Also note that the functionality discussed could be regarded as a generalization of matrix multiplication where * and + are general functions and in this case we have * replaced by == and + replaced by &.
On Fri, Oct 11, 2019 at 10:46 AM Gabor Grothendieck <ggrothendi...@gmail.com> wrote: > > 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.email...@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]] > > > > ______________________________________________ > > R-devel@r-project.org mailing list > > https://stat.ethz.ch/mailman/listinfo/r-devel > > > > -- > Statistics & Software Consulting > GKX Group, GKX Associates Inc. > tel: 1-877-GKX-GROUP > email: ggrothendieck at gmail.com -- Statistics & Software Consulting GKX Group, GKX Associates Inc. tel: 1-877-GKX-GROUP email: ggrothendieck at gmail.com ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
