Fixed dist_gamma() not allowing the scale parameter to be used

Resolves #132
mitchelloharawild · Jan 4, 2025 · 9d88185 · 9d88185
1 parent 683b96e
commit 9d88185
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diff --git a/NEWS.md b/NEWS.md
@@ -5,6 +5,10 @@
 * Transformed distributions now work better for monotonic increasing functions 
   when the domain of the untransformed distribution is R (#129).
 
+## Bug fixes
+
+* Fixed `dist_gamma()` not allowing the `scale` parameter to be used (#132).
+
 ## Breaking changes
 
 * The `quantile()` method for `dist_multivariate_normal()` now defaults to 

diff --git a/R/dist_gamma.R b/R/dist_gamma.R
@@ -80,8 +80,11 @@
 #'
 #' @name dist_gamma
 #' @export
-dist_gamma <- function(shape, rate, scale = 1/rate){
+dist_gamma <- function(shape, rate = 1/scale, scale = 1/rate){
   shape <- vec_cast(shape, double())
+  if(missing(rate) && missing(scale)) {
+    abort("Either the `rate` or `scale` must be specified for Gamma distributions.")
+  }
   rate <- vec_cast(rate, double())
   if(any(shape[!is.na(shape)] < 0)){
     abort("The shape parameter of a Gamma distribution must be non-negative.")