Count number of individuals detected in one group or both-CodePudding

I have a data frame with individuals and which site they were detected.

ID      Location       
5994    Greshornish
5994    Snizort    
6017    Greshornish
6018    Greshornish
6020    Greshornish
6020    Snizort
6021    Greshornish
46507   Greshornish
46508   Snizort
46511   Greshornish
46512   Greshornish
46512   Snizort

I would like to count the number of individuals detected at one site or both. For example, in the table above I would get something like

Location      Count
Greshornish     5
Snizort         1 
Both            3

I can't figure out the best way to do this although I'm sure it's quite simple.

CodePudding user response：

library(dplyr)
df %>% 
  group_by(ID) %>% 
  summarise(Location = ifelse(n() == 2, "Both", Location)) %>% 
  count(Location, name = "Count")

#   Location    Count
# 1 Both            3
# 2 Greshornish     5
# 3 Snizort         1

CodePudding user response：

This should work:)

library(dplyr) 
df %>% group_by(Location) %>% tally() %>% rename(Count = n)