On 30/05/2015 11:29, WRAY NICHOLAS wrote:
Hello folks
Supposing I have a multidimensional array in an R prog, say a 4D array.
I want the coordinate quantities to be read off from a vector. The values
in the vector (vec) are generated by a function.
It is not clear what you want to do.
This is easy if the number of dimensions is fixed for both the array and
the number of elements in the vector (say 4):
X<-array[vec[1],vec[2],vec[3],vec[4]]
Is 'array' an array and not the function of that name?
I am guess you are missing do.call, the way to generate calls with
variable-length argument lists. My guess of your intention could be written
arr <- array(1:256, rep(4,4))
vec <- 1:4
arr[1, 2, 3, 4] # same as
do.call(`[`, c(list(arr), as.list(vec)))
But if the number of dimensions of the array is not fixed and can change
during the course of the prog I am stuck as to how to do this, as I don’t
know a way of feeding a vector or list of unspecified beforehand length
into the coordinates for an array
I can’t find anything useful about this on the net
Does anyone have any ideas?
Thanks, Nick
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Brian D. Ripley, rip...@stats.ox.ac.uk
Emeritus Professor of Applied Statistics, University of Oxford
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