How to split TOP N and rest by category in R?

Question

I have the following dataframe:

Sale <- c("30","45","23","33","24","11","56","19","45","56","33","32","89","33","12","18","10","17")
category <- c("a","b","c","c","d","e","f","g","h","i","j","k","l","z","x","c","v","b")
growth <- c(33,16,49,57,45,67.75,90.85,10,33,76,3,77,88.98,65,98,76,45,89)
df <- data.frame(category,Sale,growth)

I want to rank/order categories by sales. Next, I need to select the TOP 9 category and put all the rest in the new category called 'others'. Finally need to add a rank column to this newly calculated df, where each row category has its rank by order and category 'other' is always stick to 10th! Like this:

  Category     Sale    Rank   growth
    l          89       1      ...
    f          56       2
    I          56       3
    h          45       4
    b          45       5
    c          36       6
    j          33       7
    k          32       8
    z          32       9
    other     164      10

Answer 1

df  %>%
  type.convert(as.is = TRUE) %>%
  mutate(rank = row_number(desc(Sale)),
         category = ifelse(rank>9, 'other', category),
         rank = ifelse(rank>9, 10, rank)) %>%
  group_by(category, rank) %>%
  summarise(Sale= sum(Sale), growth = sum(growth), .groups = 'drop') %>%
  arrange(rank)

# A tibble: 10 x 4
   category  rank  Sale growth
   <chr>    <dbl> <int>  <dbl>
 1 l            1    89   89.0
 2 f            2    56   90.8
 3 i            3    56   76  
 4 b            4    45   16  
 5 h            5    45   33  
 6 c            6    33   57  
 7 j            7    33    3  
 8 z            8    33   65  
 9 k            9    32   77  
10 other       10   164  513.