RosettaCodeData/Task/Galton-box-animation/Mathematica/galton-box-animation.math
2023-07-01 13:44:08 -04:00

54 lines
1.7 KiB
Text

ClearAll[MakePathFunction]
MakePathFunction[{path_, acumpath_}] :=
Module[{f1, f2, f3, pf, n = Length[path]},
f1 = MapThread[{#1/2, #2 + 0.5 < z <= #2 + 1} &, {acumpath,
n - Range[n + 1]}];
f2 = MapThread[{#1/2 + #2 Sqrt[1/4 - (z - #3)^2], #3 <
z <= #3 + 1/2} &, {acumpath // Most, path, n - Range[n]}];
f3 = {{acumpath[[-1]]/2, z <= 0}};
pf = Piecewise[Evaluate[Join[f1, f2, f3]], 0];
pf
]
MakeScene[pfs_List, zfinals_List, n_Integer, t_] :=
Module[{durations, accumduration, if, part, fixed, relt},
durations = n - zfinals;
accumduration = Accumulate[Prepend[durations, 0]];
if = Interpolation[{accumduration, Range[Length[zfinals] + 1]} //
Transpose, InterpolationOrder -> 1];
part = Floor[if[t]];
If[part > 0,
fixed = Table[{pfs[[i]], z} /. z -> zfinals[[i]], {i, part - 1}];
,
fixed = {};
];
relt = t - accumduration[[part]];
relt = n - relt;
Append[fixed, {pfs[[part]] /. z -> relt, relt}]
]
SeedRandom[1234];
n = 6;
m = 150;
r = 0.25; (* fixed *)
dots =
Catenate@Table[{# - i/2 - 1/2, n - i} & /@ Range[i], {i, n}];
g = Graphics[Disk[#, r] & /@ dots, Axes -> True];
paths = RandomChoice[{-1, 1}, {m, n}];
paths = {#, Accumulate[Prepend[#, 0]]} & /@ paths;
xfinals = paths[[All, 2, -1]];
types = DeleteDuplicates[xfinals];
zfinals = ConstantArray[0, Length[paths]];
Do[
pos = Flatten[Position[xfinals, t]];
zfinals[[pos]] += 0.5 Range[Length[pos]];
,
{t, types}
];
max = Max[zfinals] + 1;
zfinals -= max;
pfs = MakePathFunction /@ paths;
Manipulate[
Graphics[{Disk[#, r] & /@ dots, Red,
Disk[#, r] & /@ MakeScene[pfs, zfinals, n, t]},
PlotRange -> {{-n, n}, {Min[zfinals] - 1, n + 2}},
ImageSize -> 150], {t, 0, Total[n - zfinals] - 0.001}]