R create column in new data frame if cells values match in two columns

I have a data frame ‘DF1’ with two columns that might have repeat data like such:

I want to create a new data frame ‘DF2’ that populates a new column called ‘Count’ that counts those repeats with the prefix ‘Count’. The new data frame should also include the Date and Name information from the original column so that the new data frame looks like this:

Thank you for your help!

>Solution :

To get the prefix "Count" you can use the paste() function, e.g.

library(dplyr)

df <- read.table(text = "Date   Name
2022-03-13  Bob
2022-03-13  Bob
2022-03-13  Tim
2022-03-14  Bob
2022-03-13  Tim
2022-03-14  Jim", header = TRUE)

df %>%
  group_by(Name, Date) %>%
  summarise(Count = paste("Count", n(), sep = " ")) %>%
  arrange(desc(Count))
#> `summarise()` has grouped output by 'Name'. You can override using the
#> `.groups` argument.
#> # A tibble: 4 × 3
#> # Groups:   Name [3]
#>   Name  Date       Count  
#>   <chr> <chr>      <chr>  
#> 1 Bob   2022-03-13 Count 2
#> 2 Tim   2022-03-13 Count 2
#> 3 Bob   2022-03-14 Count 1
#> 4 Jim   2022-03-14 Count 1

^{Created on 2022-08-15 by the reprex package (v2.0.1)}