Mostly finalizing (#628).

Author: SebKrantz

NEWS.md

@@ -10,7 +10,10 @@
 
 ### Bug Fixes
 
-* Fixed some issues using *collapse* and the *tidyverse* together, particularly regarding tidyverse methods for 'grouped_df' - thanks @NicChr (#645) .
+* Fixed some issues using *collapse* and the *tidyverse* together, particularly regarding tidyverse methods for 'grouped_df' - thanks @NicChr (#645).
+
+* More consistent handling of zero-length inputs - they are now also returned in `fmean()` and `fmedian()`/`fnth()` instead of returning `NA` (#628).
+
 
 ### Additions
 

src/fnth_fmedian_fquantile.c

@@ -1233,7 +1233,7 @@ SEXP fnthC(SEXP x, SEXP p, SEXP g, SEXP w, SEXP Rnarm, SEXP Rret, SEXP Rnthreads
   CHECK_PROB(l);
 
   // if(l < 1) return x;
-  if(l < 1 || (l == 1 && nullw)) return TYPEOF(x) == REALSXP ? x : ScalarReal(asReal(x));
+  if(l < 1 || (l == 1 && nullw)) return TYPEOF(x) == REALSXP ? x : l < 1 ? allocVector(REALSXP, 0) : ScalarReal(asReal(x));
 
   // First the simplest case
   if(nullg && nullw && nullo) return nth_impl(x, narm, ret, Q);

tests/testthat/test-miscellaneous-issues.R

@@ -225,12 +225,11 @@ test_that("0-length vectors give expected output", {
   funs <- .c(fsum, fprod, fmean, fmedian, fmin, fmax, fnth, fcumsum, fbetween, fwithin, fscale)
   for(i in funs) {
     FUN <- match.fun(i)
-    if(i %!in% .c(fsum, fmin, fmax, fcumsum, fmedian, fnth)) {
+    if(i %!in% .c(fsum, fmin, fmax, fcumsum)) {
       expect_true(all_identical(FUN(numeric(0)), FUN(integer(0)), numeric(0)))
     } else {
       expect_identical(FUN(numeric(0)), numeric(0))
-      if(i %in% .c(fmean, fprod, fnth, fmedian)) expect_identical(FUN(integer(0)), NA_real_)
-      else expect_identical(FUN(integer(0)), integer(0))
+      expect_identical(FUN(integer(0)), integer(0))
     }
   }
   funs <- .c(fmode, ffirst, flast)