Tidy data

Pivoting

long to wide form

table4a_long <- table4a %>%
    
    pivot_longer(cols = c('1999', '2000'),
                 names_to = "year", 
                 values_to = "cases")

wide to long form

table4a_long %>% 
    
    pivot_wider(names_from = year, 
                values_from = cases)
## # A tibble: 3 × 3
##   country     `1999` `2000`
##   <chr>        <dbl>  <dbl>
## 1 Afghanistan    745   2666
## 2 Brazil       37737  80488
## 3 China       212258 213766

Separating and Uniting

Separating a column

table3_sep <- table3 %>%
    
    separate(col = rate, into = c("cases", "population"))

Unite two columns

table3_sep %>%
    
    unite(col = "rate", c(cases, population), sep = "/")
## # A tibble: 6 × 3
##   country      year rate             
##   <chr>       <dbl> <chr>            
## 1 Afghanistan  1999 745/19987071     
## 2 Afghanistan  2000 2666/20595360    
## 3 Brazil       1999 37737/172006362  
## 4 Brazil       2000 80488/174504898  
## 5 China        1999 212258/1272915272
## 6 China        2000 213766/1280428583

Missing Values

bikes <- tibble(
  bike_model   = c("A","A", "B", "B", "C"),
  material    = c("steel", "aluminum", "steel", "aluminum", "steel"),
  price = c(100, 200, 300, 400, 500)
)
bikes %>%
    
    pivot_wider(names_from = bike_model, values_from = price)
## # A tibble: 2 × 4
##   material     A     B     C
##   <chr>    <dbl> <dbl> <dbl>
## 1 steel      100   300   500
## 2 aluminum   200   400    NA
bikes %>%
    
    complete(bike_model, material)
## # A tibble: 6 × 3
##   bike_model material price
##   <chr>      <chr>    <dbl>
## 1 A          aluminum   200
## 2 A          steel      100
## 3 B          aluminum   400
## 4 B          steel      300
## 5 C          aluminum    NA
## 6 C          steel      500
treatment <- tribble(
  ~ person,           ~ treatment, ~response,
  "Derrick Whitmore", 1,           7,
  NA,                 2,           10,
  NA,                 3,           9,
  "Katherine Burke",  1,           4
)

treatment %>%
    
    fill(person, .direction = "down")
## # A tibble: 4 × 3
##   person           treatment response
##   <chr>                <dbl>    <dbl>
## 1 Derrick Whitmore         1        7
## 2 Derrick Whitmore         2       10
## 3 Derrick Whitmore         3        9
## 4 Katherine Burke          1        4

Non-tidy data