Find all unique values in column separated by comma

user_10880030 0
Viewed 1873

I have multiple observations of one species with different observers / groups of observers and want to create a list of all unique observers. My data look like this: 

data <- read.table(text="species observer
1 A,B
1 A,B
1 B,E
1 B,E
1 D,E,A,C,C
1 F"               , header = TRUE, stringsAsFactors = FALSE)

My output should return a list of all unique observers - so: 

A,B,C,E,F

I tried to substring the data in column C using the following command but that only returns the unique combinations of observers. 

all_observers <- unique(strsplit(as.character(data$observer), ","))

all_observers
[[1]]
[1] "A" "B"

[[2]]
[1] "B" "E"

[[3]]
[1] "D" "E" "A" "C" "C"

[[4]]
[1] "F"
strsplit r
3 Answers

You're almost there, you just need to unlist before you do the unique:

all_observers <- unique(unlist(strsplit(as.character(data$observer), ",")))
user_9030610

We can use separate_rows on the 'observer', get the distinct rows, grouped by 'species', and paste the 'observer'

library(tidyverse)
data %>% 
   separate_rows(observer) %>% 
   distinct %>% 
   group_by(species) %>% 
   summarise(observer = toString(observer))
user_37322710

You could also use scan()

unique(scan(text=data$observer, what="", sep=","))
# Read 14 items
# [1] "A" "B" "E" "D" "C" "F"
user_30639100
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