Add bindings for round function

R/pkg-arrow.R

@@ -291,6 +291,17 @@ arrow_funs[["grepl"]] <- function(pattern, x, ...) {
   substrait_call("string.contains", x, pattern)
 }
 
+# rounding functions
+arrow_funs[["round"]] <- function(x, digits = 0) {
+  substrait_call(
+    "rounding.round",
+    x,
+    digits,
+    .options = list(
+      substrait$FunctionOption$create(name = "rounding",preference = "TIE_TO_EVEN"))
+    )
+}
+
 check_na_rm <- function(na.rm) {
   if (!na.rm) {
     warning("Missing value removal from aggregate functions not yet supported, switching to na.rm = TRUE")

R/pkg-duckdb.R

@@ -294,6 +294,16 @@ duckdb_funs[["n_distinct"]] <- function(x, na.rm = FALSE) {
   substrait_call_agg("approx_count_distinct", x, .output_type = substrait_i64())
 }
 
+duckdb_funs[["round"]] <- function(x, digits = 0) {
+  substrait_call(
+    "round",
+    x,
+    as.integer(digits),
+    .options = list(
+      substrait$FunctionOption$create(name = "rounding",preference = "TIE_TO_EVEN"))
+    )
+}
+
 check_na_rm_duckdb <- function(na.rm) {
   if (!na.rm) {
     warning("Missing value removal from aggregate functions not supported in DuckDB, switching to na.rm = TRUE")

tests/testthat/test-pkg-arrow.R

@@ -662,3 +662,22 @@ test_that("arrow translation for if_else() works", {
     )
   )
 })
+
+test_that("arrow translation for round works", {
+  skip_if_not(has_arrow_with_substrait())
+
+  # Error: NotImplemented: conversion to arrow::DataType from Substrait type
+  # /home/nic2/arrow/cpp/src/arrow/engine/substrait/expression_internal.cc:119  FromProto(scalar_fn.output_type(), ext_set, conversion_options)
+  # /home/nic2/arrow/cpp/src/arrow/engine/substrait/expression_internal.cc:317  DecodeScalarFunction(function_id, scalar_fn, ext_set, conversion_options)
+  # /home/nic2/arrow/cpp/src/arrow/engine/substrait/relation_internal.cc:548  FromProto(expr, ext_set, conversion_options)
+  # /home/nic2/arrow/cpp/src/arrow/engine/substrait/serde.cc:157  FromProto(plan_rel.has_root() ? plan_rel.root().input() : plan_rel.rel(), ext_set, conversion_options)
+  expect_equal(
+    tibble::tibble(x = c(1, 2.34, 3.456, 4.5)) %>%
+      arrow_substrait_compiler() %>%
+      substrait_project(y = round(x)) %>%
+      dplyr::collect(),
+    tibble::tibble(
+      y = c(1, 2, 3, 4)
+    )
+  )
+})

tests/testthat/test-pkg-duckdb.R

@@ -355,3 +355,19 @@ test_that("duckdb translation for n_distinct works", {
     classes = "substrait.n_distinct.approximate"
   )
 })
+
+test_that("duckdb translation for round works", {
+  skip_if_not(has_duckdb_with_substrait())
+
+  # DuckDB is ignoring the rounding strategy - need to check if it even can implement
+  # alternatives? Should we just do this one but warn??
+  expect_equal(
+    tibble::tibble(x = c(1, 2.34, 3.456, 4.5)) %>%
+      duckdb_substrait_compiler() %>%
+      substrait_project(x, y = round(x)) %>%
+      dplyr::collect(),
+    tibble::tibble(
+      y = c(1, 2, 3, 4)
+    )
+  )
+})