Guard against unsupported operations in exact_resample

References #59

Author: dbaston

R/exact_resample.R

@@ -45,6 +45,14 @@ setMethod('exact_resample',
               }
             }
 
+            if (length(fun) != 1) {
+              stop("Only a single operation may be used for resampling.")
+            }
+
+            if (startsWith(fun, 'weighted')) {
+              stop("Weighted operations cannot be used for resampling.")
+            }
+
             x <- raster::readStart(x)
             tryCatch({
               CPP_resample(x, y, fun)

src/RcppExports.cpp

@@ -5,6 +5,11 @@
 
 using namespace Rcpp;
 
+#ifdef RCPP_USE_GLOBAL_ROSTREAM
+Rcpp::Rostream<true>&  Rcpp::Rcout = Rcpp::Rcpp_cout_get();
+Rcpp::Rostream<false>& Rcpp::Rcerr = Rcpp::Rcpp_cerr_get();
+#endif
+
 // CPP_coverage_fraction
 Rcpp::S4 CPP_coverage_fraction(Rcpp::S4& rast, const Rcpp::RawVector& wkb, bool crop);
 RcppExport SEXP _exactextractr_CPP_coverage_fraction(SEXP rastSEXP, SEXP wkbSEXP, SEXP cropSEXP) {

src/resample.cpp

@@ -56,10 +56,6 @@ Rcpp::S4 CPP_resample(Rcpp::S4 & rast_in,
     Rcpp::Function rasterFn = raster["raster"];
     Rcpp::Function valuesFn = raster["values<-"];
 
-    if (stat.size() != 1) {
-      Rcpp::stop("Only a single operation may be used for resampling.");
-    }
-
     S4RasterSource rsrc(rast_in);
 
     Rcpp::S4 out = rasterFn(rast_out);

tests/testthat/test_exact_resample.R

@@ -51,6 +51,16 @@ test_that("error thrown if multiple stats provided", {
     'Only a single')
 })
 
+test_that("error thrown if weighted stat provided", {
+  r <- raster::raster(resolution = 2)
+  target <- raster::shift(r, 2.5, 1)
+
+  expect_error(
+    exact_resample(r, target, fun = "weighted_mean"),
+    'cannot be used for resampling'
+  )
+})
+
 test_that("error thrown if rasters have different CRS", {
   src <- make_square_raster(1:100, crs='+init=epsg:4326')
   dst <- make_square_raster(1:100, crs='+init=epsg:4269')