Conditional filtering using grepl and relative row position in group

Question

I have a dataset similar to the following:

Journal_ref <- c("1111","2222","2222","2222","3333","3333","4444","4444")
Journal_type <- c("Adj","Rev","Adj","Rev","Rev","Rev","Adj","Adj")
Journal_value <- c(90,10000,12000,80,9000,500,65,2500)
Dataset <- data.frame(Journal_ref,Journal_type,Journal_value)

For each Journal_ref group I am seeking to filter/select rows based on the following conditions:

• Where "Adj" is included within Journal_type, filter/select to return the last "Adj" row in the Journal_ref group, and
• Where "Adj" is not included within Journal_type, filter/select to return the last "Rev" in the Journal_ref group

Based on the example above, the final output required would be:

Journal_ref Journal_type Journal_value
1111        Adj                    90
2222        Adj                 12000
3333        Rev                   500
4444        Adj                  2500

I have attempted using various combinations of group_by, filter, if, ifelse, grepl, select and slice with no success.

Any help would be appreciated, particularly using dplyr.

Answer 1

Try this:

library(dplyr)

Dataset %>%
  group_by(Journal_ref, Journal_type) %>%
  summarise(Journal_value = last(Journal_value)) %>%
  ungroup() %>% group_by(Journal_ref) %>%
  filter(!(n() > 1 & Journal_type == "Rev"))

Output:

  Journal_ref Journal_type Journal_value
  <fct>       <fct>                <dbl>
1 1111        Adj                     90
2 2222        Adj                  12000
3 3333        Rev                    500
4 4444        Adj                   2500