Merge pull request #169 from ffreyer/ff/adapted_grid

Use StableRNGs for `adapted_grid()`

Project.toml

@@ -6,20 +6,22 @@ version = "1.4.1"
 ColorSchemes = "35d6a980-a343-548e-a6ea-1d62b119f2f4"
 Colors = "5ae59095-9a9b-59fe-a467-6f913c188581"
 Dates = "ade2ca70-3891-5945-98fb-dc099432e06a"
+PrecompileTools = "aea7be01-6a6a-4083-8856-8a6e6704d82a"
 Printf = "de0858da-6303-5e67-8744-51eddeeeb8d7"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 Reexport = "189a3867-3050-52da-a836-e630ba90ab69"
-PrecompileTools = "aea7be01-6a6a-4083-8856-8a6e6704d82a"
+StableRNGs = "860ef19b-820b-49d6-a774-d7a799459cd3"
 Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 
 [compat]
 ColorSchemes = "3.19 - 4"
 Colors = "0.12"
 Dates = "<0.0.1, 1"
+PrecompileTools = "1"
 Printf = "<0.0.1, 1"
 Random = "<0.0.1, 1"
 Reexport = "1"
-PrecompileTools = "1"
+StableRNGs = "1"
 Statistics = "<0.0.1, 1"
 julia = "1.6"
 

src/PlotUtils.jl

@@ -8,7 +8,7 @@ using Dates
 
 @reexport using Colors
 import Base: getindex
-import Random: MersenneTwister
+import StableRNGs: StableRNG
 
 export ColorGradient,
     ColorPalette,

src/adapted_grid.jl

@@ -16,7 +16,7 @@ function adapted_grid(
     minmax::Tuple{Number,Number};
     max_recursions = 7,
     max_curvature = 0.01,
-    n_points = 31,
+    n_points = 31
 )
     if minmax[1] > minmax[2]
         throw(ArgumentError("interval must be given as (min, max)"))
@@ -34,7 +34,7 @@ function adapted_grid(
     xs[end - 1] = xs[end] - (xs[end] - xs[end - 1]) / 4
 
     # Wiggle interior points a bit to prevent aliasing and other degenerate cases
-    rng = MersenneTwister(1337)
+    rng = StableRNG(1337)
     rand_factor = 0.05
     for i ∈ 2:(length(xs) - 1)
         xs[i] += 2rand_factor * (rand(rng) - 0.5) * (xs[i + 1] - xs[i - 1])

test/runtests.jl

@@ -271,9 +271,15 @@ end
         @test fs |> extrema |> collect |> diff |> first > 1.9
     end
 
-    let f = sinc, int = (0, 40)  # JuliaPlots/Plots.jl/issues/3894
-        xs, fs = adapted_grid(f, int)
-        @test length(xs) > 400
+    let f = sinc, int = (-40, 40)  # JuliaPlots/Plots.jl/issues/3894
+        xs, fs = adapted_grid(sinc, int)
+        roots = vcat(int[1]:-1, 1:int[2])
+        count_per_extrema = map(1:length(roots)-1) do idx
+            left = roots[idx]; right = roots[idx+1]
+            return count(x -> left < x < right, xs)
+        end
+        # check that we have at least 5 points for each extrema
+        @test all(count_per_extrema .>= 5)
     end
 end