[R] write.table() adds unnecessary spaces to right align integer column

[Henrik Bengtsson]

When using write.table() to write data frames the integer columns are padded
with unnecessary spaces (0x20) so that these columns are right align if you
look at them in a text editor. However, I think it is quite a vast of file
size. For instance, I am reading a tab-delimited 4200kb microarray data file
and writing it back verbatim using write.table() and it becomes 5100kb, a
20% increase. Is this problem known and is there anyway to get around it?

Example (R --vanilla):

x <- c(0,1,10,100,1e3,1e5,1e6)
df <- data.frame(a=x, b=as.integer(x), c=as.character(x))
write.table(df, "out.dat")


Output:

"a" "b" "c"
"1" 0e+00       0 "0"
"2" 1e+00       1 "1"
"3" 1e+01      10 "10"
"4" 1e+02     100 "100"
"5" 1e+03    1000 "1000"
"6" 1e+05  100000 "1e+05"
"7" 1e+06 1000000 "1e+06"


str(R.Version()):
 $ platform: chr "i386-pc-mingw32"
 $ arch    : chr "i386"
 $ os      : chr "mingw32"
 $ system  : chr "i386, mingw32"
 $ status  : chr ""
 $ major   : chr "1"
 $ minor   : chr "5.1"
 $ year    : chr "2002"
 $ month   : chr "06"
 $ day     : chr "17"
 $ language: chr "R"

Thanks

Henrik Bengtsson

Dept. of Mathematical Statistics @ Centre for Mathematical Sciences
Lund Institute of Technology/Lund University, Sweden (+2h UTC)
+46 46 2229611 (off), +46 708 909208 (cell), +46 46 2224623 (fax)
h b @ m a t h s . l t h . s e, http://www.maths.lth.se/bioinformatics/

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