microoptimization on rand(::AliasTable) (#1831)

* microoptimization on rand(::AliasTable) * Update src/samplers/aliastable.jl Co-authored-by: David Widmann <devmotion@users.noreply.github.com> --------- Co-authored-by: David Widmann <devmotion@users.noreply.github.com>
JuliaStats · Feb 5, 2024 · 3d71a2b · 3d71a2b
1 parent c1705a3
commit 3d71a2b
Showing 1 changed file with 2 additions and 3 deletions.
diff --git a/src/samplers/aliastable.jl b/src/samplers/aliastable.jl
@@ -15,9 +15,8 @@ end
 
 function rand(rng::AbstractRNG, s::AliasTable)
     i = rand(rng, 1:length(s.alias)) % Int
-    u = rand(rng)
-    @inbounds r = u < s.accept[i] ? i : s.alias[i]
-    r
+    # using `ifelse` improves performance here: github.com/JuliaStats/Distributions.jl/pull/1831/
+    ifelse(rand(rng) < s.accept[i],  i, s.alias[i])
 end
 
 show(io::IO, s::AliasTable) = @printf(io, "AliasTable with %d entries", ncategories(s))