Francisco, On 5 January 2021 at 13:58, Francisco Bischoff wrote: | First of all, let me thank all involved with the Rcpp package! | | I just have a (maybe silly) question, but I struggle with this frequently | in my codes: | | Range() vs IntegerVector | | One example is when I need a reverse index, like R's 10:1, so I had to | write my own function that returns an IntegerVector. But, to work I have to | do this ugly code: | | IntegerVector dot_rev_idxs1 = ::seq((i - 1), beginidx); | IntegerVector dot_rev_idxs2 = ::seq((idx_nn - 1), (beginidx + | idx_diff)); | IntegerVector dot_rev_idxs3 = ::seq((i - 1 + window_size), ( | beginidx + window_size)); | IntegerVector dot_rev_idxs4 = ::seq((idx_nn - 1 + window_size), ( | beginidx + idx_diff + window_size)); | dotproduct[dot_rev_idxs1] = (NumericVector)((NumericVector)cumsum( | data[dot_rev_idxs1] * data[dot_rev_idxs2] - | | data[dot_rev_idxs3] * data[dot_rev_idxs4]) + | dotproduct[i]); | | I frequently have to cast the results with (NumericVector)... | | This also happens using Range(). But there is a difference if I use Range() | this way: my_vector[Range(0,10)]; or Range range = Range(0, | 10); my_vector[range]; | | How is the proper way to deal with it?
I am not sure I fully understand what it is that you try to and what you are struggling with. Could you construct a small self-contained example? | Other question: as<NumericVector() doesn't 'cast' right? Does it try to | 'convert' formats? | | And finally, I see that Matlab has a unique way to deal with ranges: | | Ex.: | | 1) (1:10) --> 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 | 2) (10:1) --> returns a vector with size zero | 3) (10:-1:1) --> 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 | | Range() shouldn't at least reproduce the R's counterpart and accept Range(10,1) | == 10:1? We could probably generalize seq() to count down from 'high' to 'low'. Pull requests welcome... Dirk -- https://dirk.eddelbuettel.com | @eddelbuettel | e...@debian.org _______________________________________________ Rcpp-devel mailing list Rcpp-devel@lists.r-forge.r-project.org https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
