refactor!: rewrite <DataFrame>$get_columns() (#991)

NEWS.md

@@ -64,6 +64,7 @@
     - The usage of `pl$date_range()` to create a range of `Datetime` data type is deprecated.
       `pl$date_range()` will always create a range of `Date` data type in the future.
       Please use `pl$datetime_range()` if you want to create a range of `Datetime` instead.
+    - `<DataFrame>$get_columns()` now returns an unnamed list instead of a named list (#991).
 
 - The argument `columns` in `$drop()` is removed. `$drop()` now accepts several
   character scalars, such as `$drop("a", "b", "c")` (#912).

R/dataframe__frame.R

@@ -598,16 +598,21 @@ DataFrame_clone = function() {
   .pr$DataFrame$clone_in_rust(self)
 }
 
-#' Get columns (as Series)
-#' @name DataFrame_get_columns
-#' @description Extract all DataFrame columns as a list of Polars series.
+#' Get the DataFrame as a List of Series
 #'
-#' @return A list of series
-#' @keywords  DataFrame
-#' @docType NULL
-#' @format NULL
+#' @return A list of [Series][Series_class]
+#' @seealso
+#' - [`<DataFrame>$to_list()`][DataFrame_to_list]:
+#'   Similar to this method but returns a list of vectors instead of [Series][Series_class].
 #' @examples
-#' df = pl$DataFrame(iris[1:2, ])
+#' df = pl$DataFrame(foo = 1L:3L, bar = 4L:6L)
+#' df$get_columns()
+#'
+#' df = pl$DataFrame(
+#'   a = 1:4,
+#'   b = c(0.5, 4, 10, 13),
+#'   c = c(TRUE, TRUE, FALSE, TRUE)
+#' )
 #' df$get_columns()
 DataFrame_get_columns = use_extendr_wrapper
 
@@ -969,7 +974,9 @@ DataFrame_to_data_frame = function(..., int64_conversion = polars_options()$int6
 #'
 #' @return R list of vectors
 #' @inheritSection DataFrame_class Conversion to R data types considerations
-#' @keywords DataFrame
+#' @seealso
+#' - [`<DataFrame>$get_columns()`][DataFrame_get_columns]:
+#'   Similar to this method but returns a list of [Series][Series_class] instead of vectors.
 #' @examples
 #' pl$DataFrame(iris)$to_list()
 DataFrame_to_list = function(unnest_structs = TRUE, ..., int64_conversion = polars_options()$int64_conversion) {

src/rust/src/rdataframe/mod.rs

@@ -196,14 +196,9 @@ impl RPolarsDataFrame {
     }
 
     pub fn get_columns(&self) -> List {
-        let mut l = List::from_values(
-            self.0
-                .get_columns()
-                .iter()
-                .map(|x| RPolarsSeries(x.clone())),
-        );
-        l.set_names(self.0.get_column_names()).unwrap();
-        l
+        let cols = self.0.get_columns().to_vec();
+        let vec = unsafe { std::mem::transmute::<Vec<pl::Series>, Vec<RPolarsSeries>>(cols) };
+        List::from_values(vec)
     }
 
     pub fn dtypes(&self) -> List {

tests/testthat/test-dataframe.R

@@ -369,7 +369,7 @@ test_that("get column(s)", {
   expected_list_of_series = {
     expected = lapply(
       1:5,
-      function(i) as_polars_series(iris[[i]],names(iris)[i])
+      function(i) as_polars_series(iris[[i]], names(iris)[i])
     )
     names(expected) = names(iris)
     expected
@@ -385,7 +385,7 @@ test_that("get column(s)", {
   list_of_vectors = lapply(actual_list_of_series, function(x) x$to_vector())
   expect_identical(
     list_of_vectors,
-    as.list(iris)
+    unname(as.list(iris))
   )
 })
 

tests/testthat/test-expr_expr.R

@@ -717,10 +717,7 @@ test_that("Expr_rechunk Series_chunk_lengths", {
   )$get_columns()
   expect_identical(
     lapply(series_list, \(x) x$chunk_lengths()),
-    list(
-      a_chunked = c(3, 3),
-      a_rechunked = 6
-    )
+    list(c(3, 3), 6)
   )
 })