R help - Sep 2009 - Error in make.names when trying to read.table in if statement

Hi,

I'm trying to read data from a collection of CSV files for processing  
and graphing. All of my files begin with "modrate" and end with  
".csv". I think I have the regex working but I am stumped at trying to
get read.table to work within an if statement.

This works:

 > filepattern="modrate*"
 > files <- list.files(pattern=filepattern)
 > data <- read.table(files[1], header=TRUE, sep=",")

But I cannot get this to work:

 > for (i in seq(along=files)) {
+ data <- read.table(files[i], header=TRUE, sep=",")
+ }
Error in make.names(col.names, unique = TRUE) :
   invalid multibyte string at
'<ff><d8><ff><e0>'

I'm sure I'm making a newbie mistake here. I'm using R version 2.9.2
(2009-08-24) on Mac OS X, and didn't find anything about this in the  
help archives (though, as I'm new to this, I may not have searched in  
the best way). Any advice? Thanks.

Kind regards,
Cynthia

Does this work for you?

data_list <- list()
filepattern="modrate*"
all_files <- list.files(pattern=filepattern)
data_list <- lapply(all_files, read.table,header=TRUE,sep=",")

On Sep 21, 2009, at 12:19 PM, Cynthia Sadler wrote:
> Hi,
>
> I'm trying to read data from a collection of CSV files for  
> processing and graphing. All of my files begin with "modrate" and
> end with ".csv". I think I have the regex working but I am
stumped
> at trying to get read.table to work within an if statement.
>
> This works:
>
> > filepattern="modrate*"
> > files <- list.files(pattern=filepattern)
> > data <- read.table(files[1], header=TRUE, sep=",")
>
> But I cannot get this to work:
>
> > for (i in seq(along=files)) {
> + data <- read.table(files[i], header=TRUE, sep=",")
> + }
> Error in make.names(col.names, unique = TRUE) :
>  invalid multibyte string at
'<ff><d8><ff><e0>'
The error message suggests that you might have strange characters in  
your header lines which make.names()  is choking on. What is the  
result of substituting readLines with parameter of n=1 for the  
read.table() call on those files? Or perhaps you should be using "[["
rather than "[" to access the files list?

>
> I'm sure I'm making a newbie mistake here.
Despite several years, I still consider myself a newbie.
> I'm using R version 2.9.2 (2009-08-24) on Mac OS X, and didn't find
> anything about this in the help archives (though, as I'm new to  
> this, I may not have searched in the best way). Any advice? Thanks.


David Winsemius, MD
Heritage Laboratories
West Hartford, CT