears on the right hand side:

flights |> 
  select(tail_num = tailnum)

## # A tibble: 336,776 × 1
##    tail_num
##    <chr>   
##  1 N14228  
##  2 N24211  
##  3 N619AA  
##  4 N804JB  
##  5 N668DN  
##  6 N39463  
##  7 N516JB  
##  8 N829AS  
##  9 N593JB  
## 10 N3ALAA  
## # ℹ 336,766 more rows