I have a dataset ('DF1') that I want to know how many times each instance of 'Species' appears per 'Date' per 'Site'. My actual data set has five dates per site and there are ten sites, but I've condensed it quite a bit here.

I can summarize the counts for one Species at a time using this code:

DF1 %>% group_by(Site,Date) %>% 
  filter(Species=="AMCR") %>%
  summarise(count_Species = n())

This will return the count for 'AMCR' for each site on each date, but it would be too tedious to do this for each Species and then combine all those results into one dataframe.

Is there a way to loop this for each unique instance of species and then paste them together into one dataframe?

Thank you!

CodePudding user response：

We could use count from dplyr package!

library(dplyr)
df %>% 
  as_tibble() %>%
  count(Species, Date, Site)

   Species Date      Site      n
   <chr>   <chr>     <chr> <int>
 1 AMCR    5/27/2021 SVC      11
 2 AMRO    6/1/2021  TMC       4
 3 DEJU    6/1/2021  TMC      15
 4 HAFL    6/1/2021  TMC       4
 5 LEGO    5/27/2021 SVC       1
 6 LISP    5/27/2021 SVC       8
 7 LISP    6/1/2021  TMC      16
 8 MOCH    6/1/2021  TMC       1
 9 PISI    6/1/2021  TMC       3
10 RCKI    5/27/2021 SVC       2
11 RCKI    6/1/2021  TMC      14
12 RECR    6/1/2021  TMC       5
13 SAVS    5/27/2021 SVC      18
14 STJA    6/1/2021  TMC       2
15 YRWA    5/27/2021 SVC      12
16 YRWA    6/1/2021  TMC      17