R help - Oct 2006 - Qualitative Data??(String command)

I am using the read.table function to load an Excel data set into R.
It has a few variables with very long qualitative (free response
typically in sentences) response that I would like to keep, but would
like to limit the "length" of the response that R shows. Is there some
sort of string or column width command I can include in the read.table
function to limit the length of words used in the variables that have
long responses?? I do know which variable names are the ones with the
qualitative responses. Will the Rcmdr program do this for me? I know
STATA has this function but I don't have it on my computer to use.

Davia


-- 
Davia S. Cox
"Image creates desire. You will what you imagine."
~J.G. Gallimore~

Dear Davia,
> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Davia Cox
> Sent: Friday, October 27, 2006 3:37 PM
> To: r-help at stat.math.ethz.ch
> Subject: [R] Qualitative Data??(String command)
> 
> I am using the read.table function to load an Excel data set into R.
> It has a few variables with very long qualitative (free 
> response typically in sentences) response that I would like 
> to keep, but would like to limit the "length" of the response 
> that R shows. Is there some sort of string or column width 
> command I can include in the read.table function to limit the 
> length of words used in the variables that have long 
> responses?? I do know which variable names are the ones with 
> the qualitative responses. Will the Rcmdr program do this for 
> me? 
No. When you read an Excel file (or an ascii file) into R using the Rcmdr,
character data will be converted into factors.
> I know STATA has this function but I don't have it on my 
> computer to use.
>
If I understand you correctly, it's not hard to do what you want. The
following function takes a data frame and desired character length as
arguments and truncates both character variables and the levels of factors.
Note that you have to be a little careful with factors in that you could
truncate different levels to the same string, inadvertently combining them.

truncateValues <- function(Data, len=10){
    for (i in 1:ncol(Data)){
        var <- Data[[i]]
        if (is.factor(var)) {
            levels(var) <- sapply(levels(var), 
                function(x) substr(x, 1, min(nchar(x), len)))
            Data[[i]] <- var
            }
        else if (is.character(var)) {
            Data[[i]] <- sapply(var, function(x) substr(x, 1, min(nchar(x),
len)))
            }
        }
    Data
    }

I hope this helps,
 John
> Davia
> 
> 
> --
> Davia S. Cox
> "Image creates desire. You will what you imagine."
> ~J.G. Gallimore~
> 
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