fix

NAMESPACE

@@ -332,6 +332,8 @@ S3method(find_terms,aovlist)
 S3method(find_terms,bfsl)
 S3method(find_terms,default)
 S3method(find_terms,mipo)
+S3method(find_transformation,character)
+S3method(find_transformation,default)
 S3method(find_weights,brmsfit)
 S3method(find_weights,default)
 S3method(find_weights,gls)

R/find_transformation.R

@@ -8,7 +8,9 @@
 #'   `log(x+<number>)`, `log-log`, `power` (to 2nd power, like `I(x^2)`), and
 #'   `inverse` (like `1/y`).
 #'
-#' @param x A regression model.
+#' @param x A regression model or a character string of the response value.
+#' @param ... Currently not used.
+#'
 #' @return A string, with the name of the function of the applied transformation.
 #'   Returns `"identity"` for no transformation, and e.g. `"log(x+3)"` when
 #'   a specific values was added to the response variables before
@@ -26,32 +28,48 @@
 #' # log+2
 #' model <- lm(log(Sepal.Length + 2) ~ Species, data = iris)
 #' find_transformation(model)
+#'
+#' # inverse, response provided as character string
+#' find_transformation("1 / y")
+#' @export
+find_transformation <- function(x, ...) {
+  UseMethod("find_transformation")
+}
+
+
 #' @export
-find_transformation <- function(x) {
+find_transformation.default <- function(x, ...) {
   # validation check
   if (is.null(x) || is.data.frame(x) || !is_model(x)) {
     return(NULL)
   }
-
   rv <- find_terms(x)[["response"]]
+  find_transformation(rv)
+}
+
+
+#' @export
+find_transformation.character <- function(x, ...) {
   transform_fun <- "identity"
 
+  # remove whitespaces
+  x <- gsub(" ", "", x, fixed = TRUE)
 
   # log-transformation
 
-  if (any(grepl("log\\((.*)\\)", rv))) {
+  if (any(grepl("log\\((.*)\\)", x))) {
     # do we have log-log models?
-    if (grepl("log\\(log\\((.*)\\)\\)", rv)) {
+    if (grepl("log\\(log\\((.*)\\)\\)", x)) {
       transform_fun <- "log-log"
     } else {
       # 1. try: log(x + number)
       plus_minus <- .safe(
-        eval(parse(text = gsub("log\\(([^,\\+)]*)(.*)\\)", "\\2", rv)))
+        eval(parse(text = gsub("log\\(([^,\\+)]*)(.*)\\)", "\\2", x)))
       )
       # 2. try: log(number + x)
       if (is.null(plus_minus)) {
         plus_minus <- .safe(
-          eval(parse(text = gsub("log\\(([^,\\+)]*)(.*)\\)", "\\1", rv)))
+          eval(parse(text = gsub("log\\(([^,\\+)]*)(.*)\\)", "\\1", x)))
         )
       }
       if (is.null(plus_minus)) {
@@ -65,40 +83,40 @@ find_transformation <- function(x) {
 
   # log1p-transformation
 
-  if (any(grepl("log1p\\((.*)\\)", rv))) {
+  if (any(grepl("log1p\\((.*)\\)", x))) {
     transform_fun <- "log1p"
   }
 
 
   # expm1-transformation
 
-  if (any(grepl("expm1\\((.*)\\)", rv))) {
+  if (any(grepl("expm1\\((.*)\\)", x))) {
     transform_fun <- "expm1"
   }
 
 
   # log2/log10-transformation
 
-  if (any(grepl("log2\\((.*)\\)", rv))) {
+  if (any(grepl("log2\\((.*)\\)", x))) {
     transform_fun <- "log2"
   }
 
-  if (any(grepl("log10\\((.*)\\)", rv))) {
+  if (any(grepl("log10\\((.*)\\)", x))) {
     transform_fun <- "log10"
   }
 
 
   # exp-transformation
 
-  if (any(grepl("exp\\((.*)\\)", rv))) {
+  if (any(grepl("exp\\((.*)\\)", x))) {
     transform_fun <- "exp"
   }
 
 
   # sqrt-transformation
 
-  if (any(grepl("sqrt\\((.*)\\)", rv))) {
-    plus_minus <- eval(parse(text = gsub("sqrt\\(([^,\\+)]*)(.*)\\)", "\\2", rv)))
+  if (any(grepl("sqrt\\((.*)\\)", x))) {
+    plus_minus <- eval(parse(text = gsub("sqrt\\(([^,\\+)]*)(.*)\\)", "\\2", x)))
     if (is.null(plus_minus)) {
       transform_fun <- "sqrt"
     } else {
@@ -109,21 +127,21 @@ find_transformation <- function(x) {
 
   # inverse-transformation
 
-  if (any(startsWith(rv, "1/"))) {
+  if (any(startsWith(x, "1/"))) {
     transform_fun <- "inverse"
   }
 
 
   # (unknown) I-transformation
 
-  if (any(grepl("I\\((.*)\\)", rv))) {
+  if (any(grepl("I\\((.*)\\)", x))) {
     transform_fun <- NULL
   }
 
 
   # power-transformation
 
-  if (any(grepl("(.*)(\\^|\\*\\*)\\s?-?(\\d+|[()])", rv))) {
+  if (any(grepl("(.*)(\\^|\\*\\*)\\s?-?(\\d+|[()])", x))) {
     transform_fun <- "power"
   }
 

tests/testthat/test-find_transformation.R

@@ -6,6 +6,7 @@ test_that("find_transformation - identity", {
 test_that("find_transformation - log", {
   model <- lm(log(Sepal.Length) ~ Species, data = iris)
   expect_identical(find_transformation(model), "log")
+  expect_identical(find_transformation("log(Sepal.Length)"), "log")
 })
 
 test_that("find_transformation - log+x", {
@@ -16,6 +17,7 @@ test_that("find_transformation - log+x", {
 test_that("find_transformation - log+x 2", {
   model <- lm(log(2 + Sepal.Length) ~ Species, data = iris)
   expect_identical(find_transformation(model), "log(x+2)")
+  expect_identical(find_transformation("log(2 + Sepal.Length)"), "log(x+2)")
 })
 
 test_that("find_transformation - log-log", {
@@ -52,6 +54,7 @@ test_that("find_transformation - inverse", {
   data(iris)
   model <- lm(1 / Sepal.Length ~ Species, data = iris)
   expect_identical(find_transformation(model), "inverse")
+  expect_identical(find_transformation("1 / Sepal.Length"), "inverse")
 })
 
 test_that("find_transformation - detect powers", {
@@ -72,6 +75,7 @@ test_that("find_transformation - detect powers", {
   expect_identical(insight::find_transformation(m5), "power")
   expect_identical(insight::find_transformation(m6), "power")
   expect_identical(insight::find_transformation(m7), "power")
+  expect_identical(insight::find_transformation("Sepal.Length^-0.5"), "power")
 
   # power **