[R] Argh! Trouble using string data read from a file

[Ted Byers]

Here is what I tried:

optdata =
read.csv("K:\\MerchantData\\RiskModel\\AutomatedRiskModel\\soptions.dat",
header = FALSE, na.strings="")
optdata
attach(optdata)
for (i in 1:length(V4) ) { x = read.csv(V4[[i]], header = FALSE,
na.strings="");x }

And here  is the outcome (just a few of the 60 records successfully read):
> optdata =
> read.csv("K:\\MerchantData\\RiskModel\\AutomatedRiskModel\\soptions.dat",
> header = FALSE, na.strings="")
> optdata
    V1   V2 V3                        V4
1  251 2008 18 Plus_Shipping.2008.18.dat
2  251 2008 19 Plus_Shipping.2008.19.dat
3  251 2008 20 Plus_Shipping.2008.20.dat
4  251 2008 22 Plus_Shipping.2008.22.dat
5  251 2008 23 Plus_Shipping.2008.23.dat
6  251 2008 24 Plus_Shipping.2008.24.dat

I can see the data has been correctly read.  But for some reason that isn't
clear, read.csv doesn't like the data in the last column.

> attach(optdata)
> for (i in 1:length(V4) ) { x = read.csv(V4[[i]], header = FALSE,
> na.strings="");x }
Error in read.table(file = file, header = header, sep = sep, quote = quote, 
: 
  'file' must be a character string or connection
> V4[[1]]
[1] Plus_Shipping.2008.18.dat
60 Levels: Easyway.2008.17.dat Easyway.2008.18.dat Easyway.2008.19.dat
Easyway.2008.20.dat ... Secured_Pay.2008.31.dat

>

The last column is comprised of valid Windows filenames (and no whitespace,
so as not to confuse things).

I see in the docuentation "`[[...]]' is the operator used to select a single
element, whereas `[...]' is a general subscripting operator.", so I assume
V4[[i]] is the correct way to get the ith value from V4.  So why does
read.csv complain that "'file' must be a character string or connection"? 
It seems obvious that the value in V4[[i]i] is a string.  V4[[1]] does give
me the right value, although that is followed by output I didn't ask for.

In the loop above, I was going to replace the output obtained by 'x' with
output from fitdistr(x,"exponential"), but I can't proceed with that until I
can get the data in these files read.

What have I missed?

Thanks

Ted
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