How to make Chess game in Python
Explained in hindi .
The source of code 👇
"""CONVENTIONS:
positions are done row-column from the bottom left and are both numbers. This corresponds to the alpha-number system in traditional chess while being computationally useful. they are specified as tuples
"""
import itertools
WHITE = "white"
BLACK = "black"
class Game:
#ive decided since the number of pieces is capped but the type of pieces is not (pawn transformations), I've already coded much of the modularity to support just using a dictionary of pieces
def __init__(self):
self.playersturn = BLACK
self.message = "this is where prompts will go"
self.gameboard = {}
self.placePieces()
print("chess program. enter moves in algebraic notation separated by space")
self.main()
def placePieces(self):
for i in range(0,8):
self.gameboard[(i,1)] = Pawn(WHITE,uniDict[WHITE][Pawn],1)
self.gameboard[(i,6)] = Pawn(BLACK,uniDict[BLACK][Pawn],-1)
placers = [Rook,Knight,Bishop,Queen,King,Bishop,Knight,Rook]
for i in range(0,8):
self.gameboard[(i,0)] = placers[i](WHITE,uniDict[WHITE][placers[i]])
self.gameboard[((7-i),7)] = placers[i](BLACK,uniDict[BLACK][placers[i]])
placers.reverse()
def main(self):
while True:
self.printBoard()
print(self.message)
self.message = ""
startpos,endpos = self.parseInput()
try:
target = self.gameboard[startpos]
except:
self.message = "could not find piece; index probably out of range"
target = None
if target:
print("found "+str(target))
if target.Color != self.playersturn:
self.message = "you aren't allowed to move that piece this turn"
continue
if target.isValid(startpos,endpos,target.Color,self.gameboard):
self.message = "that is a valid move"
self.gameboard[endpos] = self.gameboard[startpos]
del self.gameboard[startpos]
self.isCheck()
if self.playersturn == BLACK:
self.playersturn = WHITE
else : self.playersturn = BLACK
else :
self.message = "invalid move" + str(target.availableMoves(startpos[0],startpos[1],self.gameboard))
print(target.availableMoves(startpos[0],startpos[1],self.gameboard))
else : self.message = "there is no piece in that space"
def isCheck(self):
#ascertain where the kings are, check all pieces of opposing color against those kings, then if either get hit, check if its checkmate
king = King
kingDict = {}
pieceDict = {BLACK : [], WHITE : []}
for position,piece in self.gameboard.items():
if type(piece) == King:
kingDict[piece.Color] = position
print(piece)
pieceDict[piece.Color].append((piece,position))
#white
if self.canSeeKing(kingDict[WHITE],pieceDict[BLACK]):
self.message = "White player is in check"
if self.canSeeKing(kingDict[BLACK],pieceDict[WHITE]):
self.message = "Black player is in check"
def canSeeKing(self,kingpos,piecelist):
#checks if any pieces in piece list (which is an array of (piece,position) tuples) can see the king in kingpos
for piece,position in piecelist:
if piece.isValid(position,kingpos,piece.Color,self.gameboard):
return True
def parseInput(self):
try:
a,b = input().split()
a = ((ord(a[0])-97), int(a[1])-1)
b = (ord(b[0])-97, int(b[1])-1)
print(a,b)
return (a,b)
except:
print("error decoding input. please try again")
return((-1,-1),(-1,-1))
"""def validateInput(self, *kargs):
for arg in kargs:
if type(arg[0]) is not type(1) or type(arg[1]) is not type(1):
return False
return True"""
def printBoard(self):
print(" 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |")
for i in range(0,8):
print("-"*32)
print(chr(i+97),end="|")
for j in range(0,8):
item = self.gameboard.get((i,j)," ")
print(str(item)+' |', end = " ")
print()
print("-"*32)
"""game class. contains the following members and methods:
two arrays of pieces for each player
8x8 piece array with references to these pieces
a parse function, which turns the input from the user into a list of two tuples denoting start and end points
a checkmateExists function which checks if either players are in checkmate
a checkExists function which checks if either players are in check (woah, I just got that nonsequitur)
a main loop, which takes input, runs it through the parser, asks the piece if the move is valid, and moves the piece if it is. if the move conflicts with another piece, that piece is removed. ischeck(mate) is run, and if there is a checkmate, the game prints a message as to who wins
"""
class Piece:
def __init__(self,color,name):
self.name = name
self.position = None
self.Color = color
def isValid(self,startpos,endpos,Color,gameboard):
if endpos in self.availableMoves(startpos[0],startpos[1],gameboard, Color = Color):
return True
return False
def __repr__(self):
return self.name
def __str__(self):
return self.name
def availableMoves(self,x,y,gameboard):
print("ERROR: no movement for base class")
def AdNauseum(self,x,y,gameboard, Color, intervals):
"""repeats the given interval until another piece is run into.
if that piece is not of the same color, that square is added and
then the list is returned"""
answers = []
for xint,yint in intervals:
xtemp,ytemp = x+xint,y+yint
while self.isInBounds(xtemp,ytemp):
#print(str((xtemp,ytemp))+"is in bounds")
target = gameboard.get((xtemp,ytemp),None)
if target is None: answers.append((xtemp,ytemp))
elif target.Color != Color:
answers.append((xtemp,ytemp))
break
else:
break
xtemp,ytemp = xtemp + xint,ytemp + yint
return answers
def isInBounds(self,x,y):
"checks if a position is on the board"
if x >= 0 and x < 8 and y >= 0 and y < 8:
return True
return False
def noConflict(self,gameboard,initialColor,x,y):
"checks if a single position poses no conflict to the rules of chess"
if self.isInBounds(x,y) and (((x,y) not in gameboard) or gameboard[(x,y)].Color != initialColor) : return True
return False
chessCardinals = [(1,0),(0,1),(-1,0),(0,-1)]
chessDiagonals = [(1,1),(-1,1),(1,-1),(-1,-1)]
def knightList(x,y,int1,int2):
"""sepcifically for the rook, permutes the values needed around a position for noConflict tests"""
return [(x+int1,y+int2),(x-int1,y+int2),(x+int1,y-int2),(x-int1,y-int2),(x+int2,y+int1),(x-int2,y+int1),(x+int2,y-int1),(x-int2,y-int1)]
def kingList(x,y):
return [(x+1,y),(x+1,y+1),(x+1,y-1),(x,y+1),(x,y-1),(x-1,y),(x-1,y+1),(x-1,y-1)]
class Knight(Piece):
def availableMoves(self,x,y,gameboard, Color = None):
if Color is None : Color = self.Color
return [(xx,yy) for xx,yy in knightList(x,y,2,1) if self.noConflict(gameboard, Color, xx, yy)]
class Rook(Piece):
def availableMoves(self,x,y,gameboard ,Color = None):
if Color is None : Color = self.Color
return self.AdNauseum(x, y, gameboard, Color, chessCardinals)
class Bishop(Piece):
def availableMoves(self,x,y,gameboard, Color = None):
if Color is None : Color = self.Color
return self.AdNauseum(x, y, gameboard, Color, chessDiagonals)
class Queen(Piece):
def availableMoves(self,x,y,gameboard, Color = None):
if Color is None : Color = self.Color
return self.AdNauseum(x, y, gameboard, Color, chessCardinals+chessDiagonals)
class King(Piece):
def availableMoves(self,x,y,gameboard, Color = None):
if Color is None : Color = self.Color
return [(xx,yy) for xx,yy in kingList(x,y) if self.noConflict(gameboard, Color, xx, yy)]
class Pawn(Piece):
def __init__(self,color,name,direction):
self.name = name
self.Color = color
#of course, the smallest piece is the hardest to code. direction should be either 1 or -1, should be -1 if the pawn is traveling "backwards"
self.direction = direction
def availableMoves(self,x,y,gameboard, Color = None):
if Color is None : Color = self.Color
answers = []
if (x+1,y+self.direction) in gameboard and self.noConflict(gameboard, Color, x+1, y+self.direction) : answers.append((x+1,y+self.direction))
if (x-1,y+self.direction) in gameboard and self.noConflict(gameboard, Color, x-1, y+self.direction) : answers.append((x-1,y+self.direction))
if (x,y+self.direction) not in gameboard and Color == self.Color : answers.append((x,y+self.direction))# the condition after the and is to make sure the non-capturing movement (the only fucking one in the game) is not used in the calculation of checkmate
return answers
uniDict = {WHITE : {Pawn : "♙", Rook : "♖", Knight : "♘", Bishop : "♗", King : "♔", Queen : "♕" }, BLACK : {Pawn : "♟", Rook : "♜", Knight : "♞", Bishop : "♝", King : "♚", Queen : "♛" }}
Game()
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