refactor StopAfterNoImprovement

src/core/stop_conditions.jl

@@ -105,17 +105,6 @@ function (s::StopAfterEpisode)(agent, env)
     s.cur >= s.episode
 end
 
-#####
-# StopAfterNoImprovement
-#####
-
-mutable struct StopAfterNoImprovement{F,B<:CircularArrayBuffer,T<:Number}
-    fn::F
-    buffer::B
-    δ::T
-    peak::T
-end
-
 """
 StopAfterNoImprovement()
 
@@ -134,16 +123,34 @@ patience: Number of epochs with no improvement after which training will be stop
 
 Return `true` after the monitored metric has stopped improving.
 """
-function StopAfterNoImprovement(fn, patience::Int, δ::T = 0.0f0) where {T<:Number}
-    StopAfterNoImprovement(fn, CircularArrayBuffer{T}(1, patience), δ, T(0))
+mutable struct StopAfterNoImprovement{T<:Number,F}
+    fn::F
+    patience::Int
+    δ::T
+    peak::T
+    counter::Int
+end
+
+function StopAfterNoImprovement(
+    fn,
+    patience::Int,
+    δ::T = 0.0f0,
+) where {T<:Number}
+    StopAfterNoImprovement(fn, patience, δ, typemin(T), 1)
 end
 
 function (s::StopAfterNoImprovement)(agent, env)::Bool
     is_terminated(env) || return false # post episode stage
     val = s.fn()
-    s.peak = max(val, s.peak)
-    push!(s.buffer, val)
-    isfull(s.buffer) ? all(s.buffer .< (s.peak - s.δ)) : false
+    if val > s.peak - s.δ
+        s.counter = 1
+        s.peak = max(val, s.peak)
+        return false
+    else
+        s.counter += 1
+        return s.counter > s.patience
+    end
+    return false
 end
 
 #####