Problem with an iterator

[grimm1111]

Hello,

I am trying to write a chess program that grabs a random chess position, sends the position to an evaluation engine, and returns both the position and the evaluation.

I am using three libraries: random, which generates random numbers, stockfish, which is a Python API wrapper for the chess engine "stockfish," and chess, which displays a board and parses the human-readable "pgn" file format and translates it to the "fen" format readable by stockfish.

The issue I believe I am running in to is in the generator in the "move_picker" function below. I have tested the "game_picker" function on its own, and it works properly in isolation.

import chess.pgn
import random
import stockfish
from stockfish import Stockfish

stockfish = Stockfish("/Users/User/stockfish_20011801_x64.exe")


pgn = open("Capablanca.pgn")



def game_picker():
    i = 1
    game_val = random.randint(2,550)
    the_game = chess.pgn.read_game(pgn)
    for i in range(game_val):
        the_game = chess.pgn.read_game(pgn)
    return the_game

        
def move_picker():
    Move_val = random.randint(10,40)
    board3 = the_game.board()
    moves_list = iter(the_game.mainline_moves())
    i = 1
    for i in range(Move_val):
       board3.push(next(moves_list))
    fen_position = board3.fen()
    yield fen_position

    
def run_the_game():
    game_picker()
    move_picker()
    fen_position = move_picker()
    stockfish.set_fen_position(fen_position)
    eval = stockfish.get_evaluation()
    eval = eval["value"]
    print("Stockfish says...  " + str(eval))
    display(board3)
    


run_the_game()

When I run this code, it just hangs, and I get a Windows crash report.

The documentation for the chess library is not good. This is all the relevant information they give:

>>> import chess.pgn
>>>
>>> pgn = open("data/pgn/kasparov-deep-blue-1997.pgn")
>>>
>>> first_game = chess.pgn.read_game(pgn)
>>> second_game = chess.pgn.read_game(pgn)
>>>
>>> first_game.headers["Event"]
'IBM Man-Machine, New York USA'
>>>
>>> # Iterate through all moves and play them on a board.
>>> board = first_game.board()
>>> for move in first_game.mainline_moves():
...     board.push(move)

But I don't want to iterate through ALL moves, just through a random number of moves. So when I try it like this, mirroring the code from the documentation as much as possible, I also get an error.

import chess
import chess.pgn
import random
import stockfish
from stockfish import Stockfish

stockfish = Stockfish("/Users/User/stockfish_20011801_x64.exe")


pgn = open("Capablanca.pgn")



def game_picker():
    i = 1
    game_val = random.randint(2,550)
    the_game = chess.pgn.read_game(pgn)
    for i in range(game_val):
        the_game = chess.pgn.read_game(pgn)
    return the_game

        
def move_picker():
    Move_val = random.randint(10,40)
    board3 = the_game.board()
    for Move_val in the_game.mainline_moves():
        board3.push(move)
    return board3

    
def run_the_game():
    game_picker()
    move_picker()
    fen_position = move_picker()
    fen_position = board3.fen()
    stockfish.set_fen_position(fen_position)
    eval = stockfish.get_evaluation()
    eval = eval["value"]
    print("Stockfish says...  " + str(eval))
    display(board3)
    


run_the_game()

Error:
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-9-8c9bfbf62c3a> in <module>
     51 
     52 
---> 53 run_the_game()
     54 

<ipython-input-9-8c9bfbf62c3a> in run_the_game()
     32     game_picker()
     33     the_game = game_picker()
---> 34     move_picker()
     35     fen_position = move_picker()
     36     fen_position = board3.fen()

<ipython-input-9-8c9bfbf62c3a> in move_picker()
     23 def move_picker():
     24     Move_val = random.randint(10,40)
---> 25     board3 = the_game.board()
     26     for Move_val in the_game.mainline_moves():
     27         board3.push(move)

NameError: name 'the_game' is not defined

I'm at a loss and any help would be greatly appreciated.