[R] Odp: strange error msg from lapply and lm()

[Petr PIKAL]

Hi

r-help-bounces at r-project.org napsal dne 03.05.2010 16:24:11:

> 
> I am conducting a very simple t test for two genes using lapply (i try 
to
> avoid loop since i will have thousands of genes later on). however, I 
got
> strange error msg like the followings. It looks that R is complaining my
> factor has only one level, which is not the case (I check many times).

In each split?

sum(rowSums(sapply(split(all$treatment,all$CHIPEXP_NAME), function(x) 
table(x))>0)<2)

shall tell you if there are some parts of your split which has only 1 or 
less non empty levels.

What is the result in your case? Shall be zero.

Regards
Petr


> 
> > result<- lapply(split(all,all$CHIPEXP_NAME),function(x)
> > lm(logvalue~treatment,x))
> Error in `contrasts<-`(`*tmp*`, value = "contr.treatment") : 
>   contrasts can be applied only to factors with 2 or more levels
> 
> 
> can anyone help me to dissect this problem?
> 
> thanks in advance.
> 
> 
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