Error in DESeq code

[drdna]

I've been having a lot of problems trying to tell DESeq which samples to analyze in a CountTable. My metadata table looks like this:

condition libType
PK01 col single-end
PK02 col single-end
PK07 ctrlc single-end
PK08 ctrln single-end
PK10 nho single-end
PK13 col single-end
PK15 nho single-end
PK16 nho single-end

and I'm trying to tell DESeq to compare the three "col" datasets with the "ctrlc" set. The error comes when I try to define the newCountDataSet at the start of the analysis:

> condition = factor( c( "col", "col", "ctrlc" "col"))
> library ("DESeq")
> cds = newCountDataSet( countTable, condition)
Error: length(conditions) == ncol(countData) is not TRUE

problem is there is no "conditions" variable as I can tell, only "condition"
I checked the lengths of these variables:
> length(conditions)
[1] 1
> length(condition)
[1] 4 -> what I expected

I suspect that "conditions" is an error in the code.

Also, I was unable to find the value for ncol( countTable )

> ncol(countData)
Error in ncol(countData) :
error in evaluating the argument 'x' in selecting a method for function 'ncol': Error: object 'countData' not found

Anyone have any idea what is causing this error? Better still how does one tell the program to analyze a subset of data in a larger table?

[dpryan]

You're getting an error because you're trying to assign a condition vector with only 4 elements to count data with 8 (that's what the first error message is trying to say). I'm not surprised that R is getting confused, since it has no way to know exactly what you actually want it to do! Try to subset your data (countTable) first, that'll probably solve your problem.

Alternatively, assign the full list of conditions and just use the appropriate contrasts (given the condition names, I expect just looking at the subset makes more sense).

[Wolfgang Huber]

Dear Drdna,

have a look at the "An Introduction to R" on http://cran.r-project.org/manuals.html which is a very useful introduction to the R language.

Best wishes
Wolfgang