Improvements to lag2_ and possible bug fixes.

R/lag.R

@@ -30,7 +30,8 @@
 #' @details
 #' For most applications, it is more efficient and recommended to use `lag_()`.
 #' For anything that requires dynamic lags, lag by order of another variable,
-#' or by-group lags, one can use `lag2_()`.
+#' or by-group lags, one can use `lag2_()`. \cr
+#' To do cyclic lags, see the examples below for an implementation.
 #'
 #' ### `lag2_`
 #'
@@ -99,8 +100,8 @@
 #' # lag every 2nd element
 #' lag2_(x, n = c(1, 0)) # lag vector is recycled
 #'
-#' # Explicit lags along x
-#' lags <- lag_sequence(length(x), 1, partial = FALSE)
+#' # Explicit Lag(3) using a vector of lags
+#' lags <- lag_sequence(length(x), 3, partial = FALSE)
 #' lag2_(x, n = lags)
 #'
 #' # Alternating lags and leads
@@ -124,12 +125,13 @@
 #'
 #' # Example of how to do a cyclical lag
 #' n <- length(x)
+#'
+#' # When k >= 0
 #' k <- min(3, n)
-#' if (k >= 0){
-#'   lag2_(x, c(rep(-n + k, k), rep(k, n - k)))
-#' } else {
-#'   lag2_(x, c(rep(k, n + k), rep(n + k, -k)))
-#' }
+#' lag2_(x, c(rep(-n + k, k), rep(k, n - k)))
+#' # When k < 0
+#' k <- max(-3, -n)
+#' lag2_(x, c(rep(k, n + k), rep(n + k, -k)))
 #'
 #' # As it turns out, we can do a grouped lag
 #' # by supplying group sizes as run lengths and group order as the order
@@ -185,13 +187,15 @@
 #' # Let's compare this to data.table
 #'
 #' library(data.table)
-#' setDTthreads(2)
+#' default_threads <- getDTthreads()
+#' setDTthreads(1)
 #' dt <- data.table(x = 1:10^5,
 #'                  g = sample.int(10^4, 10^5, TRUE))
 #'
 #' bench::mark(dt[, y := shift(x), by = g][][["y"]],
 #'             grouped_lag(dt$x, g = dt$g),
 #'             iterations = 10)
+#' setDTthreads(default_threads)
 #' @rdname lag
 #' @export
 lag_ <- function(x, n = 1L, fill = NULL, set = FALSE, recursive = TRUE){
@@ -202,8 +206,3 @@ lag_ <- function(x, n = 1L, fill = NULL, set = FALSE, recursive = TRUE){
 lag2_ <- function(x, n = 1L, order = NULL, run_lengths = NULL, fill = NULL, recursive = TRUE){
   .Call(`_cheapr_cpp_lag2`, x, n, order, run_lengths, fill, recursive)
 }
-# lag2_ <- function(x, n = 1L, order = if (recursive && is.data.frame(x)) seq_len(nrow(x)) else seq_along(x),
-#                   run_lengths = if (recursive && is.data.frame(x)) nrow(x) else length(x),
-#                   fill = NULL, recursive = TRUE){
-#   .Call(`_cheapr_cpp_lag2`, x, n, order, run_lengths, fill, recursive)
-# }

src/cpp11.cpp

@@ -90,10 +90,10 @@ extern "C" SEXP _cheapr_cpp_lcm2_vectorised(SEXP x, SEXP y, SEXP tol, SEXP na_rm
   END_CPP11
 }
 // lag.cpp
-SEXP cpp_lag(SEXP x, int k, SEXP fill, bool set, bool recursive);
+SEXP cpp_lag(SEXP x, R_xlen_t k, SEXP fill, bool set, bool recursive);
 extern "C" SEXP _cheapr_cpp_lag(SEXP x, SEXP k, SEXP fill, SEXP set, SEXP recursive) {
   BEGIN_CPP11
-    return cpp11::as_sexp(cpp_lag(cpp11::as_cpp<cpp11::decay_t<SEXP>>(x), cpp11::as_cpp<cpp11::decay_t<int>>(k), cpp11::as_cpp<cpp11::decay_t<SEXP>>(fill), cpp11::as_cpp<cpp11::decay_t<bool>>(set), cpp11::as_cpp<cpp11::decay_t<bool>>(recursive)));
+    return cpp11::as_sexp(cpp_lag(cpp11::as_cpp<cpp11::decay_t<SEXP>>(x), cpp11::as_cpp<cpp11::decay_t<R_xlen_t>>(k), cpp11::as_cpp<cpp11::decay_t<SEXP>>(fill), cpp11::as_cpp<cpp11::decay_t<bool>>(set), cpp11::as_cpp<cpp11::decay_t<bool>>(recursive)));
   END_CPP11
 }
 // lag.cpp

src/gcd.cpp

@@ -161,7 +161,7 @@ SEXP cpp_lcm(SEXP x, double tol, bool na_rm){
       lcm = NA_REAL;
     }
     int lcm_int = p_x[0];
-    double int_max = double(integer_max_);
+    double int_max = integer_max_;
     for (int i = 1; i < n; ++i) {
       if (!na_rm && !(lcm == lcm)){
         lcm = NA_REAL;