Remove $to_struct() for Expr (#1092)

Co-authored-by: eitsupi <[email protected]>

NEWS.md

@@ -2,6 +2,13 @@
 
 ## Polars R Package (development version)
 
+### Breaking changes
+
+- `$to_struct()` on an Expr is removed. This method is now only available for
+  `Series`, `DataFrame`, and in the `$list` and `$arr` subnamespaces. For example,
+  `pl$col("a", "b", "c")$to_struct()` should be replaced with
+  `pl$struct(c("a", "b", "c"))` (#1092).
+
 ## Polars R Package 0.16.4
 
 ### New features

R/dataframe__frame.R

@@ -1127,8 +1127,8 @@ DataFrame_to_struct = function(name = "") {
 #'   c = 6:10
 #' )$
 #'   select(
-#'   pl$col("b")$to_struct(),
-#'   pl$col("a", "c")$to_struct()$alias("a_and_c")
+#'   pl$struct("b"),
+#'   pl$struct(c("a", "c"))$alias("a_and_c")
 #' )
 #' df
 #'

R/datatype.R

@@ -240,14 +240,14 @@ DataType_Duration = function(time_unit = "us") {
 #'   )
 #' }
 #'
-#' # Finally, one can use the method `$to_struct()` to convert existing columns
-#' # or `Series` to a `Struct`:
+#' # Finally, one can use `pl$struct()` to convert existing columns or `Series`
+#' # to a `Struct`:
 #' x = pl$DataFrame(
 #'   a = 1:2,
 #'   b = list(c("x", "y"), "z")
 #' )
 #'
-#' out = x$select(pl$col("a", "b")$to_struct())
+#' out = x$select(pl$struct(c("a", "b")))
 #' out
 #'
 #' out$schema

R/expr__expr.R

@@ -3199,17 +3199,6 @@ Expr_implode = use_extendr_wrapper
 #' df$with_columns(pl$all()$shrink_dtype()$name$suffix("_shrunk"))
 Expr_shrink_dtype = use_extendr_wrapper
 
-
-#' Convert an Expr to a Struct
-#' @return Expr
-#' @examples
-#' pl$DataFrame(iris[, 3:5])$with_columns(
-#'   my_struct = pl$all()$to_struct()
-#' )
-Expr_to_struct = function() {
-  pl$struct(self)
-}
-
 #' Convert Literal to Series
 #'
 #' Collect an expression based on literals into a Series.

R/lazyframe__lazy.R

@@ -1821,8 +1821,8 @@ LazyFrame_clone = function() {
 #'   c = 6:10
 #' )$
 #'   select(
-#'   pl$col("b")$to_struct(),
-#'   pl$col("a", "c")$to_struct()$alias("a_and_c")
+#'   pl$struct("b"),
+#'   pl$struct(c("a", "c"))$alias("a_and_c")
 #' )
 #' lf$collect()
 #'

tests/testthat/_snaps/after-wrappers.md

@@ -269,9 +269,9 @@
       [160] "str"               "struct"            "sub"              
       [163] "sum"               "tail"              "tan"              
       [166] "tanh"              "to_physical"       "to_r"             
-      [169] "to_series"         "to_struct"         "top_k"            
-      [172] "unique"            "unique_counts"     "upper_bound"      
-      [175] "value_counts"      "var"               "xor"              
+      [169] "to_series"         "top_k"             "unique"           
+      [172] "unique_counts"     "upper_bound"       "value_counts"     
+      [175] "var"               "xor"              
 
 ---
 
@@ -517,10 +517,10 @@
       [160] "std"               "str"               "struct"           
       [163] "sub"               "sum"               "tail"             
       [166] "tan"               "tanh"              "to_physical"      
-      [169] "to_r"              "to_series"         "to_struct"        
-      [172] "top_k"             "unique"            "unique_counts"    
-      [175] "upper_bound"       "value_counts"      "var"              
-      [178] "when"              "xor"              
+      [169] "to_r"              "to_series"         "top_k"            
+      [172] "unique"            "unique_counts"     "upper_bound"      
+      [175] "value_counts"      "var"               "when"             
+      [178] "xor"              
 
 ---
 
@@ -604,10 +604,10 @@
       [160] "std"               "str"               "struct"           
       [163] "sub"               "sum"               "tail"             
       [166] "tan"               "tanh"              "to_physical"      
-      [169] "to_r"              "to_series"         "to_struct"        
-      [172] "top_k"             "unique"            "unique_counts"    
-      [175] "upper_bound"       "value_counts"      "var"              
-      [178] "when"              "xor"              
+      [169] "to_r"              "to_series"         "top_k"            
+      [172] "unique"            "unique_counts"     "upper_bound"      
+      [175] "value_counts"      "var"               "when"             
+      [178] "xor"              
 
 ---
 
@@ -695,10 +695,9 @@
       [169] "sub"               "sum"               "tail"             
       [172] "tan"               "tanh"              "to_frame"         
       [175] "to_list"           "to_lit"            "to_physical"      
-      [178] "to_r"              "to_struct"         "to_vector"        
-      [181] "top_k"             "unique"            "unique_counts"    
-      [184] "upper_bound"       "value_counts"      "var"              
-      [187] "xor"              
+      [178] "to_r"              "to_vector"         "top_k"            
+      [181] "unique"            "unique_counts"     "upper_bound"      
+      [184] "value_counts"      "var"               "xor"              
 
 ---
 

tests/testthat/test-lazy.R

@@ -790,8 +790,8 @@ test_that("unnest", {
 
   df2 = df$
     select(
-    pl$col("a", "b", "c")$to_struct()$alias("first_struct"),
-    pl$col("d", "e", "f")$to_struct()$alias("second_struct")
+    pl$struct(c("a", "b", "c"))$alias("first_struct"),
+    pl$struct(c("d", "e", "f"))$alias("second_struct")
   )
 
   expect_identical(
@@ -804,7 +804,7 @@ test_that("unnest", {
     df$
       select(
       pl$col("a", "b", "c"),
-      pl$col("d", "e", "f")$to_struct()$alias("second_struct")
+      pl$struct(c("d", "e", "f"))$alias("second_struct")
     )$
       collect()$
       to_data_frame()