Alex's .py

Hi, I'm Alex. I created this Python blog to show people the latest games and code I'm working on, along with explanations and examples for anyone looking to learn more about Python, CGI / server-side programming, or just internet game development in general. Let me know what you think, and thanks for visiting!

Jan 14, 2012 : one_card_poker.py

Here's a breakdown of how the one_card_poker.py source code works, in 5 easy steps...

In its simplest form, playing a hand of poker consists of 4 basic phases: dealing, betting, comparing and paying out. Note that phases 1, 3 & 4 can occur automatically, but phase 2 (betting) requires the player to make a decision.

Therefore, the computer program can only carry the game up to the point where we ask player 1 what his bet is before it has to pause and wait for an answer. As we know from our other games, pausing inside of an actively running python program is not practical in a static html CGI environment. Instead, we choose to end the python program, print a display to the html screen asking the user for his bet and utilize branched recursion to finish phases 3 & 4 after the information we need to continue has been entered. This results in two different kind of displays, which we call frames, that could be printed to the game's (html) GUI: a dealing frame & an evaluation frame. As you'll see in the code below, distinguishing between the two is critical for the program to run successfully.

Check if the program is being asked to excecute a dealing frame or an evaluation frame...

#!/usr/bin/python import cgi, cgitb, re cgitb.enable() form = cgi.FieldStorage() ante = float(form.getvalue('ante')) eval_frame = int(form.getvalue('eval_frame')) deck = ['2','3','4','5','6','7','8','9','10','J','Q','K','A'] if ante == 1 and eval_frame == 0: # then, initialize vars... player_first = 1 player_chips = 20. current_pot = 0 dealer_chips = 20. else: player_first = int(form.getvalue('player_first')) player_chips = float(form.getvalue('player_chips')) current_pot = float(form.getvalue('current_pot')) dealer_chips = float(form.getvalue('dealer_chips'))

Define a few decision-making functions (AI) for the dealer based on the strength of the cards he can see and some other game variables...

def dealer_bet(player_val,player_chips): if player_val <= 4: bet = .65player_chips elif player_val <= 8: bet = .10player_chips else: bet = 0 return bet def dealer_fold_or_call(player_val,player_chips,bet): if bet < .56 or player_val <= 4: call = 1 elif player_val <= 8 and bet < .18player_chips: call = 1 else: call = 0 return call

Define a function that checks to make sure both player's bets are real, possible bets that make sense...

def check_bet(bet,player_chips,comp_chips): if bet < 0: bet = 0. max_bet = min(player_chips,comp_chips) if bet > max_bet: bet = max_bet bet = round(bet,2) return bet

If this is a dealing frame, then execute the dealing branch of the program and print the dealing screen to the html display...

if eval_frame != 1: # then, start dealing hand... player_chips -= ante dealer_chips -= ante current_pot = 2ante import random dealer_val = random.randint(0,len(deck)-1) dealer_card = deck[dealer_val] player_val = random.randint(0,len(deck)-1) player_card = deck[player_val] if player_first == 1: comments = "Player bets first. Enter your bet: " eval_frame = 1 print "Content-type:text/html\r\n\r\n" print '<html><body>' print '<h2 style="font-family:courier; font-size:20px; text-align:left;">' print '<table border="1" style="font-family:courier; font-size:16px; text-align:center;">' print "<td width=150>Player's Chips</td>" print "<td width=150>Player's Card</td>" print '<td width=150>In the Pot:</td>' print "<td width=150>Dealer's Card</td>" print "<td width=150>Dealer's Chips</td>" print '<tr>' print '<td width=150>' + str(player_chips) + '</td>' print '<td width=150><p style="color:red;">' + '?' + '</p></td>' print '<td width=150>' + str(current_pot) + '</td>' print '<td width=150><p style="color:red;">' + deck[dealer_val] + '</p></td>' print '<td width=150>' + str(dealer_chips) + '</td>' print '</table>' print '<table style="font-family:courier; font-size:16px; text-align:left;">' print '<td>' print '<form action="http://alexspy.com/cgi-bin/high_card_monte_bluehost.py" method="post">' print comments print '<input type="text" name="bet" size="5" maxlength="5">' print '<input type="hidden" name="ante" value="' + str(ante) + '" />' print '<input type="hidden" name="eval_frame" value="' + str(eval_frame) + '" />' print '<input type="hidden" name="player_first" value="' + str(player_first) + '" />' print '<input type="hidden" name="player_chips" value="' + str(player_chips) + '" />' print '<input type="hidden" name="player_val" value="' + str(player_val) + '" />' print '<input type="hidden" name="current_pot" value="' + str(current_pot) + '" />' print '<input type="hidden" name="dealer_chips" value="' + str(dealer_chips) + '" />' print '<input type="hidden" name="dealer_val" value="' + str(dealer_val) + '" />' print '<input type="submit" value="Enter" />' print '</form>' print '</td>' print '</table>' print '</h2></body></html>' else: bet = dealer_bet(player_val,player_chips) bet = check_bet(bet,player_chips,dealer_chips) dealer_chips -= bet current_pot += bet comments = 'Dealer bets ' + str(bet) + ' chips. Do you call or fold?' eval_frame = 1 print "Content-type:text/html\r\n\r\n" print '<html><body>' print '<h2 style="font-family:courier; font-size:20px; text-align:left;">' print '<table border="1" style="font-family:courier; font-size:16px; text-align:center;">' print "<td width=150>Player's Chips</td>" print "<td width=150>Player's Card</td>" print '<td width=150>In the Pot:</td>' print "<td width=150>Dealer's Card</td>" print "<td width=150>Dealer's Chips</td>" print '<tr>' print '<td width=150>' + str(player_chips) + '</td>' print '<td width=150><p style="color:red;">' + '?' + '</p></td>' print '<td width=150>' + str(current_pot) + '</td>' print '<td width=150><p style="color:red;">' + deck[dealer_val] + '</p></td>' print '<td width=150>' + str(dealer_chips) + '</td>' print '</table>' print '<table style="font-family:courier; font-size:16px; text-align:left;">' print '<td>' print '<form action="http://alexspy.com/cgi-bin/high_card_monte_bluehost.py" method="post">' print comments print '<select name="player_call">' print '<option value="1" selected>Call</option><option value="-1">Fold</option></select>' print '<input type="hidden" name="ante" value="' + str(ante) + '" />' print '<input type="hidden" name="eval_frame" value="' + str(eval_frame) + '" />' print '<input type="hidden" name="player_first" value="' + str(player_first) + '" />' print '<input type="hidden" name="player_chips" value="' + str(player_chips) + '" />' print '<input type="hidden" name="player_val" value="' + str(player_val) + '" />' print '<input type="hidden" name="current_pot" value="' + str(current_pot) + '" />' print '<input type="hidden" name="dealer_chips" value="' + str(dealer_chips) + '" />' print '<input type="hidden" name="dealer_val" value="' + str(dealer_val) + '" />' print '<input type="hidden" name="bet" value="' + str(bet) + '" />' print '<input type="submit" value="Enter" />' print '</form>' print '</td>' print '</table>' print '</h2></body></html>'

If this is an evaluation frame, then execute the eval branch of the program and print the eval screen to the html display...

else: # eval frame... bet = float(form.getvalue('bet')) bet = check_bet(bet,player_chips,dealer_chips) player_val = int(form.getvalue('player_val')) dealer_val = int(form.getvalue('dealer_val')) if player_first == 1: player_chips -= bet current_pot += bet player_call = 1 dealer_call = dealer_fold_or_call(player_val,player_chips,bet) if dealer_call == 1: dealer_chips -= bet current_pot += bet else: # dealer was first... dealer_call = 1 player_call = int(form.getvalue('player_call')) if player_call == 1: player_chips -= bet current_pot += bet if dealer_call <= 0 and player_val > dealer_val: player_chips += current_pot comments = "Dealer folds. You win the pot!" elif dealer_call <= 0 and player_val <= dealer_val: player_chips += current_pot comments = "Congratulations, you bluffed the Dealer!" elif player_call <= 0 and player_val < dealer_val: dealer_chips += current_pot comments = "You fold. Dealer wins the pot!" elif player_call <= 0 and player_val >= dealer_val: dealer_chips += current_pot comments = "Haha! Alex's computer code bluffed you!" elif player_val > dealer_val: player_chips += current_pot comments = "Both players call. You win the pot!" elif player_val < dealer_val: dealer_chips += current_pot comments = "Both players call. Dealer wins the pot!" else: player_chips += current_pot/2 dealer_chips += current_pot/2 comments = "Tie! Players split the pot." current_pot = 0 player_first = -1 eval_frame = 0 if player_chips < .01 or dealer_chips < .01: if player_chips > dealer_chips: comments = "Congratulations!! You won the game!" else: comments = "You lost the game! Alex's code out-smarted you!!" ante = 1 else: ramp_rate = 1.15 if ante < 5: ante = round(anteramp_rate,2); if ante > 5: ante = 5.; if ante > min(player_chips,dealer_chips): ante = min(player_chips,dealer_chips) # then print html displaying result... print "Content-type:text/html\r\n\r\n" print '<html><body>' print '<h2 style="font-family:courier; font-size:20px; text-align:left;">' print '<table border="1" style="font-family:courier; font-size:16px; text-align:center;">' print "<td width=150>Player's Chips</td>" print "<td width=150>Player's Card</td>" print '<td width=150>In the Pot:</td>' print "<td width=150>Dealer's Card</td>" print "<td width=150>Dealer's Chips</td>" print '<tr>' print '<td width=150>' + str(player_chips) + '</td>' print '<td width=150><p style="color:red;">' + deck[player_val] + '</p></td>' print '<td width=150>' + str(current_pot) + '</td>' print '<td width=150><p style="color:red;">' + deck[dealer_val] + '</p></td>' print '<td width=150>' + str(dealer_chips) + '</td>' print '</table>' print '<table style="font-family:courier; font-size:16px; text-align:left;">' print '<td>' print '<form action="http://alexspy.com/cgi-bin/high_card_monte_bluehost.py" method="post">' print comments print '<input type="hidden" name="ante" value="' + str(ante) + '" />' print '<input type="hidden" name="eval_frame" value="' + str(eval_frame) + '" />' print '<input type="hidden" name="player_first" value="' + str(player_first) + '" />' print '<input type="hidden" name="player_chips" value="' + str(player_chips) + '" />' print '<input type="hidden" name="current_pot" value="' + str(current_pot) + '" />' print '<input type="hidden" name="dealer_chips" value="' + str(dealer_chips) + '" />' print '<input type="submit" value="Continue" />' print '</form>' print '</td>' print '</table>' print '</h2></body></html>'

Here's some other great python blogs I like to check out:

Nadia Alramli's Blog
The "Invent with Python" Blog
Carter Sande's Blog