On 2011-06-29 15:02, David Winsemius wrote:
On Jun 29, 2011, at 4:56 PM, katarv wrote:
Hi Sarah,
I use readMat function, from R.matlab function.
str(X) tells that
X : num [1:64, 1:64, 1:21, 1:300] as I said, the first 3 columns
are x,y,z
coordinates. And I need all values in the last column correcponding
to a
given (x,y,z) coordinate.
You should be able to access those values with:
X[1,1,1, ]
or equivalently:
X[1,1,1,1:300]
if you list the values of X,
then they are non zero, but for some reason R
tells that dim(X): NULL
Now that seems a bit odd. What happens if you try:
I think that Katia is not telling us the whole story. According to
its documentation, readMAT returns a *list* named X, presumably in
this case containing just the X element. So my guess is that str(X)
actually said:
List of 1
$ X : num [1:64, 1:64, 1:21, 1:300] ....
Naturally, dim(X) is NULL.
Katia probably just needs to do do two things:
1. extract array X from list X (e.g. with X <- X$X).
2. learn to read the documentation of functions she's trying to use.
Peter Ehlers
Y<- X
dim(Y)<- c(64,64,21,300)
Y[ 1, 1, 1, ]
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David Winsemius, MD
West Hartford, CT
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______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
