From f4b0d8d33e45c8587e1009b2ca0d3065105b8f17 Mon Sep 17 00:00:00 2001
From: Etienne Bacher <52219252+etiennebacher@users.noreply.github.com>
Date: Thu, 6 Jun 2024 15:18:30 +0100
Subject: [PATCH] Change default value for `strategy` in `$n_chunks()` (#1137)

---
 NEWS.md                         |  4 ++++
 R/dataframe__frame.R            |  2 +-
 man/DataFrame_n_chunks.Rd       |  2 +-
 tests/testthat/test-concat.R    |  4 ++--
 tests/testthat/test-dataframe.R | 14 +++++++-------
 5 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/NEWS.md b/NEWS.md
index e886f5f24..2a41befa2 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -2,6 +2,10 @@
 
 ## Polars R Package (development version)
 
+### Breaking changes
+
+- In `$n_chunks()`, the default value of `strategy` now is `"first"` (#1137).
+
 ### New features
 
 - New method `$has_nulls()` (#1133).
diff --git a/R/dataframe__frame.R b/R/dataframe__frame.R
index 4f63e17c5..a8f291704 100644
--- a/R/dataframe__frame.R
+++ b/R/dataframe__frame.R
@@ -1215,7 +1215,7 @@ DataFrame_first = function() {
 #' str(z)
 #' z = rechunk(z)
 #' str(z)
-DataFrame_n_chunks = function(strategy = "all") {
+DataFrame_n_chunks = function(strategy = "first") {
   .pr$DataFrame$n_chunks(self, strategy) |>
     unwrap("in n_chunks():")
 }
diff --git a/man/DataFrame_n_chunks.Rd b/man/DataFrame_n_chunks.Rd
index 4fe2e50cc..6fd3335fb 100644
--- a/man/DataFrame_n_chunks.Rd
+++ b/man/DataFrame_n_chunks.Rd
@@ -4,7 +4,7 @@
 \alias{DataFrame_n_chunks}
 \title{Number of chunks of the Series in a DataFrame}
 \usage{
-DataFrame_n_chunks(strategy = "all")
+DataFrame_n_chunks(strategy = "first")
 }
 \arguments{
 \item{strategy}{Either \code{"all"} or \code{"first"}. \code{"first"} only returns chunks
diff --git a/tests/testthat/test-concat.R b/tests/testthat/test-concat.R
index 1803d2559..4b680a86b 100644
--- a/tests/testthat/test-concat.R
+++ b/tests/testthat/test-concat.R
@@ -58,8 +58,8 @@ test_that("concat dataframe", {
   )
 
   # check rechunk works
-  expect_identical(pl$concat(mtcars, mtcars, rechunk = TRUE)$n_chunks(), rep(1, 11))
-  expect_identical(pl$concat(mtcars, mtcars, rechunk = FALSE)$n_chunks(), rep(2, 11))
+  expect_identical(pl$concat(mtcars, mtcars, rechunk = TRUE)$n_chunks("all"), rep(1, 11))
+  expect_identical(pl$concat(mtcars, mtcars, rechunk = FALSE)$n_chunks("all"), rep(2, 11))
 
 
 
diff --git a/tests/testthat/test-dataframe.R b/tests/testthat/test-dataframe.R
index b42dc77f5..c2a5331e4 100644
--- a/tests/testthat/test-dataframe.R
+++ b/tests/testthat/test-dataframe.R
@@ -948,15 +948,15 @@ test_that("n_chunks", {
     how = "horizontal"
   )
 
-  expect_identical(df$n_chunks(), c(1, 2))
-  expect_identical(df$n_chunks("first"), c(1))
+  expect_identical(df$n_chunks("all"), c(1, 2))
+  expect_identical(df$n_chunks(), 1)
+  expect_identical(pl$DataFrame()$n_chunks("all"), numeric())
   expect_identical(pl$DataFrame()$n_chunks(), numeric())
-  expect_identical(pl$DataFrame()$n_chunks("first"), numeric())
 
-  pl$DataFrame()$n_chunks("wrong strat") |>
-    get_err_ctx("Plain") |>
-    grepl(pat = "strategy") |>
-    expect_true()
+  expect_grepl_error(
+    pl$DataFrame()$n_chunks("wrong strat"),
+    "strategy not recognized"
+  )
 })