Question

I have a string in some text of the form "12,34,77", including the quotation marks.

I need to get the values of each of those numbers into a list. I tried using lapply and strsplit:

control2=lapply(strsplit(data$values,","),as.numeric)

but I get the error:

non character argument

What am I doing wrong?

Answer 1

1) strapply

1a) scalar Here is a one-liner using strapply from the gsubfn package:

library(gsubfn)
x <- '"12,34,567"'

strapply(x, "\\d+", as.numeric, simplify = c)
## [1]  12  34 567

1b) vectorized A vectorized version is even simpler — just remove the simplify=c like this:

v <- c('"1,2,3"', '"8,9"') # test data
strapply(v, "\\d+", as.numeric)`

2) gsub and scan

2a) scalar and here is a one-linear using gsub and scan:

scan(text = gsub('"', '', x), what = 0, sep = ",")
## Read 3 items
## [1]  12  34 567

2b) vectorized A vectorized version would involve lapply-ing over the components:

lapply(v, function(x) scan(text = gsub('"', '', x), what = 0, sep = ","))

3) strsplit

3a) scalar and here is a strsplit solution. Note that we split on both " and , :

as.numeric(strsplit(x, '[",]')[[1]][-1])
## [1]  12  34 567

3b) vectorized A vectorized solution would, again, involve lapply-ing over the components:

lapply(v, function(x) as.numeric(strsplit(x, '[",]')[[1]][-1]))

3c) vectorized – simpler or slightly simpler:

lapply(strsplit(gsub('"', '', v), split = ","), as.numeric)