aggregate - R Aggregation Error: count distinct -

i'm relatively new r, forgive me if seems dumb question. i've started run out of ideas other examples on how make work, , hoping guide me in right direction working.

so i'm attempting count distinct on site_id clncl_trial_id.

my data in dataframe (data2), kind of looks like:

clncl_trial_id: 89794, 89794, 8613, 8613  site_id: 12456, 12456, 100341, 30807 

the idea end result count of 89794=1 , 8613=2

here's have far:

z <- aggregate(data2$site_id ~ data2$clncl_trial_id, data2, function(site_id) length(unique(data2$site_id))) 

and i've attempted alternate forms

aggregate(site_id ~ clncl_trial_id, data2, sum(!duplicated(data$site_id)))    aggregate(site_id ~ clncl_trial_id, data2, nlevels(factor(data2$site_id)))    aggregate(site_id ~ clncl_trial_id, data2, function(site_id) length(unique(data2$site_id))) 

i keep running problem instead of grouping trial_id, counting whole table. 89794=3 , 8613=3.

does have idea how correct issue? feel i'm overlooking silly. also, side note: i'm trying keep limited base package of r if @ possible. if isn't possible, no biggie.

a couple of methods:

data:

df <- data.frame(clncl_trial_id = c(89794, 89794,8613, 8613), site_id = c(12456, 12456, 100341, 30807)) 

base r - table:

table(df)                site_id clncl_trial_id 12456 30807 100341      8613      0     1      1      89794     2     0      0 

dplyr:

library(dplyr) df %>%    group_by(clncl_trial_id, site_id) %>%   summarise(count = n())    clncl_trial_id site_id count 1           8613   30807     1 2           8613  100341     1 3          89794   12456     2 

update

to count distinct, use unique base r, or distinct dplyr:

table(unique(df)) ## group/summarise results can use rowsums() rowsums(table(unique(df)))   df %>% distinct %>% group_by(clncl_trial_id) %>% summarise(count = n()) 

or, more succintly using marek's suggestion

df %>% distinct %>% count(clncl_trial_id)