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# Chess
```elixir
Mix.install([
{:chess_logic, "~> 0.3.0"},
{:flow, "~> 1.2.4"}])
```
## Section
```elixir
base_dir = "/Users/guy/Projects/book/data/lichess/Lichess Elite Database/"
```
```elixir
ChessLogic.from_pgn(
"""
[Event "Rated Blitz game"]
[Date "????.??.??"]
[Round "?"]
[White "pacal56"]
[Black "LegendaryTeam"]
[Result "0-1"]
[WhiteElo "2210"]
[BlackElo "2464"]
[ECO "B62"]
[Opening "Sicilian Defense: Richter-Rauzer, 6...e6"]
[TimeControl "180+0"]
[UTCDate "2015.01.05"]
[UTCTime "20:42:50"]
[Termination "Normal"]
[WhiteRatingDiff "-4"]
[BlackRatingDiff "+8"]
1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 Nc6 6. Bg5 e6 7. f4 h6 8.
Bh4 Be7 9. Nf3 Nxe4 10. Nxe4 Bxh4+ 11. Nxh4 Qxh4+ 12. g3 Qd8 13. Nxd6+ Ke7
14. Ne4 Qxd1+ 15. Rxd1 Bd7 16. Nc5 Be8 17. Bg2 b6 18. Nd3 Rc8 19. c3 Bd7
20. O-O Rhd8 21. Rfe1 Kf8 22. Kf2 Be8 23. Bxc6 Bxc6 24. Ke3 Ba4 25. b3 Be8
26. c4 f6 27. Nb4 Ke7 28. g4 Kf7 29. h3 g5 30. Nd3 Ke7 31. fxg5 hxg5 32.
Nf2 Bg6 33. Ne4 Bxe4 34. Kxe4 Rxd1 35. Rxd1 Rd8 36. Rxd8 Kxd8 37. b4 Kd7
38. a3 Kd6 39. Kd4 Kd7 40. Ke4 Ke7 41. Kd4 Kd7 42. Ke4 Kd6 43. Kd4 f5 44.
gxf5 exf5 45. a4 a5 46. c5+ bxc5+ 47. bxc5+ Kc6 48. Ke5 f4 49. Ke4 Kxc5 50.
h4 gxh4 51. Kxf4 Kb4 52. Kg4 Kxa4 53. Kxh4 Kb3 0-1
"""
) |> then(fn [game]-> game end) # Enum.at(game.history, -9).fen end)
```
```elixir
defmodule LoadPGN do
def chunk(contents) do
contents
|> Stream.chunk_while(
[],
fn elem, acc ->
if String.starts_with?(elem, "[Event") do
{:cont, acc |> Enum.reverse() |> Enum.join(), [elem]}
else
{:cont, [elem | acc]}
end
end,
fn
[] -> {:cont, []}
acc -> {:cont, Enum.reverse(acc) |> Enum.join(), []}
end)
|> Stream.filter(&String.starts_with?(&1, "[Event"))
end
def load(pgn) do
ChessLogic.from_pgn(pgn)
rescue e ->
IO.puts "barfed on: #{pgn}"
IO.puts inspect(e)
end
def split(filename) do
if String.ends_with?(filename, ".pgn") do
base_name = String.trim_trailing(filename, ".pgn")
File.open(filename, [:read, :utf], fn file ->
file
|> IO.stream(:line)
|> chunk()
|> Stream.with_index()
|> Stream.each(
fn {pgn, i} ->
g = ChessLogic.from_pgn(pgn) |> hd()
# if length(g.history) >= 9 do
# fen = Enum.at(g.history, -9).fen
# #IO.puts(pgn)
# IO.puts("#{i}: \"#{fen}\"")
# else
IO.puts("#{i}: -")
# end
end
)
|> Stream.run()
end)
else
{:error, "not a .pgn"}
end
end
end
LoadPGN.split("#{base_dir}/lichess_elite_2015-01.pgn")
```
```elixir
# Path.wildcard("#{base_dir}/*2014-05.pgn")
# |> Enum.each(
# fn file ->
# IO.puts("file: #{file}")
# {:ok, contents} = File.read(file)
# contents
# |> LoadPGN.split()
# |> Enum.reject(& &1 == "")
# |> IO.inspect()
# |> Enum.map(&LoadPGN.load/1)
# |> Enum.with_index()
# |> Enum.each(fn {g, _i} ->
# IO.inspect(g)
# # IO.puts("game: #{i}")
# # Enum.at(g.history, 0).fen
# # |> ChessLogic.Position.from_fen()
# # |> ChessLogic.Position.print()
# end)
# end
# )
```
```elixir
# g = ChessLogic.from_pgn_file("lichess_elite_2013-09.pgn")
# length(g)
Path.wildcard("#{base_dir}/*2015-01.pgn")
|> Flow.from_enumerable()
|> Flow.flat_map(
fn file ->
file
|> ChessLogic.from_pgn_file()
|> Enum.map(fn g -> Enum.at(g.history, -21).fen end)
end
)
|> Flow.partition()
|> Flow.reduce(
fn -> %{} end,
fn fen, map -> Map.update(map, fen, 1, & &1 + 1) end)
|> Flow.take_sort(10, fn {_pos_a, count_a}, {_pos_b, count_b} -> count_b <= count_a end)
|> Enum.to_list()
|> hd()
|> Enum.each(
fn {fen, count} ->
ChessLogic.Position.from_fen(fen) |> ChessLogic.Position.print()
IO.puts "occurred #{count} times"
end)
```
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