Python 小型项目大全 61~65

六十一、ROT13 密码

原文:http://inventwithpython.com/bigbookpython/project61.html

Python 小型项目大全 61~65_第1张图片

ROT13 密码是最简单的加密算法之一,代表“旋转 13 个空格”密码将字母AZ表示为数字 0 到 25,加密后的字母距离明文字母 13 个空格: A变成NB变成O,以此类推。加密过程和解密过程是一样的,这使得编程变得很简单。然而,加密也很容易被破解。正因为如此,你会经常发现 ROT13 被用来隐藏非敏感信息,如剧透或琐事答案,所以它不会被无意中读取。更多关于 ROT13 密码的信息可以在en.wikipedia.org/wiki/ROT13找到。如果你想更一般地了解密码和密码破解,你可以阅读我的书《Python 密码破解指南》(NoStarch 出版社,2018)。

运行示例

当您运行rot13cipher.py时,输出将如下所示:

ROT13 Cipher, by Al Sweigart email@protected

Enter a message to encrypt/decrypt (or QUIT):
> Meet me by the rose bushes tonight.
The translated message is:
Zrrg zr ol gur ebfr ohfurf gbavtug.

(Copied to clipboard.)
Enter a message to encrypt/decrypt (or QUIT):
`--snip--`

工作原理

ROT13 与项目 6“凯撒密码”共享大量代码,尽管它要简单得多,因为它总是使用密钥 13。因为相同的代码执行加密和解密(第 27 到 39 行),所以没有必要询问玩家他们想要使用哪种模式。

一个不同之处是,这个程序保持原始消息的大小写,而不是自动将消息转换为大写。例如,HELLO加密为URYYB,而Hello加密为Uryyb

"""ROT13 Cipher, by Al Sweigart email@protected
The simplest shift cipher for encrypting and decrypting text.
More info at https://en.wikipedia.org/wiki/ROT13
This code is available at https://nostarch.com/big-book-small-python-programming
Tags: tiny, cryptography"""

try:
   import pyperclip  # pyperclip copies text to the clipboard.
except ImportError:
    pass  # If pyperclip is not installed, do nothing. It's no big deal.

# Set up the constants:
UPPER_LETTERS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
LOWER_LETTERS = 'abcdefghijklmnopqrstuvwxyz'

print('ROT13 Cipher, by Al Sweigart email@protected')
print()

while True:  # Main program loop.
    print('Enter a message to encrypt/decrypt (or QUIT):')
    message = input('> ')

    if message.upper() == 'QUIT':
        break  # Break out of the main program loop.

    # Rotate the letters in message by 13 characters.
    translated = ''
    for character in message:
        if character.isupper():
            # Concatenate uppercase translated character.
            transCharIndex = (UPPER_LETTERS.find(character) + 13) % 26
            translated += UPPER_LETTERS[transCharIndex]
        elif character.islower():
            # Concatenate lowercase translated character.
            transCharIndex = (LOWER_LETTERS.find(character) + 13) % 26
            translated += LOWER_LETTERS[transCharIndex]
        else:
            # Concatenate the character untranslated.
            translated += character

    # Display the translation:
    print('The translated message is:')
    print(translated)
    print()

    try:
        # Copy the translation to the clipboard:
        pyperclip.copy(translated)
        print('(Copied to clipboard.)')
    except:
        pass 

探索程序

试着找出下列问题的答案。尝试对代码进行一些修改,然后重新运行程序,看看这些修改有什么影响。

  1. 如果把第 29 行的character.isupper()改成character.islower()会怎么样?
  2. 如果把第 43 行的print(translated)改成print(message)会怎么样?

六十二、旋转立方体

原文:http://inventwithpython.com/bigbookpython/project62.html

Python 小型项目大全 61~65_第2张图片

这个项目的特点是使用三角函数的 3D 立方体旋转动画。您可以在自己的动画程序中修改 3D 点旋转数学和line()函数。

虽然我们将用来绘制立方体的块文本字符看起来不像细而直的线,但这种绘制被称为线框模型,因为它只渲染物体表面的边缘。图 62-1 显示了立方体和 icosphere 的线框模型,icosphere 是一个由三角形组成的粗糙球体。

Python 小型项目大全 61~65_第3张图片

立方体(左)和 icosphere(右)的线框模型

运行示例

图 62-2 显示了运行rotatingcube.py时的输出。

Python 小型项目大全 61~65_第4张图片

:程序绘制到屏幕上的线框立方体

工作原理

这个算法有两个主要部分:函数line()和函数rotatePoint()。立方体有八个点,每个角一个。程序将这些角存储为CUBE_CORNERS列表中的(x, y, z)元组。这些点也定义了立方体边缘线的连接。当所有的点都向同一个方向旋转相同的量时,它们会产生立方体旋转的错觉。

"""Rotating Cube, by Al Sweigart email@protected
A rotating cube animation. Press Ctrl-C to stop.
This code is available at https://nostarch.com/big-book-small-python-programming
Tags: large, artistic, math"""

# This program MUST be run in a Terminal/Command Prompt window.

import math, time, sys, os

# Set up the constants:
PAUSE_AMOUNT = 0.1  # Pause length of one-tenth of a second.
WIDTH, HEIGHT = 80, 24
SCALEX = (WIDTH - 4) // 8
SCALEY = (HEIGHT - 4) // 8
# Text cells are twice as tall as they are wide, so set scaley:
SCALEY *= 2
TRANSLATEX = (WIDTH - 4) // 2
TRANSLATEY = (HEIGHT - 4) // 2

# (!) Try changing this to '#' or '*' or some other character:
LINE_CHAR = chr(9608)  # Character 9608 is a solid block.

# (!) Try setting two of these values to zero to rotate the cube only
# along a single axis:
X_ROTATE_SPEED = 0.03
Y_ROTATE_SPEED = 0.08
Z_ROTATE_SPEED = 0.13

# This program stores XYZ coordinates in lists, with the X coordinate
# at index 0, Y at 1, and Z at 2\. These constants make our code more
# readable when accessing the coordinates in these lists.
X = 0
Y = 1
Z = 2


def line(x1, y1, x2, y2):
   """Returns a list of points in a line between the given points.

   Uses the Bresenham line algorithm. More info at:
   https://en.wikipedia.org/wiki/Bresenham%27s_line_algorithm"""
   points = []  # Contains the points of the line.
   # "Steep" means the slope of the line is greater than 45 degrees or
   # less than -45 degrees:

   # Check for the special case where the start and end points are
   # certain neighbors, which this function doesn't handle correctly,
   # and return a hard coded list instead:
   if (x1 == x2 and y1 == y2 + 1) or (y1 == y2 and x1 == x2 + 1):
       return [(x1, y1), (x2, y2)]

   isSteep = abs(y2 - y1) > abs(x2 - x1)
   if isSteep:
       # This algorithm only handles non-steep lines, so let's change
       # the slope to non-steep and change it back later.
       x1, y1 = y1, x1  # Swap x1 and y1
       x2, y2 = y2, x2  # Swap x2 and y2
   isReversed = x1 > x2  # True if the line goes right-to-left.

   if isReversed:  # Get the points on the line going right-to-left.
       x1, x2 = x2, x1  # Swap x1 and x2
       y1, y2 = y2, y1  # Swap y1 and y2

       deltax = x2 - x1
       deltay = abs(y2 - y1)
       extray = int(deltax / 2)
       currenty = y2
       if y1 < y2:
           ydirection = 1
       else:
           ydirection = -1
       # Calculate the y for every x in this line:
       for currentx in range(x2, x1 - 1, -1):
           if isSteep:
               points.append((currenty, currentx))
           else:
               points.append((currentx, currenty))
           extray -= deltay
           if extray <= 0:  # Only change y once extray <= 0.
               currenty -= ydirection
               extray += deltax
   else:  # Get the points on the line going left to right.
       deltax = x2 - x1
       deltay = abs(y2 - y1)
       extray = int(deltax / 2)
       currenty = y1
       if y1 < y2:
           ydirection = 1
       else:
           ydirection = -1
       # Calculate the y for every x in this line:
       for currentx in range(x1, x2 + 1):
           if isSteep:
               points.append((currenty, currentx))
           else:
               points.append((currentx, currenty))
           extray -= deltay
           if extray < 0:  # Only change y once extray < 0.
               currenty += ydirection
                extray += deltax
    return points


def rotatePoint(x, y, z, ax, ay, az):
    """Returns an (x, y, z) tuple of the x, y, z arguments rotated.

    The rotation happens around the 0, 0, 0 origin by angles
    ax, ay, az (in radians).
        Directions of each axis:
         -y
          |
          +-- +x
         /
        +z
    """

    # Rotate around x axis:
    rotatedX = x
    rotatedY = (y * math.cos(ax)) - (z * math.sin(ax))
    rotatedZ = (y * math.sin(ax)) + (z * math.cos(ax))
    x, y, z = rotatedX, rotatedY, rotatedZ

    # Rotate around y axis:
    rotatedX = (z * math.sin(ay)) + (x * math.cos(ay))
    rotatedY = y
    rotatedZ = (z * math.cos(ay)) - (x * math.sin(ay))
    x, y, z = rotatedX, rotatedY, rotatedZ

    # Rotate around z axis:
    rotatedX = (x * math.cos(az)) - (y * math.sin(az))
    rotatedY = (x * math.sin(az)) + (y * math.cos(az))
    rotatedZ = z

    return (rotatedX, rotatedY, rotatedZ)


def adjustPoint(point):
    """Adjusts the 3D XYZ point to a 2D XY point fit for displaying on
    the screen. This resizes this 2D point by a scale of SCALEX and
    SCALEY, then moves the point by TRANSLATEX and TRANSLATEY."""
    return (int(point[X] * SCALEX + TRANSLATEX),
            int(point[Y] * SCALEY + TRANSLATEY))


"""CUBE_CORNERS stores the XYZ coordinates of the corners of a cube.
The indexes for each corner in CUBE_CORNERS are marked in this diagram:
      0---1
     /|  /|
    2---3 |
    | 4-|-5
    |/  |/
    6---7"""
CUBE_CORNERS = [[-1, -1, -1], # Point 0
                [ 1, -1, -1], # Point 1
                [-1, -1,  1], # Point 2
                [ 1, -1,  1], # Point 3
                [-1,  1, -1], # Point 4
                [ 1,  1, -1], # Point 5
                [-1,  1,  1], # Point 6
                [ 1,  1,  1]] # Point 7
# rotatedCorners stores the XYZ coordinates from CUBE_CORNERS after
# they've been rotated by rx, ry, and rz amounts:
rotatedCorners = [None, None, None, None, None, None, None, None]
# Rotation amounts for each axis:
xRotation = 0.0
yRotation = 0.0
zRotation = 0.0

try:
    while True:  # Main program loop.
        # Rotate the cube along different axes by different amounts:
        xRotation += X_ROTATE_SPEED
        yRotation += Y_ROTATE_SPEED
        zRotation += Z_ROTATE_SPEED
        for i in range(len(CUBE_CORNERS)):
            x = CUBE_CORNERS[i][X]
            y = CUBE_CORNERS[i][Y]
            z = CUBE_CORNERS[i][Z]
            rotatedCorners[i] = rotatePoint(x, y, z, xRotation,
                yRotation, zRotation)

        # Get the points of the cube lines:
        cubePoints = []
        for fromCornerIndex, toCornerIndex in ((0, 1), (1, 3), (3, 2), (2, 0), (0, 4), (1, 5), (2, 6), (3, 7), (4, 5), (5, 7), (7, 6), (6, 4)):
            fromX, fromY = adjustPoint(rotatedCorners[fromCornerIndex])
            toX, toY = adjustPoint(rotatedCorners[toCornerIndex])
            pointsOnLine = line(fromX, fromY, toX, toY)
            cubePoints.extend(pointsOnLine)

        # Get rid of duplicate points:
        cubePoints = tuple(frozenset(cubePoints))

        # Display the cube on the screen:
        for y in range(HEIGHT):
            for x in range(WIDTH):
                if (x, y) in cubePoints:
                    # Display full block:
                    print(LINE_CHAR, end='', flush=False)
                else:
                    # Display empty space:
                    print(' ', end='', flush=False)
            print(flush=False)
        print('Press Ctrl-C to quit.', end='', flush=True)

        time.sleep(PAUSE_AMOUNT)  # Pause for a bit.

        # Clear the screen:
        if sys.platform == 'win32':
            os.system('cls')  # Windows uses the cls command.
        else:
            os.system('clear')  # macOS and Linux use the clear command.

except KeyboardInterrupt:
    print('Rotating Cube, by Al Sweigart email@protected')
    sys.exit()  # When Ctrl-C is pressed, end the program. 

在输入源代码并运行几次之后,尝试对其进行实验性的修改。标有(!)的注释对你可以做的小改变有建议。你也可以自己想办法做到以下几点:

  • 修改CUBE_CORNERS和第 184 行的元组,创建不同的线框模型,如金字塔和扁平六边形。
  • CUBE_CORNERS的坐标增加1.5,使立方体围绕屏幕中心旋转,而不是围绕自己的中心旋转。

探索程序

试着找出下列问题的答案。尝试对代码进行一些修改,然后重新运行程序,看看这些修改有什么影响。

  1. 如果删除或注释掉第 208 到 211 行会发生什么?
  2. 如果把 184 行的元组改成<((0, 1), (1, 3), (3, 2), (2, 0), (0,4), (4, 5), (5, 1))>会怎么样?

六十三、乌尔皇家游戏

原文:http://inventwithpython.com/bigbookpython/project63.html

Python 小型项目大全 61~65_第5张图片

乌尔的皇家游戏是一个来自美索不达米亚的有 5000 年历史的游戏。考古学家在 1922 年至 1934 年间的挖掘过程中,在现代伊拉克南部的乌尔皇家墓地重新发现了这款游戏。这些规则是根据游戏棋盘(如图 63-1 所示)和一块巴比伦泥板重建的,它们类似于 Parcheesi。你需要运气和技巧才能赢。

Python 小型项目大全 61~65_第6张图片

图 63-1 :在乌尔皇家墓地发现的五块游戏板之一

两名玩家每人从家中的七个代币开始,第一个将所有七个代币移动到目标位置的玩家获胜。玩家轮流掷出四个骰子。这些骰子是称为四面体的四角金字塔形状。每个骰子都有两个标记点,这使得骰子有标记或无标记的机会均等。我们的游戏用硬币代替骰子,硬币的头部作为标记点。玩家可以为出现的每一个标记点移动一格代币。这意味着他们可以在 0 到 4 个空格之间移动一个代币,尽管他们最有可能掷出两个空格。

代币沿着图 63-2 中所示的路径行进。一个空间上一次只能存在一个代币。如果一个代币在共享中间路径上落在对手的代币上,对手的代币会被送回家。如果一个代币落在中间的花方格上,它就不会被落在上面。如果一个代币落在其他四个花牌中的任何一个上,玩家可以再掷一次。我们的游戏将用字母XO来代表代币。

Python 小型项目大全 61~65_第7张图片

图 63-2 :每个玩家的代币从他们的家到他们的目标的路径

www.youtube.com/watch?v=WZskjLq040I可以找到优图伯·汤姆·斯科特和大英博物馆馆长欧文·芬克尔讨论乌尔王族游戏的视频。

运行示例

当您运行royalgameofur.py时,输出将如下所示:

The Royal Game of Ur, by Al Sweigart
`--snip--`
                   XXXXXXX           .......
                   Home              Goal
                     v                 ^
+-----+-----+-----+--v--+           +--^--+-----+
|*****|     |     |     |           |*****|     |
|*   *<     <     <     |           |*   *<     |
|****h|    g|    f|    e|           |****t|    s|
+--v--+-----+-----+-----+-----+-----+-----+--^--+
|     |     |     |*****|     |     |     |     |
|     >     >     >*   *>     >     >     >     |
|    i|    j|    k|****l|    m|    n|    o|    p|
+--^--+-----+-----+-----+-----+-----+-----+--v--+
|*****|     |     |     |           |*****|     |
|*   *<     <     <     |           |*   *<     |
|****d|    c|    b|    a|           |****r|    q|
+-----+-----+-----+--^--+           +--v--+-----+
                     ^                 v
                   Home              Goal
                   OOOOOOO           .......

It is O's turn. Press Enter to flip...
Flips: H-H-H-H  Select token to move 4 spaces: home quit
> home
O landed on a flower space and gets to go again.
Press Enter to continue...
`--snip--`

工作原理

就像项目 43“曼卡拉”一样,ASCII 艺术画游戏棋盘上的空格用字母at标注。掷骰子后,玩家可以选择一个包含其代币的空间来移动代币,或者他们可以选择home开始将代币从家中移到棋盘上。该程序将棋盘表示为一个字典,其中键为'a''t',值为'X''O'用于标记(或' '用于空格)。

此外,这个字典有关键字'x_home''o_home''x_goal''o_goal',这些关键字的值是七个字符的字符串,表示家庭和目标有多满。这些字符串中的'X''O'字符代表主场或球门的代币,'.'代表空位置。displayBoard()函数在屏幕上显示这七个字符串。

"""The Royal Game of Ur, by Al Sweigart email@protected
A 5,000 year old board game from Mesopotamia. Two players knock each
other back as they race for the goal.
More info https://en.wikipedia.org/wiki/Royal_Game_of_Ur
This code is available at https://nostarch.com/big-book-small-python-programming
Tags: large, board game, game, two-player
"""

import random, sys

X_PLAYER = 'X'
O_PLAYER = 'O'
EMPTY = ' '

# Set up constants for the space labels:
X_HOME = 'x_home'
O_HOME = 'o_home'
X_GOAL = 'x_goal'
O_GOAL = 'o_goal'

# The spaces in left to right, top to bottom order:
ALL_SPACES = 'hgfetsijklmnopdcbarq'
X_TRACK = 'HefghijklmnopstG'  # (H stands for Home, G stands for Goal.)
O_TRACK = 'HabcdijklmnopqrG'

FLOWER_SPACES = ('h', 't', 'l', 'd', 'r')

BOARD_TEMPLATE = """
{}  {} 30\.                   Home              Goal
                    v                 ^
+-----+-----+-----+--v--+           +--^--+-----+
|*****|     |     |     |           |*****|     |
|* {} *< {} < {} < {} |           |* {} *< {} |
|****h|    g|    f|    e|           |****t|    s|
+--v--+-----+-----+-----+-----+-----+-----+--^--+
|     |     |     |*****|     |     |     |     |
| {} > {} > {} >* {} *> {} > {} > {} > {} |
|    i|    j|    k|****l|    m|    n|    o|    p|
+--^--+-----+-----+-----+-----+-----+-----+--v--+
|*****|     |     |     |           |*****|     |
|* {} *< {} < {} < {} |           |* {} *< {} |
|****d|    c|    b|    a|           |****r|    q|
+-----+-----+-----+--^--+           +--v--+-----+
                    ^                 v
                  Home              Goal
{}  {} 48\. """


def main():
   print('''The Royal Game of Ur, by Al Sweigart

This is a 5,000 year old game. Two players must move their tokens
from their home to their goal. On your turn you flip four coins and can
move one token a number of spaces equal to the heads you got.

Ur is a racing game; the first player to move all seven of their tokens
to their goal wins. To do this, tokens must travel from their home to
their goal:

           X Home      X Goal
             v           ^
+---+---+---+-v-+       +-^-+---+
|v<<<<<<<<<<<<< |       | ^<|<< |
|v  |   |   |   |       |   | ^ |
+v--+---+---+---+---+---+---+-^-+
|>>>>>>>>>>>>>>>>>>>>>>>>>>>>>^ |
|>>>>>>>>>>>>>>>>>>>>>>>>>>>>>v |
+^--+---+---+---+---+---+---+-v-+
|^  |   |   |   |       |   | v |
|^<<<<<<<<<<<<< |       | v<<<< |
+---+---+---+-^-+       +-v-+---+
             ^           v
           O Home      O Goal

If you land on an opponent's token in the middle track, it gets sent
back home. The **flower** spaces let you take another turn. Tokens in
the middle flower space are safe and cannot be landed on.''')
   input('Press Enter to begin...')

   gameBoard = getNewBoard()
   turn = O_PLAYER
   while True:  # Main game loop.
       # Set up some variables for this turn:
       if turn == X_PLAYER:
           opponent = O_PLAYER
           home = X_HOME
           track = X_TRACK
           goal = X_GOAL
           opponentHome = O_HOME
       elif turn == O_PLAYER:
           opponent = X_PLAYER
           home = O_HOME
           track = O_TRACK
           goal = O_GOAL
           opponentHome = X_HOME

       displayBoard(gameBoard)

        input('It is ' + turn + '\'s turn. Press Enter to flip...')

        flipTally = 0
        print('Flips: ', end='')
        for i in range(4):  # Flip 4 coins.
            result = random.randint(0, 1)
            if result == 0:
                print('T', end='')  # Tails.
            else:
                print('H', end='')  # Heads.
            if i != 3:
                print('-', end='')  # Print separator.
            flipTally += result
        print('  ', end='')

        if flipTally == 0:
            input('You lose a turn. Press Enter to continue...')
            turn = opponent  # Swap turns to the other player.
            continue

        # Ask the player for their move:
        validMoves = getValidMoves(gameBoard, turn, flipTally)

        if validMoves == []:
            print('There are no possible moves, so you lose a turn.')
            input('Press Enter to continue...')
            turn = opponent  # Swap turns to the other player.
            continue

        while True:
            print('Select move', flipTally, 'spaces: ', end='')
            print(' '.join(validMoves) + ' quit')
            move = input('> ').lower()

            if move == 'quit':
                print('Thanks for playing!')
                sys.exit()
            if move in validMoves:
                break  # Exit the loop when a valid move is selected.

            print('That is not a valid move.')

        # Perform the selected move on the board:
        if move == 'home':
            # Subtract tokens at home if moving from home:
            gameBoard[home] -= 1
            nextTrackSpaceIndex = flipTally
        else:
            gameBoard[move] = EMPTY  # Set the "from" space to empty.
            nextTrackSpaceIndex = track.index(move) + flipTally

        movingOntoGoal = nextTrackSpaceIndex == len(track) - 1
        if movingOntoGoal:
            gameBoard[goal] += 1
            # Check if the player has won:
            if gameBoard[goal] == 7:
                displayBoard(gameBoard)
                print(turn, 'has won the game!')
                print('Thanks for playing!')
                sys.exit()
        else:
            nextBoardSpace = track[nextTrackSpaceIndex]
            # Check if the opponent has a tile there:
            if gameBoard[nextBoardSpace] == opponent:
                gameBoard[opponentHome] += 1

            # Set the "to" space to the player's token:
            gameBoard[nextBoardSpace] = turn

        # Check if the player landed on a flower space and can go again:
        if nextBoardSpace in FLOWER_SPACES:
            print(turn, 'landed on a flower space and goes again.')
            input('Press Enter to continue...')
        else:
            turn = opponent  # Swap turns to the other player.

def getNewBoard():
    """
    Returns a dictionary that represents the state of the board. The
    keys are strings of the space labels, the values are X_PLAYER,
    O_PLAYER, or EMPTY. There are also counters for how many tokens are
    at the home and goal of both players.
    """
    board = {X_HOME: 7, X_GOAL: 0, O_HOME: 7, O_GOAL: 0}
    # Set each space as empty to start:
    for spaceLabel in ALL_SPACES:
        board[spaceLabel] = EMPTY
    return board


def displayBoard(board):
    """Display the board on the screen."""
    # "Clear" the screen by printing many newlines, so the old
    # board isn't visible anymore.
    print('\n' * 60)

    xHomeTokens = ('X' * board[X_HOME]).ljust(7, '.')
    xGoalTokens = ('X' * board[X_GOAL]).ljust(7, '.')
    oHomeTokens = ('O' * board[O_HOME]).ljust(7, '.')
    oGoalTokens = ('O' * board[O_GOAL]).ljust(7, '.')

    # Add the strings that should populate BOARD_TEMPLATE in order,
    # going from left to right, top to bottom.
    spaces = []
    spaces.append(xHomeTokens)
    spaces.append(xGoalTokens)
    for spaceLabel in ALL_SPACES:
        spaces.append(board[spaceLabel])
    spaces.append(oHomeTokens)
    spaces.append(oGoalTokens)

    print(BOARD_TEMPLATE.format(*spaces))


def getValidMoves(board, player, flipTally):
    validMoves = []  # Contains the spaces with tokens that can move.
    if player == X_PLAYER:
        opponent = O_PLAYER
        track = X_TRACK
        home = X_HOME
    elif player == O_PLAYER:
        opponent = X_PLAYER
        track = O_TRACK
        home = O_HOME

    # Check if the player can move a token from home:
    if board[home] > 0 and board[track[flipTally]] == EMPTY:
        validMoves.append('home')

    # Check which spaces have a token the player can move:
    for trackSpaceIndex, space in enumerate(track):
        if space == 'H' or space == 'G' or board[space] != player:
            continue
        nextTrackSpaceIndex = trackSpaceIndex + flipTally
        if nextTrackSpaceIndex >= len(track):
            # You must flip an exact number of moves onto the goal,
            # otherwise you can't move on the goal.
            continue
        else:
            nextBoardSpaceKey = track[nextTrackSpaceIndex]
            if nextBoardSpaceKey == 'G':
                # This token can move off the board:
                validMoves.append(space)
                continue
        if board[nextBoardSpaceKey] in (EMPTY, opponent):
            # If the next space is the protected middle space, you
            # can only move there if it is empty:
            if nextBoardSpaceKey == 'l' and board['l'] == opponent:
                continue  # Skip this move, the space is protected.
            validMoves.append(space)

    return validMoves


if __name__ == '__main__':
    main() 

探索程序

试着找出下列问题的答案。尝试对代码进行一些修改,然后重新运行程序,看看这些修改有什么影响。

  1. 如果把 152 行的nextTrackSpaceIndex == len(track) - 1改成nextTrackSpaceIndex == 1会怎么样?
  2. 如果把 106 行的result = random.randint(0, 1)改成result = 1会怎么样?
  3. 如果把 184 行的board = {X_HOME: 7, X_GOAL: 0, O_HOME: 7, O_GOAL: 0}改成board = {}会导致什么错误?

六十四、七段显示模块

原文:http://inventwithpython.com/bigbookpython/project64.html

Python 小型项目大全 61~65_第8张图片

七段显示器是一种 LCD 组件,用于在袖珍计算器、微波炉和其他小型电子设备中显示数字。通过 LCD 中七个线段的不同组合,七段显示器可以表示数字 0 到 9。它们看起来像这样:

   __         __    __          __    __   __    __    __
  |  |    |   __|   __|  |__|  |__   |__     |  |__|  |__|
  |__|    |  |__    __|     |   __|  |__|    |  |__|   __|

这个程序的好处是其他程序可以把它作为一个模块导入。项目 14,“倒计时”和项目 19,“数字钟”,导入sevseg.py文件,这样他们就可以使用它的getSevSegStr()函数。你可以在en.wikipedia.org/wiki/Seven-segment_display找到更多关于七段显示器和其他变化的信息。

运行示例

尽管它是一个模块,当你直接运行程序时,sevseg.py输出一个它产生的数字的示例演示。输出将如下所示:

This module is meant to be imported rather than run.
For example, this code:
    import sevseg
    myNumber = sevseg.getSevSegStr(42, 3)
    print(myNumber)

Will print 42, zero-padded to three digits:
 __        __
|  | |__|  __|
|__|    | |__

工作原理

getSevSegStr()函数首先创建一个包含三个字符串的列表。这些字符串表示数字的顶行、中间行和底行。第 27 行到第 75 行有一长串针对每个数字(以及小数点和减号)的if - elif语句,这些语句将每个数字的行连接到这些字符串。这三个字符串在第 84 行用换行符连接在一起,因此函数返回一个适合传递给print()的多行字符串。

"""Sevseg, by Al Sweigart email@protected
A seven-segment number display module, used by the Countdown and Digital
Clock programs.
More info at https://en.wikipedia.org/wiki/Seven-segment_display
This code is available at https://nostarch.com/big-book-small-python-programming
Tags: short, module"""

"""A labeled seven-segment display, with each segment labeled A to G:
__A__
|     |    Each digit in a seven-segment display:
F     B     __       __   __        __   __  __   __   __
|__G__|    |  |   |  __|  __| |__| |__  |__    | |__| |__|
|     |    |__|   | |__   __|    |  __| |__|   | |__|  __|
E     C
|__D__|"""


def getSevSegStr(number, minWidth=0):
   """Return a seven-segment display string of number. The returned
   string will be padded with zeros if it is smaller than minWidth."""

   # Convert number to string in case it's an int or float:
   number = str(number).zfill(minWidth)

   rows = ['', '', '']
   for i, numeral in enumerate(number):
       if numeral == '.':  # Render the decimal point.
           rows[0] += ' '
           rows[1] += ' '
           rows[2] += '.'
           continue  # Skip the space in between digits.
       elif numeral == '-':  # Render the negative sign:
           rows[0] += '    '
           rows[1] += ' __ '
           rows[2] += '    '
       elif numeral == '0':  # Render the 0.
           rows[0] += ' __ '
           rows[1] += '|  |'
           rows[2] += '|__|'
       elif numeral == '1':  # Render the 1.
           rows[0] += '    '
           rows[1] += '   |'
           rows[2] += '   |'
       elif numeral == '2':  # Render the 2.
           rows[0] += ' __ '
           rows[1] += ' __|'
           rows[2] += '|__ '
       elif numeral == '3':  # Render the 3.
           rows[0] += ' __ '
           rows[1] += ' __|'
           rows[2] += ' __|'
       elif numeral == '4':  # Render the 4.
           rows[0] += '    '
           rows[1] += '|__|'
           rows[2] += '   |'
       elif numeral == '5':  # Render the 5.
           rows[0] += ' __ '
           rows[1] += '|__ '
           rows[2] += ' __|'
       elif numeral == '6':  # Render the 6.
           rows[0] += ' __ '
           rows[1] += '|__ '
           rows[2] += '|__|'
       elif numeral == '7':  # Render the 7.
           rows[0] += ' __ '
           rows[1] += '   |'
           rows[2] += '   |'
       elif numeral == '8':  # Render the 8.
           rows[0] += ' __ '
           rows[1] += '|__|'
           rows[2] += '|__|'
       elif numeral == '9':  # Render the 9.
           rows[0] += ' __ '
           rows[1] += '|__|'
           rows[2] += ' __|'

       # Add a space (for the space in between numerals) if this
       # isn't the last numeral and the decimal point isn't next:
       if i != len(number) - 1 and number[i + 1] != '.':
           rows[0] += ' '
           rows[1] += ' '
           rows[2] += ' '

   return '\n'.join(rows)


# If this program isn't being imported, display the numbers 00 to 99.
if __name__ == '__main__':
   print('This module is meant to be imported rather than run.')
   print('For example, this code:')
   print('    import sevseg')
   print('    myNumber = sevseg.getSevSegStr(42, 3)')
   print('    print(myNumber)')
   print()
   print('...will print 42, zero-padded to three digits:')
   print(' __        __ ')
   print('|  | |__|  __|')
   print('|__|    | |__ ') 

在输入源代码并运行几次之后,尝试对其进行实验性的修改。你也可以自己想办法做到以下几点:

  • 为数字创建新的字体,比如使用五行和chr(9608)返回的块字符串。
  • 查看维基百科关于七段显示的文章,了解如何显示字母,然后将它们添加到sevseg.py
  • en.wikipedia.org/wiki/Sixteen-segment_display学习十六段显示,并创建一个十六段显示模块来生成该样式的数字。

探索程序

试着找出下列问题的答案。尝试对代码进行一些修改,然后重新运行程序,看看这些修改有什么影响。

  1. 如果将第 80、81 和 82 行的单空格字符串改为空字符串会发生什么?
  2. 如果将第 18 行的默认参数minWidth=0改为minWidth=8,会发生什么?

六十五、闪光地毯

原文:http://inventwithpython.com/bigbookpython/project65.html

Python 小型项目大全 61~65_第9张图片

斯坦利·库布里克执导的 1980 年心理恐怖片《闪光》发生在闹鬼的远眺酒店。酒店地毯的六边形设计成为这部著名电影的标志性部分。地毯的特点是交替和连锁的六边形,其催眠效果非常适合这样一部令人紧张的电影。这个项目中的短程序,类似于项目 35,“六边形网格”,在屏幕上打印这个重复的图案。

注意,这个程序使用原始字符串,它在开始的引号前面加上小写的r,这样字符串中的反斜杠就不会被解释为转义字符。

运行示例

当您运行shiningcarpet.py时,输出将如下所示:

_ \ \ \_/ ___ \ \ \_/ ___ \ \ \_/ ___ \ \ \_/ ___ \ \ \_/ ___ \ \ \_/ __
 \ \ \___/ _ \ \ \___/ _ \ \ \___/ _ \ \ \___/ _ \ \ \___/ _ \ \ \___/ _
\ \ \_____/ \ \ \_____/ \ \ \_____/ \ \ \_____/ \ \ \_____/ \ \ \_____/
/ / / ___ \_/ / / ___ \_/ / / ___ \_/ / / ___ \_/ / / ___ \_/ / / ___ \_
_/ / / _ \___/ / / _ \___/ / / _ \___/ / / _ \___/ / / _ \___/ / / _ \__
__/ / / \_____/ / / \_____/ / / \_____/ / / \_____/ / / \_____/ / / \___
_ \ \ \_/ ___ \ \ \_/ ___ \ \ \_/ ___ \ \ \_/ ___ \ \ \_/ ___ \ \ \_/ __
 \ \ \___/ _ \ \ \___/ _ \ \ \___/ _ \ \ \___/ _ \ \ \___/ _ \ \ \___/ _
\ \ \_____/ \ \ \_____/ \ \ \_____/ \ \ \_____/ \ \ \_____/ \ \ \_____/
/ / / ___ \_/ / / ___ \_/ / / ___ \_/ / / ___ \_/ / / ___ \_/ / / ___ \_
_/ / / _ \___/ / / _ \___/ / / _ \___/ / / _ \___/ / / _ \___/ / / _ \__
__/ / / \_____/ / / \_____/ / / \_____/ / / \_____/ / / \_____/ / / \___
_ \ \ \_/ ___ \ \ \_/ ___ \ \ \_/ ___ \ \ \_/ ___ \ \ \_/ ___ \ \ \_/ __
 \ \ \___/ _ \ \ \___/ _ \ \ \___/ _ \ \ \___/ _ \ \ \___/ _ \ \ \___/ _
\ \ \_____/ \ \ \_____/ \ \ \_____/ \ \ \_____/ \ \ \_____/ \ \ \_____/
/ / / ___ \_/ / / ___ \_/ / / ___ \_/ / / ___ \_/ / / ___ \_/ / / ___ \_
_/ / / _ \___/ / / _ \___/ / / _ \___/ / / _ \___/ / / _ \___/ / / _ \__
__/ / / \_____/ / / \_____/ / / \_____/ / / \_____/ / / \_____/ / / \___

工作原理

创建这样的程序(或类似的第三十五个项目)并不是从编码开始,而是在文本编辑器中绘制镶嵌形状。一旦你写出了图案,你就可以把它切割成需要平铺的最小单元:

_ \ \ \_/ __
 \ \ \___/ _
\ \ \_____/
/ / / ___ \_
_/ / / _ \__
__/ / / \___

将这段文本复制并粘贴到源代码中后,您可以围绕它编写程序的其余部分。软件不仅仅是坐下来从头到尾写代码。每个专业软件开发人员都要经历几次反复的修补、实验和调试。最终的结果可能只有九行代码,但是一个小程序并不一定意味着花了很少的精力来完成它。

"""Shining Carpet, by Al Sweigart email@protected
Displays a tessellation of the carpet pattern from The Shining.
This code is available at https://nostarch.com/big-book-small-python-programming
Tags: tiny, beginner, artistic"""

# Set up the constants:
X_REPEAT = 6  # How many times to tessellate horizontally.
Y_REPEAT = 4  # How many times to tessellate vertically.

for i in range(Y_REPEAT):
    print(r'_ \ \ \_/ __' * X_REPEAT)
    print(r' \ \ \___/ _' * X_REPEAT)
    print(r'\ \ \_____/ ' * X_REPEAT)
    print(r'/ / / ___ \_' * X_REPEAT)
    print(r'_/ / / _ \__' * X_REPEAT)
    print(r'__/ / / \___' * X_REPEAT) 

探索程序

在实践中,尝试创建如下模式:

___|___|___|___|___|___|___|___|___|___|___|___|___|___|___|
_|___|___|___|___|___|___|___|___|___|___|___|___|___|___|__
___|___|___|___|___|___|___|___|___|___|___|___|___|___|___|
_|___|___|___|___|___|___|___|___|___|___|___|___|___|___|__
___|___|___|___|___|___|___|___|___|___|___|___|___|___|___|
_|___|___|___|___|___|___|___|___|___|___|___|___|___|___|__

((  )((  )((  )((  )((  )((  )((  )((  )((  )((  )((  )((  )
 ))(  ))(  ))(  ))(  ))(  ))(  ))(  ))(  ))(  ))(  ))(  ))(
((  )((  )((  )((  )((  )((  )((  )((  )((  )((  )((  )((  )
 ))(  ))(  ))(  ))(  ))(  ))(  ))(  ))(  ))(  ))(  ))(  ))(
((  )((  )((  )((  )((  )((  )((  )((  )((  )((  )((  )((  )
 ))(  ))(  ))(  ))(  ))(  ))(  ))(  ))(  ))(  ))(  ))(  ))(

 / __ \ \__/ / __ \ \__/ / __ \ \__/ / __ \ \__/ / __ \ \__/
/ /  \ \____/ /  \ \____/ /  \ \____/ /  \ \____/ /  \ \____
\ \__/ / __ \ \__/ / __ \ \__/ / __ \ \__/ / __ \ \__/ / __
 \____/ /  \ \____/ /  \ \____/ /  \ \____/ /  \ \____/ /  \
 / __ \ \__/ / __ \ \__/ / __ \ \__/ / __ \ \__/ / __ \ \__/
/ /  \ \____/ /  \ \____/ /  \ \____/ /  \ \____/ /  \ \____
\ \__/ / __ \ \__/ / __ \ \__/ / __ \ \__/ / __ \ \__/ / __
 \____/ /  \ \____/ /  \ \____/ /  \ \____/ /  \ \____/ /  \

  \__   \__   \__   \__   \__   \__   \__   \__   \__   \__
__/  \__/  \__/  \__/  \__/  \__/  \__/  \__/  \__/  \__/  \
  \     \     \     \     \     \     \     \     \     \
__/   __/   __/   __/   __/   __/   __/   __/   __/   __/
  \__/  \__/  \__/  \__/  \__/  \__/  \__/  \__/  \__/  \__/
__/     /     /     /     /     /     /     /     /     /
  \__   \__   \__   \__   \__   \__   \__   \__   \__   \__
__/  \__/  \__/  \__/  \__/  \__/  \__/  \__/  \__/  \__/  \

/ ___ \ ^ / ___ \ ^ / ___ \ ^ / ___ \ ^ / ___ \ ^ / ___ \ ^
 /   \ VVV /   \ VVV /   \ VVV /   \ VVV /   \ VVV /   \ VVV
|() ()|   |() ()|   |() ()|   |() ()|   |() ()|   |() ()|
 \ ^ / ___ \ ^ / ___ \ ^ / ___ \ ^ / ___ \ ^ / ___ \ ^ / ___
\ VVV /   \ VVV /   \ VVV /   \ VVV /   \ VVV /   \ VVV /
)|   |() ()|   |() ()|   |() ()|   |() ()|   |() ()|   |() (

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