[R] read.csv quotes within fields

[David Winsemius]

On Jan 25, 2013, at 10:42 AM, Tim Howard wrote:

> All,
> 
> I have some csv files I am trying to import. I am finding that quotes inside strings are escaped in a way R doesn't expect for csv files. The problem only seems to rear its ugly head when there are an uneven number of internal quotes. I'll try to recreate the problem:
> 
> # set up a matrix, using escape-quote as the internal double quote mark.
> 
> x <- data.frame(matrix(data=c("1", "string one", "another string", "2", "quotes escaped 10' 20\" 5' 30\" \"test string", "final string", "3","third row","last \" col"),ncol = 3, byrow=TRUE))
> 
>> write.csv(x, "test.csv")
> 
> # NOTE that write.csv correctly created the three internal quotes ' " ' by using double quotes ' "" '. 
> # here's what got written
> 
> "","X1","X2","X3"
> "1","1","string one","another string"
> "2","2","quotes escaped 10' 20"" 5' 30"" ""test string","final string"
> "3","3","third row","last "" col"
> 
> # Importing test.csv works fine.
> 
>> read.csv("test.csv")
>  X X1                                         X2             X3
> 1 1  1                                 string one another string
> 2 2  2 quotes escaped 10' 20" 5' 30" "test string   final string
> 3 3  3                                  third row     last " col
> # this looks good. 
> # now, please go and open "test.csv" with a text editor and replace all the double quotes '""' with the 
> # quote escaped ' \" ' as is found in my data set. Like this:
> 
> "","X1","X2","X3"
> "1","1","string one","another string"
> "2","2","quotes escaped 10' 20\" 5' 30\" \"test string","final string"
> "3","3","third row","last \" col"

Use quote="":

> read.csv(text='"","X1","X2","X3"
+ "1","1","string one","another string"
+ "2","2","quotes escaped 10\' 20"" 5\' 30"" ""test string","final string"
+ "3","3","third row","last "" col"', sep=",", quote="")

Not ...., quote="\""


  X.. X.X1.                                           X.X2.            X.X3.
1 "1"   "1"                                    "string one" "another string"
2 "2"   "2" "quotes escaped 10' 20"" 5' 30"" ""test string"   "final string"
3 "3"   "3"                                     "third row"    "last "" col"

You will then be depending entirely on commas to separate. 

(Needed to use escaped single quotes to illustrate from a command line.)

> 
> # this breaks read.csv:
> 
>> read.csv("test.csv")
>  X X1                                                                                    X2             X3
> 1 1  1                                                                            string one another string
> 2 2  2 quotes escaped 10' 20\\ 5' 30\\ \\test ( file://\test ) string,final string\n3,3,third row,last \\ col      
> 
> # we now have only two rows, with all the data captured in col2 row2
> 
> Any suggestions on how to fix this behavior? I've tried fiddling with quote="\"" to no avail, obviously. Interestingly, an even number of escaped quotes within a field is loaded correctly, which certainly threw me for a while!
> 
> Thank you in advance, 
> Tim
> 
> 

David Winsemius
Alameda, CA, USA