count_functions: Count the moves, half-moves, or positions in a chess game

In dryguy/rbitr: Arbiter: One who ensures adherence to the rules and laws of chess

Count the moves, half-moves, or positions in a chess game

Description

• count_moves() counts the number of moves in the game.

• count_halfmoves() and count_ply() count the number of half-moves in the game.

• count_positions() and count_nodes() count the number of positions in the game.

Usage

count_ply(movetext)

count_nodes(movetext)

count_positions(movetext)

count_moves(movetext)

count_halfmoves(movetext)

Arguments

movetext

A character string containing the movetext of a chess game in either standard algebraic notation (SAN) or UCI-format long algebraic notation (LAN).

Details

In chess, the following terms are used to describe the progression of the game:

Move: A move in chess refers to a sequence in which each player has played one turn. So, one move consists of white playing a "half-move" followed by black playing another "half-move." Thus the number of moves can be an integer or half-integer value. The number of moves is given by the function count_moves(). Repeated moves are included in the count.

Half-Move or Ply: A half-move is a single turn taken by one player. The number of half-moves is given by the function count_halfmoves() or its alias count_ply(). Repeated half-moves are included in the count.

Position or Node: A chess position is the arrangement of the pieces on the board along with the information about castling rights, en passant captures, the side to move, and the 50 move rule. Half-moves are transitions from one position to the next, thus the number of positions is always one more than the number of half-moves. The number of positions in a game is given by the function count_positions() or its alias count_nodes(). The starting position is always included in the count. Repeated positions are also included in the count.

Value

• count_ply() and count_halfmoves() return an integer of the number of half-moves in the game.

• count_nodes() and count_positions() return an integer of the number of positions in the game.

• count_moves() returns the number of moves in the game, which can take on integer or half-integer values.

Examples

count_moves("1. e4 e5 2. Nf3 Nc6")
count_ply("1. e4 e5 2. Nf3 Nc6")
count_halfmoves("1. e4 e5 2. Nf3 Nc6")
count_positions("1. e4 e5 2. Nf3 Nc6")
count_nodes("1. e4 e5 2. Nf3 Nc6")

dryguy/rbitr documentation built on Oct. 15, 2024, 6:18 a.m.