Thanks a bunch. Can't believe I missed that.
-----Original Message-----
From: Rui Barradas [mailto:ruipbarra...@sapo.pt]
Sent: Tuesday, June 18, 2013 9:57 AM
To: Davis, Brian
Cc: r-help@r-project.org
Subject: Re: [R] Help understanding environments
Hello,
The first argument to exists() must be the name of an object given as a
character string, as stated in the help page. See ?exists. You have also forgot
to initialize combined to NULL, this time.
Your function revised would then become
c_objects <- function(FILES) {
combined <- NULL
for (FILE in FILES) {
load(FILE)
if (exists("combined")) {
combined <- c(combined, res)
} else {
combined <- res
}
}
return(combined)
}
And all works as expected.
Hope this helps,
Rui Barradas
Em 18-06-2013 14:57, Davis, Brian escreveu:
> In my haste to make a smaller example than my actual code I used
> 'is.null' instead of 'exists' as is in my code. Here's a small
> reproducible example
>
>
> res <- list(abc=letters, ABC=LETTERS)
> save(res, file="results.RData")
> res <- list(zyx=rev(letters), ZYX=rev(LETTERS)) save(res,
> file="results2.RData")
>
> rm(res)
> FILES <- c("results.RData", "results2.RData")
>
>
> c_objects <- function(FILES) {
> for (FILE in FILES) {
> load(FILE)
> if (exists(combined)) {
> combined <- c(combined, res)
> } else {
> combined <- res
> }
> }
> return(combined)
> }
>
> combined_results <- c_objects(FILES)
>
>
> -----Original Message-----
> From: Duncan Murdoch [mailto:murdoch.dun...@gmail.com]
> Sent: Monday, June 17, 2013 5:40 PM
> To: Davis, Brian
> Cc: r-help@r-project.org
> Subject: Re: [R] Help understanding environments
>
> On 13-06-17 5:02 PM, Davis, Brian wrote:
>> I have a collection of .RData files that have result objects that I would
>> like to combine. Specifically, skatCohort objects from the skatMeta
>> package, but I've run into a similar issue with simple data.frames also.
>>
>> If I run something like
>>
>> FILES <- list.files(path="/path/to/my/results", pattern=".RData$",
>> full.names=TRUE) combined <- NULL
>> for (FILE in FILES) {
>> load(FILE)
>> if (!is.null(combined)) {
>> combined <- c(combined, res)
>> } else {
>> combined <- res
>> }
>> }
>>
>> I get all my objects combined. However, if I wrap this into a
>> function I get the following error
>>
>> c_objects <- function(FILES) {
>> combined <- NULL
>> for (FILE in FILES) {
>> load(FILE)
>> if (!is.null(combined)) {
>> combined <- c(combined, res)
>> } else {
>> combined <- res
>> }
>> }
>> return(combined)
>> }
>>
>> combined_results <- c_objects(FILES)
>> Error in eval(expr, envir, enclos) : object 'combined' not found
>>
>> How should I write this function such that it can find "combined". I've
>> tried reading the help on envirnaments, and the exisits function but I
>> haven't been able to figure this out. Are there any other resources to read
>> up on this?
>
> You are doing something that you aren't showing us: I don't see any calls to
> eval(), but it's eval() that generated the error.
>
> Calling traceback() after the error might be informative.
>
> Duncan Murdoch
>
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