Process a dataframe by its column names

Question

For example, I have a dataframe like this:

df = data.frame(
  name = c('A', 'B', 'C'),
  a = c(1, 2, 3),
  b = c(4,5,6),
  c = c(7,8,9))

Eventually, I form a dataframe with this format:

Hence, what should I do to process this dataframe in this format?

Thank you.

Answer 1

tidyr::pivot_longer(df, -name, values_to = "number", names_to = "letter")
# A tibble: 9 × 3
  name  letter number
  <chr> <chr>   <dbl>
1 A     a           1
2 A     b           4
3 A     c           7
4 B     a           2
5 B     b           5
6 B     c           8
7 C     a           3
8 C     b           6
9 C     c           9