From acdeecea0d37b1d364e1fc33d481ebb975de5f08 Mon Sep 17 00:00:00 2001
From: Michael Mayer <mayermichael79@gmail.com>
Date: Sat, 7 Dec 2024 09:02:48 +0100
Subject: [PATCH] Workaround around the problem of formula.tools

---
 DESCRIPTION                  |  2 +-
 NEWS.md                      |  7 +++++++
 R/missRanger.R               | 17 +++++++++++++----
 packaging.R                  |  2 +-
 tests/testthat/test-helper.R |  8 ++++++++
 5 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/DESCRIPTION b/DESCRIPTION
index f9cde66..7191c25 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,6 +1,6 @@
 Package: missRanger
 Title: Fast Imputation of Missing Values
-Version: 2.6.0
+Version: 2.6.1
 Authors@R: 
     person("Michael", "Mayer", , "mayermichael79@gmail.com", role = c("aut", "cre"))
 Description: Alternative implementation of the beautiful 'MissForest'
diff --git a/NEWS.md b/NEWS.md
index c958b21..bed8842 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,3 +1,10 @@
+# missRanger 2.6.1
+
+### Improvement
+
+Solves an incompatibility with the {formula.tools} package. `formula.tools:::as.character.formula()` breaks `base::as.character()` for formulas, which prevented {missRanger} from working, see also
+https://github.com/decisionpatterns/formula.tools/issues/11. We have added a workaround in [#81](https://github.com/mayer79/missRanger/pull/81).
+
 # missRanger 2.6.0
 
 ### Major bug fix
diff --git a/R/missRanger.R b/R/missRanger.R
index e94febe..f5a5a6a 100644
--- a/R/missRanger.R
+++ b/R/missRanger.R
@@ -426,11 +426,20 @@ missRanger <- function(
   if (!inherits(formula, "formula")) {
     stop("'formula' should be a formula!")
   }
-  formula <- as.character(formula)
-  if (length(formula) != 3L) {
-    stop("Formula must have left and right hand side. If it has: Don't load {formula.tools}. It breaks base R's as.character()")
+  out <- as.character(formula)
+  if (length(out) == 1L) {
+    # {formula.tools} seems to be loaded, which breaks base's as.character().
+    # This is a workaround.
+    out <- strsplit(out, "~", fixed = TRUE)[[1L]]
+    if (any(out == "")) {
+      stop("Formula must have left and right hand side.")
+    }
+    out <- c("~", out)
+  }
+  if (length(out) != 3L) {
+    stop("Formula must have left and right hand side.")
   }
-  return(lapply(formula[2:3], FUN = .string_parser, data = data))
+  return(lapply(out[2:3], FUN = .string_parser, data = data))
 }
 
 # Checks if response type can be used in ranger (or easily converted to)
diff --git a/packaging.R b/packaging.R
index 6c0183f..664f379 100644
--- a/packaging.R
+++ b/packaging.R
@@ -15,7 +15,7 @@ library(usethis)
 use_description(
   fields = list(
     Title = "Fast Imputation of Missing Values",
-    Version = "2.6.0",
+    Version = "2.6.1",
     Description = "Alternative implementation of the beautiful 'MissForest' algorithm used to impute 
     mixed-type data sets by chaining random forests, introduced by Stekhoven, D.J. and 
     Buehlmann, P. (2012) <doi:10.1093/bioinformatics/btr597>. Under the hood, it uses the 
diff --git a/tests/testthat/test-helper.R b/tests/testthat/test-helper.R
index 7562f24..d946263 100644
--- a/tests/testthat/test-helper.R
+++ b/tests/testthat/test-helper.R
@@ -31,6 +31,14 @@ test_that(".formula_parser() works", {
     .formula_parser(. - Species ~ . - Species - Sepal.Length, data = iris),
     list(names(iris[1:4]), names(iris[2:4]))
   )
+  
+  # Non-syntactic name
+  ir <- iris
+  colnames(ir)[1] <- "a b"
+  expect_equal(
+    .formula_parser(Sepal.Width ~ . - Petal.Length - Petal.Width - Species, ir),
+    list("Sepal.Width", c("a b", "Sepal.Width"))
+  )
 })
 
 test_that(".check_response() works", {