How to expand rows and fill in the numbers between given start and end

Question

I have this data frame:

df <- tibble(x = c(1, 10))

      x
  <dbl>
1     1
2    10

I want this:

      x
   <int>
 1     1
 2     2
 3     3
 4     4
 5     5
 6     6
 7     7
 8     8
 9     9
10    10

Unfortunately I can't remember how I have to approach. I tried expand.grid, uncount, runner::fill_run.

Update: The real world data ist like this with groups and given start and end number. Here are only two groups:

  df <- tibble(group = c("A", "A", "B", "B"), 
               x = c(10,30, 1, 10)) 

  group     x
  <chr> <dbl>
1 A        10
2 A        30
3 B         1
4 B        10

Answer 1

We may need full_seq with either summarise or reframe or tidyr::complete

library(dplyr)
df %>% 
   group_by(group) %>%
   reframe(x = full_seq(x, period = 1))
   # or with 
   #tidyr::complete(x = full_seq(x, period = 1))

-output

# A tibble: 31 × 2
   group     x
   <chr> <dbl>
 1 A        10
 2 A        11
 3 A        12
 4 A        13
 5 A        14
 6 A        15
 7 A        16
 8 A        17
 9 A        18
10 A        19
# … with 21 more rows