[R] Reversing one dimension of an array, in a generalized case
Roy Mendelssohn - NOAA Federal
roy.mendelssohn at noaa.gov
Thu Jun 1 18:51:47 CEST 2017
I have been looking for an elegant way to do the following, but haven't found it, I have never had a good understanding of any of the "apply" functions.
A simplified idea is I have an array, say:
junk(5, 10, 3)
where (5, 10, 3) give the dimension sizes, and I want to reverse the second dimension, so I could do:
junk1 <- junk[, rev(seq_len(10), ]
but what I am after is a general function that will do that where the array could be two, three or four dimensions, and I pass to the function which dimension I want to reverse, that is the function can not assume the number of dimensions of the array nor which dimension to reverse.
For example, if i try:
junk1 <- apply(junk, 2, rev)
junk1 comes out as two-dimensional, not three-dimensional.
It is probably something obvious but I am not getting it.
Thanks for any help.
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