R help - Oct 2014 - write.table produces a file that read.table can't read

Hi,

I'm using R version 3.1.1 on Debian via the CRAN repositories.

Consider the following MWE that writes a data.frame out to a file and
reads it back in (note that one of the strings contains a double
quote):

  > write.table(data.frame(a=1:3, b=c("a", "b\"b",
"c")), '/tmp/a', row.names=FALSE, na="?",
sep=",")
  > read.table('/tmp/a', header=TRUE, row.names=NULL,
sep=',', na.strings='?', allowEscapes=T)
  [1] a b
  <0 rows> (or 0-length row.names)

/tmp/a contains the following:

  $ cat /tmp/a 
  "a","b"
  1,"a"
  2,"b\"b"
  3,"c"

Removing the double quote, it works:

  > write.table(data.frame(a=1:3, b=c("a", "bb",
"c")), '/tmp/a', row.names=FALSE, na="?",
sep=",")
  > read.table('/tmp/a', header=TRUE, row.names=NULL,
sep=',', na.strings='?', allowEscapes=T)
    a  b
  1 1  a
  2 2 bb
  3 3  c

Why does allowEscapes not work for double quotes?  Or, why does
write.table produce a file that read.table can't read!

Thanks for any advice!

Neal

How about:

tmp <- data.frame(a=1:3, b=c("a", "b\"b",
"c"))

write.table(tmp, './tmp.write', row.names=FALSE, sep="\t?,
quote=FALSE)

tmp.in <- read.table('./tmp.write', sep='\t', head=TRUE,
quote="")


> all.equal(tmp, tmp.in)
[1] TRUE



-Don

-- 
Don MacQueen

Lawrence Livermore National Laboratory
7000 East Ave., L-627
Livermore, CA 94550
925-423-1062





On 10/8/14, 7:22 AM, "Neal H. Walfield" <neal at walfield.org>
wrote:
>Hi,
>
>I'm using R version 3.1.1 on Debian via the CRAN repositories.
>
>Consider the following MWE that writes a data.frame out to a file and
>reads it back in (note that one of the strings contains a double
>quote):
>
>  > write.table(data.frame(a=1:3, b=c("a",
"b\"b", "c")), '/tmp/a',
>row.names=FALSE, na="?", sep=",")
>  > read.table('/tmp/a', header=TRUE, row.names=NULL,
sep=',',
>na.strings='?', allowEscapes=T)
>  [1] a b
>  <0 rows> (or 0-length row.names)
>
>/tmp/a contains the following:
>
>  $ cat /tmp/a 
>  "a","b"
>  1,"a"
>  2,"b\"b"
>  3,"c"
>
>Removing the double quote, it works:
>
>  > write.table(data.frame(a=1:3, b=c("a", "bb",
"c")), '/tmp/a',
>row.names=FALSE, na="?", sep=",")
>  > read.table('/tmp/a', header=TRUE, row.names=NULL,
sep=',',
>na.strings='?', allowEscapes=T)
>    a  b
>  1 1  a
>  2 2 bb
>  3 3  c
>
>Why does allowEscapes not work for double quotes?  Or, why does
>write.table produce a file that read.table can't read!
>
>Thanks for any advice!
>
>Neal
>
>______________________________________________
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