[R] read.table and trouble

[Andy Bunn]

Hi all,

I'm porting a library I wrote in S-plus over to R. All but one of the
functions work fine. The only one that doesn't is really giving me a
headache. I'm admitting defeat. Can anybody help?

Object example3 has been read in using read.table. The statement works fine
in S-Plus.
When I run the same statement in R the column Prefix, which is read in using
the
as.character coercion, is wacky. It reads in as numeric.

> example3
   nRows nWaves nYears Noise  Amp Freq AmpTwo FreqTwo  Prefix
1      1      1   1000  0.02 0.01    2     NA      NA  "test"
2      2      1   1000  0.02 0.02    2     NA      NA "test2"
3      3      1   1000  0.02 0.03    2     NA      NA      NA
4      4      1   1000  0.02 0.04    2     NA      NA      NA
5      5      1   1000  0.02 0.05    2     NA      NA      NA
6      6      1   1000  0.02 0.06    2     NA      NA      NA
7      7      1   1000  0.02 0.07    2     NA      NA      NA
8      8      1   1000  0.02 0.08    2     NA      NA      NA
9      9      1   1000  0.02 0.09    2     NA      NA "test3"
10    10      1   1000  0.02 0.10    2     NA      NA      NA
11    11      2   1000  0.02 0.01    2   0.01       5      NA
12    12      2   1000  0.02 0.02    2   0.02       5      NA
13    13      2   1000  0.02 0.03    2   0.03       5      NA
14    14      2   1000  0.02 0.04    2   0.04       5      NA
15    15      2   1000  0.02 0.05    2   0.05       5      NA
16    16      2   1000  0.02 0.06    2   0.06       5      NA
17    17      2   1000  0.02 0.07    2   0.07       5      NA
18    18      2   1000  0.02 0.08    2   0.08       5      NA
19    19      2   1000  0.02 0.09    2   0.09       5      NA
20    20      2   1000  0.02 0.10    2   0.10       5      NA
> attach(example3)
> Prefix[1]
[1] 3
> Prefix[2]
[1] NA
> is.numeric(Prefix[1])
[1] TRUE
> is.character(Prefix[1])
[1] FALSE


Here's the read.table command:

DriverTable <- read.table(file = DriverFile, header = T, sep = ",",
row.names = NULL, na.strings = "NA")

I then pass a bunch of arguments to another function like so:

for(i in 1:length(nRows))
	{
		RingSim(nWaves[i], nYears[i], Noise[i], Amp[i], Freq[i], AmpTwo[i],
FreqTwo[i], as.character(Prefix[i]))
	}

This works in S. All the variables (nWaves, nYears, etc.) are numeric except
Prefix. How can I read Prefix in correctly - that is as a string.

Here's the file that is read in:

nRows, nWaves, nYears, Noise, Amp, Freq, AmpTwo, FreqTwo, Prefix
1,1,1000,0.02,0.01,2,NA,NA,test1
2,1,1000,0.02,0.02,2,NA,NA,test2
3,1,1000,0.02,0.03,2,NA,NA,NA
4,1,1000,0.02,0.04,2,NA,NA,test3
5,1,1000,0.02,0.05,2,NA,NA,NA
6,1,1000,0.02,0.06,2,NA,NA,NA
7,1,1000,0.02,0.07,2,NA,NA,NA
8,1,1000,0.02,0.08,2,NA,NA,NA
9,1,1000,0.02,0.09,2,NA,NA,test4
10,1,1000,0.02,0.1,2,NA,NA,NA
11,2,1000,0.02,0.01,2,0.01,5,NA
12,2,1000,0.02,0.02,2,0.02,5,NA
13,2,1000,0.02,0.03,2,0.03,5,NA
14,2,1000,0.02,0.04,2,0.04,5,NA
15,2,1000,0.02,0.05,2,0.05,5,NA
16,2,1000,0.02,0.06,2,0.06,5,NA
17,2,1000,0.02,0.07,2,0.07,5,NA
18,2,1000,0.02,0.08,2,0.08,5,NA
19,2,1000,0.02,0.09,2,0.09,5,NA
20,2,1000,0.02,0.1,2,0.1,5,NA

Why on earth is everything read in correctly except the Prefix column? Why
does Prefix[1] return 3 and the rest of the column is NA?

Thanks in advance,
Andy

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