Count number of rows where a value appears in any of two columns in R

Question

I have a dataset like this:

data <- read.csv(text = "foo,bar
a,b
a,a
b,c
c,a
c,b")

I want to compute a table that tells me in how many rows every possible value appears, so something like this:

Value	Count
a	3
b	3
c	3

I've tried grouping by the two columns using dplyr and then summarise, but that does not give you a count per value, but per column value. Any idea?

Answer 1

With dplyr, tibble and tidyr, you could do:

data %>%
 mutate(across(everything(), trimws)) %>%
 rowid_to_column() %>%
 pivot_longer(-rowid) %>%
 group_by(value) %>%
 summarise(n = n_distinct(rowid))

  value     n
  <chr> <int>
1 a         3
2 b         3
3 c         3