Question

When I have a vector of vectors in R, how do I select a vector that contains one element from each outer vector?

For example, given this data:

> data<-c("1,2","3,4","5,6")
> data<-strsplit(data,",")
> data
[[1]]
[1] "1" "2"

[[2]]
[1] "3" "4"

[[3]]
[1] "5" "6"

How do I get a vector containing (1,3,5) and nothing else?

Thanks!

Answer 1

Since your example uses strsplit I assume this is how you obtain your dataset in the first place? If so, using regular expressions also work and might be slightly faster. e.g.

data <- c("1,2","3,4","5,6")

# Remove everything after ,:
gsub(",.*","",data)

# Select first number:
regmatches(data,regexpr("\\d+",data))