[R] Errors, driving me nuts

[Ista Zahn]

Hi Matt,

On Mon, Aug 1, 2011 at 4:47 PM, Matt Curcio <matt.curcio.ri at gmail.com> wrote:
> Greetings all,
> I am getting this error that is driving me nuts... (not a long trip, haha)
>
> I have a set of files and in these files I want to calculate ttests on
> rows 'compareA' and 'compareB' (these will change over time there I
> want a variable here). Also these files are in many different
> directories so I want a way filter out the junk...  Anyway I don't
> believe that this is related to my errors but I mention it none the
> less.
>
>> files_to_test <- list.files (pattern = "kegg.combine")
>> for (i in 1:length (files_to_test)) {
> +    raw_data <- read.table (files_to_test[i], header=TRUE, sep=" ")
> +    tmpA <- raw_data[,compareA]
> +    tmpB <- raw_data[,compareB]
> +    tt <- t.test (tmpA, tmpB, var.equal=TRUE)
> +    tt_pvalue[i] <- tt$p.value
> + }
> Error in tt_pvalue[i] <- tt$p.value : object 'tt_pvalue' not found
> # I tried setting up a vector...
> # as.vector(tt_pvalue, mode="any") ### but NO GO
>> file.name = paste("ttest.results.", compareA, compareB, "")
>> setwd(save_to)
>> write.table(tt_pvalue, file=file.name, sep="\t" )
> Error in inherits(x, "data.frame") : object 'tt_pvalue' not found
> # No idea??

you need to create tt_pvalue before you can assign values to it (i.e.,
before you start your for-loop). Consider this simpler example:

tst[1] <- 1
Error in tst[1] <- 1 : object 'tst' not found
tst <- vector()
tst[1] <- 1

Best,
Ista



>
> What is going wrong??
> M
>
>
> Matt Curcio
> M: 401-316-5358
> E: matt.curcio.ri at gmail.com
>
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>



-- 
Ista Zahn
Graduate student
University of Rochester
Department of Clinical and Social Psychology
http://yourpsyche.org