Read csv file in R with double quotes

Question

Suppose I have a csv file looks like this:

Type,ID,NAME,CONTENT,RESPONSE,GRADE,SOURCE
A,3,\"\",\"I have comma, ha!\",I have open double quotes\",A,\"\"
         


        

Answer 1

This is not valid CSV, so you'll have to do your own parsing. But, assuming the convention is as follows, you can just toggle with scan to take advantage of most of its abilities:

1. If the field starts with a quote, it is quoted.
2. If the field does not start with a quote, it is raw

next_field<-function(stream) {
  p<-seek(stream)
  d<-readChar(stream,1)
  seek(stream,p)
  if(d=="\"")    
    field<-scan(stream,"",1,sep=",",quote="\"",blank=FALSE)   
  else
    field<-scan(stream,"",1,sep=",",quote="",blank=FALSE)
  return(field)
}

Assuming the above convention, this sufficient to parse as follows

s<-file("example.csv",open="rt")
header<-readLines(s,1)
header<-scan(what="",text=header,sep=",")
line<-replicate(length(header),next_field(s))

setNames(as.data.frame(lapply(line,type.convert)),header)

  Type ID NAME           CONTENT                   RESPONSE GRADE SOURCE
1    A  3   NA I have comma, ha! I have open double quotes"     A     NA

However, in practice you might want to first write back the fields, quoting each, to another file, so you can just read.csv on the corrected format.