New matrix function
Using the example in the link here are two one-liners: A <- c(2,3,4,1,2,3,4,1,1,2) x <- c(1,2) # 1 - zoo library(zoo) which( rollapply(A, length(x), identical, x, fill = FALSE, align = "left") ) ## [1] 4 9 # 2 - Base R using conversion to character gregexpr(paste(x, collapse = ""), paste(A, collapse = ""))[[1]] ## [1] 4 9 ...snip ...
On Fri, Oct 11, 2019 at 3:45 AM Morgan Morgan <morgan.emailbox at gmail.com> wrote:
Hi All, I was looking for a function to find a small matrix inside a larger matrix in R similar to the one described in the following link: https://www.mathworks.com/matlabcentral/answers/194708-index-a-small-matrix-in-a-larger-matrix I couldn't find anything. The above function can be seen as a "generalisation" of the "which" function as well as the function described in the following post: https://coolbutuseless.github.io/2018/04/03/finding-a-length-n-needle-in-a-haystack/ Would be possible to add such a function to base R? I am happy to work with someone from the R core team (if you wish) and suggest an implementation in C. Thank you Best regards, Morgan [[alternative HTML version deleted]]
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