tests, docs

NEWS.md

@@ -114,6 +114,7 @@
 - New methods `$select_seq()` and `$with_columns_seq()` for `DataFrame` and
   `LazyFrame` (#1003).
 - New method `$clear()` for `DataFrame`, `LazyFrame`, and `Series` (#1004).
+- New method `$struct$unnest()` for `Series` (#1010).
 
 ### Bug fixes
 

R/series__series.R

@@ -271,6 +271,14 @@ Series_struct = method_as_active_binding(
       fields = method_as_active_binding(function() {
         unwrap(.pr$Series$struct_fields(pl_series), "in $struct$fields:")
       }),
+      #' Convert this struct Series to a DataFrame with a separate column for
+      #' each field
+      #'
+      #' @name Series_struct_unnest
+      #' @return A DataFrame
+      #' @examples
+      #' s = pl$Series(values = c(1, 2), dtype = pl$Struct(foo = pl$Float64))
+      #' s$struct$unnest()
       unnest = function() {
         .pr$Series$struct_unnest(pl_series) |>
           unwrap("in $struct$unnest():")

tests/testthat/_snaps/after-wrappers.md

@@ -717,10 +717,11 @@
       [37] "rep"                         "set_sorted_mut"             
       [39] "shape"                       "sleep"                      
       [41] "sort_mut"                    "std"                        
-      [43] "struct_fields"               "sub"                        
-      [45] "sum"                         "to_fmt_char"                
-      [47] "to_frame"                    "to_r"                       
-      [49] "value_counts"                "var"                        
+      [43] "struct_fields"               "struct_unnest"              
+      [45] "sub"                         "sum"                        
+      [47] "to_fmt_char"                 "to_frame"                   
+      [49] "to_r"                        "value_counts"               
+      [51] "var"                        
 
 # public and private methods of each class RThreadHandle
 

tests/testthat/test-series.R

@@ -679,3 +679,17 @@ test_that("$clear() works", {
     "greater or equal to 0"
   )
 })
+
+test_that("$struct$unnest() works", {
+  s = pl$Series(values = c(1, 2), dtype = pl$Struct(foo = pl$Float64))
+  expect_identical(
+    s$struct$unnest()$to_list(),
+    list(foo = c(1, 2))
+  )
+  # empty Series
+  s = pl$Series(dtype = pl$Struct(foo = pl$Float64))
+  expect_identical(
+    s$struct$unnest()$to_list(),
+    list(foo = numeric(0))
+  )
+})