[R] array - how to create "logical expression" for subset dynamically
Bert Gunter
bgunter.4567 at gmail.com
Mon Mar 6 00:43:37 CET 2017
A great example of why you need to read and follow the posting guide
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Cheers,
Bert
Bert Gunter
"The trouble with having an open mind is that people keep coming along
and sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
On Fri, Mar 3, 2017 at 9:59 AM, exponential <exponential at o2.pl> wrote:
> Hi! I've tried on SO, but without success. Maybe you will be able to help. I have the following array (I use 3-dimensional in this example for simplicity, but it can be 3+ dims - 10,11 or more): a <- c('a1', 'a2', 'a3') b <- c('bb', 'bbb') c <- c('C', 'CC', 'CCC') dimNa <- list('a' = a, 'b' = b, 'c' = c) outputArray <- array(NA, unname(sapply(dimNa, function(x) length(x), simplify = T)), unname(dimNa)) I can subset it using name from one dimension manually, like: > outputArray[,'bb',] C CC CCC a1 NA NA NA a2 NA NA NA a3 NA NA NA or > outputArray[,,'CCC'] bb bbb a1 NA NA a2 NA NA a3 NA NA I would like to write a function which subsets particular named element from one dimension (I mean I don't expect one dimension as a result by slicing using one named element, if that makes sense). Something like myfunc <- function(inputArray, namedElement) thus I can call it (using above example): myfunc(outputArray, 'bb') or myfunc(outputArray, 'CCC') to get identical as above results. I know how to deal with finding to which dimension "namedElement" belongs (in my case all names are unique). The question is how to subset it from the array? One idea is to construct what is inside [ ] (in example: ,'bb', or ,,'CCC'). I've tried something like this: inputDims <- ",,'CCC'" outputArray[parse(text=inputDi But this doesn't work. Maybe different approach should be used... Any ideas are welcome:)! Cheers!
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