[R] unable to force the vector format

[Charles Plessy]

Dear all,

I am so ashamed to pollute the list with a trivial question, but it is a
long time I have not used R, and I need a result in the next one or two
hour...

I have a table which I have loaded with read.table, and I want to make
the mean of its columns.

> slides <- read.table("slides.txt")
> slides [1:5,]
            V1    V2     V3     V4     V5     V6     V7     V8
1 PLB00090AA02 0.147  0.018  0.046  0.064 -0.018 -0.008 -0.063
2 PLB00090BC08 0.171  0.011 -0.001  0.009  0.052  0.032 -0.065
3 PLB00090CG02 0.029 -0.014 -0.042  0.006  0.024 -0.009 -0.043
4 PLB00091AA08 0.033  0.050 -0.022 -0.002  0.038  0.015 -0.037
5 PLB00091BE02 0.183  0.039  0.052 -0.014 -0.034 -0.037  0.037

but I can not get the mean :

> mean(slides [1,2:8])
    V2     V3     V4     V5     V6     V7     V8 
 0.147  0.018  0.046  0.064 -0.018 -0.008 -0.063 

obviously, I fail to tell R that I am using a vector.

> y<- c(1,2,3,4)
> mean(y)
[1] 2.5

but as.vector does not solve my problem

> lapply(as.vector(slides[1,2:8]),sum)
$V2
[1] 0.147

$V3
[1] 0.018

$V4
[1] 0.046

$V5
[1] 0.064

$V6
[1] -0.018

$V7
[1] -0.008

$V8
[1] -0.063

In the end, I would like to use lapply to fill a new column in the table with the means.
(and then extract the closest ones to zero...)

Once again, sorry for this mail, whose answer is probably trivial, but it would
be an enormous help if somebody could sent it to me!

-- 
Charles