feat: Add str$to_decimal()

R/000-wrappers.R

@@ -2644,6 +2644,12 @@ class(`PlRDataType`) <- c("PlRDataType__bundle", "savvy_neopolars__sealed")
   }
 }
 
+`PlRExpr_str_to_decimal` <- function(self) {
+  function(`infer_len`) {
+    .savvy_wrap_PlRExpr(.Call(savvy_PlRExpr_str_to_decimal__impl, `self`, `infer_len`))
+  }
+}
+
 `PlRExpr_str_contains` <- function(self) {
   function(`pat`, `literal`, `strict`) {
     `pat` <- .savvy_extract_ptr(`pat`, "PlRExpr")
@@ -3194,6 +3200,7 @@ class(`PlRDataType`) <- c("PlRDataType__bundle", "savvy_neopolars__sealed")
   e$`str_zfill` <- `PlRExpr_str_zfill`(ptr)
   e$`str_pad_end` <- `PlRExpr_str_pad_end`(ptr)
   e$`str_pad_start` <- `PlRExpr_str_pad_start`(ptr)
+  e$`str_to_decimal` <- `PlRExpr_str_to_decimal`(ptr)
   e$`str_contains` <- `PlRExpr_str_contains`(ptr)
   e$`str_ends_with` <- `PlRExpr_str_ends_with`(ptr)
   e$`str_starts_with` <- `PlRExpr_str_starts_with`(ptr)

R/expr-string.R

@@ -420,6 +420,27 @@ expr_str_zfill <- function(alignment) {
     wrap()
 }
 
+#' Convert a String column into a Decimal column
+#'
+#' @description
+#' This method infers the needed parameters `precision` and `scale`.
+#'
+#' @param inference_length Number of elements to parse to determine the
+#' `precision` and `scale`.
+#' @inherit as_polars_expr return
+#'
+#' @examples
+#' df <- pl$DataFrame(
+#'   numbers = c(
+#'     "40.12", "3420.13", "120134.19", "3212.98",
+#'     "12.90", "143.09", "143.9"
+#'   )
+#' )
+#' df$with_columns(numbers_decimal = pl$col("numbers")$str$to_decimal())
+expr_str_to_decimal <- function(inference_length = 100) {
+  self$`_rexpr`$str_to_decimal(inference_length) |>
+    wrap()
+}
 
 #' Left justify strings
 #'

src/init.c

@@ -2039,6 +2039,11 @@ SEXP savvy_PlRExpr_str_pad_start__impl(SEXP self__, SEXP c_arg__width, SEXP c_ar
     return handle_result(res);
 }
 
+SEXP savvy_PlRExpr_str_to_decimal__impl(SEXP self__, SEXP c_arg__infer_len) {
+    SEXP res = savvy_PlRExpr_str_to_decimal__ffi(self__, c_arg__infer_len);
+    return handle_result(res);
+}
+
 SEXP savvy_PlRExpr_str_contains__impl(SEXP self__, SEXP c_arg__pat, SEXP c_arg__literal, SEXP c_arg__strict) {
     SEXP res = savvy_PlRExpr_str_contains__ffi(self__, c_arg__pat, c_arg__literal, c_arg__strict);
     return handle_result(res);
@@ -2917,6 +2922,7 @@ static const R_CallMethodDef CallEntries[] = {
     {"savvy_PlRExpr_str_zfill__impl", (DL_FUNC) &savvy_PlRExpr_str_zfill__impl, 2},
     {"savvy_PlRExpr_str_pad_end__impl", (DL_FUNC) &savvy_PlRExpr_str_pad_end__impl, 3},
     {"savvy_PlRExpr_str_pad_start__impl", (DL_FUNC) &savvy_PlRExpr_str_pad_start__impl, 3},
+    {"savvy_PlRExpr_str_to_decimal__impl", (DL_FUNC) &savvy_PlRExpr_str_to_decimal__impl, 2},
     {"savvy_PlRExpr_str_contains__impl", (DL_FUNC) &savvy_PlRExpr_str_contains__impl, 4},
     {"savvy_PlRExpr_str_ends_with__impl", (DL_FUNC) &savvy_PlRExpr_str_ends_with__impl, 2},
     {"savvy_PlRExpr_str_starts_with__impl", (DL_FUNC) &savvy_PlRExpr_str_starts_with__impl, 2},

src/rust/api.h

@@ -409,6 +409,7 @@ SEXP savvy_PlRExpr_str_strip_chars_start__ffi(SEXP self__, SEXP c_arg__matches);
 SEXP savvy_PlRExpr_str_zfill__ffi(SEXP self__, SEXP c_arg__alignment);
 SEXP savvy_PlRExpr_str_pad_end__ffi(SEXP self__, SEXP c_arg__width, SEXP c_arg__fillchar);
 SEXP savvy_PlRExpr_str_pad_start__ffi(SEXP self__, SEXP c_arg__width, SEXP c_arg__fillchar);
+SEXP savvy_PlRExpr_str_to_decimal__ffi(SEXP self__, SEXP c_arg__infer_len);
 SEXP savvy_PlRExpr_str_contains__ffi(SEXP self__, SEXP c_arg__pat, SEXP c_arg__literal, SEXP c_arg__strict);
 SEXP savvy_PlRExpr_str_ends_with__ffi(SEXP self__, SEXP c_arg__sub);
 SEXP savvy_PlRExpr_str_starts_with__ffi(SEXP self__, SEXP c_arg__sub);

src/rust/src/expr/string.rs

@@ -80,6 +80,11 @@ impl PlRExpr {
         Ok(self.inner.clone().str().pad_start(width, fillchar).into())
     }
 
+    fn str_to_decimal(&self, infer_len: NumericScalar) -> Result<Self> {
+        let infer_len = <Wrap<usize>>::try_from(infer_len)?.0;
+        Ok(self.inner.clone().str().to_decimal(infer_len).into())
+    }
+
     fn str_contains(&self, pat: &PlRExpr, literal: bool, strict: bool) -> Result<Self> {
         if literal {
             Ok(self

tests/testthat/test-expr-string.R

@@ -1008,3 +1008,19 @@ test_that("$str$extract_many works", {
     pl$DataFrame(values = list("disco", c("rhap", "ody")))
   )
 })
+
+# TODO: uncomment when https://github.com/pola-rs/polars/issues/20556 is solved
+# test_that("to_decimal", {
+#   df <- pl$DataFrame(
+#     x = c(
+#       "40.12", "3420.13", "120134.19", "3212.98",
+#       "12.90", "143.09", "143.9"
+#     )
+#   )
+#   expect_equal(
+#     df$select(pl$col("x")$str$to_decimal()),
+#     pl$DataFrame(x = c(
+#       40.12, 3420.13, 120134.19, 3212.98, 12.90, 143.09, 143.9
+#     ), .schema_overrides = list(x = pl$Decimal(scale = 2)))
+#   )
+# })