R help - Jul 2007 - how to create matrix in a loop

Hi all,
How does one create a matrix of values in a loop. For example, I have 46*70
matrix with columns giving the values for some blood tests performed upon
the 46 patients(rows). I want to perform a simple test of normality
(shapiro-wilk test) upon each of the biochemical tests for the 46
patients. Can somebody suggest the syntax for such a loop. For the data x, I
wrote the following loop which didnt work:-
pv<-1:70
stat<-1:70
for(i in 1:70)
{
pv[i]=shapiro.test(x[,i])$p.value
stat[i]<-shapiro.test(x[,i])$statistic
}
warning msg: items to replace is not a multiple of replacement length

Does it have anything to do with the method of importing data as
read.delimrather than
read.table?
Please suggest

	[[alternative HTML version deleted]]

You don't need to do a loop.  You can do it with an
apply statement I think. See ?apply

If the matrix is "mat" to do the test by column try:

apply(mat, 2, shapiro.test)


--- Tavpritesh Sethi <tavpritesh at gmail.com> wrote:
> Hi all,
> How does one create a matrix of values in a loop.
> For example, I have 46*70
> matrix with columns giving the values for some blood
> tests performed upon
> the 46 patients(rows). I want to perform a simple
> test of normality
> (shapiro-wilk test) upon each of the biochemical
> tests for the 46
> patients. Can somebody suggest the syntax for such a
> loop. For the data x, I
> wrote the following loop which didnt work:-
> pv<-1:70
> stat<-1:70
> for(i in 1:70)
> {
> pv[i]=shapiro.test(x[,i])$p.value
> stat[i]<-shapiro.test(x[,i])$statistic
> }
> warning msg: items to replace is not a multiple of
> replacement length
> 
> Does it have anything to do with the method of
> importing data as
> read.delimrather than
> read.table?
> Please suggest