python入门及进阶学习记 lesson1

2021-08-11 02:43:53

下载:

cmd中查看版本及使用

Python 教程
Python是一种易于学习又功能强大的编程语言,它提供了高效的高级数据结构,还有简单有效的面向对象编程.
Python优雅的语法和动态类型, 以及解释型语言的本质, 使它成为多数平台上写脚本和快速开发应用的理想语言.

Python解释器及丰富的标准库以源码或机器码的形式提供, 可以到Python官网免费获取适用于各个主要系统平台的版本, 并可*地分发. 这个网站还包含许多免费第三方Python模块,程序和工具以及附加文档的发布页面或链接.

Python解释器易于扩展, 可以使用C或C++ (或其它可以通过C调用的语言) 扩展新的功能和数据类型. Python也可用于可定制化软件中的扩展程序语言.

这个教程非正式地介绍Python语言和系统的基本概念和功能, 最好在阅读的时候备一个Python解释器进行练习, 不过所有的例子都是相互独立的, suo

有关标准的对象和模块，参阅 Python 标准库。Python 语言参考提供了更正式的语言参考。想要编写 C 或者 C++ 扩展可以参考扩展和嵌入 Python 解释器和 Python/C API 参考手册。也有不少书籍深入讲解Python 。

对python的了解程度

Python是一个简洁和强大的面向对象的编程语言.可以与Perl,Ruby,Scheme,Java比较.

Python的一些特点:

使用优雅的语法格式,让你的Python程序代码更加易读.
是一种易于使用的语言，使您的程序工作起来很简单。这使得Python在不损害可维护性的情况下，成为原型开发和其他特殊编程任务的理想选择。
附带一个大型标准库，支持许多常见的编程任务，如连接到web服务器、使用正则表达式搜索文本、读取和修改文件。
Python的交互模式使测试短代码段变得很容易。还有一个捆绑的开发环境称为IDLE。
通过添加用编译语言(如C或c++)实现的新模块，可以很容易地进行扩展。
也可以嵌入到应用程序中提供可编程接口。
可以在任何地方运行，包括Mac OS X、Windows、Linux和Unix，Android和iOS也有非官方版本。
从两个意义上说，它是*软件。下载或使用Python，或将其包含在应用程序中，都不需要任何成本。Python还可以*修改和重新分发，因为虽然该语言是受版权保护的，但它是在开放源码许可下可用的。

Python的一些编程语言特性包括:

可以使用多种基本数据类型:数字(浮点数、复杂的和无限制长度的长整数)、字符串(ASCII和Unicode)、列表和字典。
Python支持使用类和多重继承进行面向对象编程。
代码可以分为模块和包。
该语言支持引发和捕获异常，从而实现更清晰的错误处理。
数据类型是强类型和动态类型。混合不兼容的类型(例如试图添加字符串和数字)会引发异常，因此错误会更快被捕获。
Python包含高级编程特性，如生成器和列表理解。
Python的自动内存管理使您不必在代码中手动分配和释放内存。

查看Python程序示例代码:
请注意，这些示例是用python2编写的，可能需要一些调整才能在python3下运行。

1 line : Output 输出

print 'Hello, world!'

2 lines : Input 输入, assignment 赋值

name = raw_input('What is your name?\n')
print 'Hi, %s.' % name

↑详见2to3

术语对照表

交互式终端中默认的Python提示符. 往往会显示于能以交互方式在解释器里执行的样式代码之前.

交互式终端中输入特殊代码行时默认的Python提示符, 包括: 缩进的代码块, 成对的分隔符之内 (圆括号,方括号, 花括号或三重引号) , 或是指定一个装饰器之后.

2to3
一个将 Python 2.x 代码转换为 Python 3.x 代码的工具,能够处理大部分通过解析源码并遍历解析树可检测到的不兼容问题.

2to3 包含在标准库中, 模块名为 lib2to3; 并提供一个独立入口点 Tools/scripts/2to3 .
2to3 - 自动将 Python 2 代码转为 Python 3 代码

2to3 的使用

2to3 通常会作为脚本和Python解释器一起安装,你可以在Python根目录的Tools/scripts文件夹下找到它.
2to3 的基本调用参数是一个需要转换的文件或目录列表. 对于目录, 会递归地寻找其中的Python源码.
使用命令:

2to3 example.py

这个命令会打印出和源文件的区别, 通过传入-w参数, 2to3 也可以把需要的改写写回到原文件中 (除非传入了 -n 参数, 否则会为原始文件创建一个副本):

2to3 -w example.py

就拿示例代码中的来进行转换测试: https://wiki.python.org/moin/SimplePrograms
一般这个示例代码是Python2中的

name = raw_input('What is your name?\n')
print 'Hi, %s.' % name

保存文件后执行2to3命令(需要将2to3的工具放入系统中才能快速使用)
例如 : F:\python3.7\Tools\scripts
执行时添加 -w 参数

2to3 -w inputName.py

会产生一个原件副本,执行后原本名称的已经更改了:

name = input('What is your name?\n')
print('Hi, %s.' % name)

执行输出:

3 lines : For loop (循环) , built-in enumerate function (内置枚举函数), new style formatting (新样式格式化)

friends = ['join','pat','gary','michael']
for i,name in enumerate(friends):
    print "iteration {iteration} is {name}".format(iteration=i,name=name)

2to3后:

friends = ['jack','kyo','ukyo','lucy']
for i,name in enumerate(friends):
    print("iteration {iteration} is {name}".format(iteration=i,name=name))

之后的一直使用Python 3的示例:
4 lines : Fibonacci (斐波那契数列), tuple assignment (元组赋值)

parents, babies = (1,1)
while babies < 100:
    print('This generation has {0} babies'.format(babies))
    parents, babies = (babies, parents + babies)

5 lines : Functions (方法)

def greet(name):
    print('Hello',name)
greet('Jack')
greet('Lucy')
greet('alibaba')

6 lines : Import(导入依赖), regular expressions(正则表达式)

import re
for test_string in ['555-1212','ILL-EGAL']:
    if re.match(r'^\d{3}-\d{4}$',test_string):
        print(test_string, 'is a valid US local phone number')
    else:
        print(test_string, 'rejected')

7 lines: Dictionaries(字典), generator expressions (生成表达式)

prices = {'apple':0.40, 'banana':0.50}
my_purchase = {
    'apple':1,
    'banana':6}
grocery_bill = sum(prices[fruit] * my_purchase[fruit]
                   for fruit in my_purchase)
print('I owe the grocer $%.2f' % grocery_bill)

8 lines : Command line arguments(命令行参数) , exception handling(异常处理)

# This program adds up integers in the command line
import sys
try:
    total = sum(int(arg) for arg in sys.argv[1:])
    print('sum =', total)
except ValueError:
    print('Please supply integer arguments')

9 lines : Opening files (打开文件)

# indent your Python code to put into an email
import glob
# glob supports Unix style pathname extensions
python_files = glob.glob('*.py')
for file_name in sorted(python_files):
    print(' -------' + file_name)

    with open(file_name) as f:
        for line in f:
            print('     ' + line.rstrip())

    print()

10 lines : Time(时间), conditionals(条件表达式), from…import( from…import ), for…else( for…else )

from time import localtime

activities = {8: 'Sleeping',
              9: 'Commuting',
              17: 'Working',
              18: 'Commuting',
              20: 'Eating',
              22: 'Resting'}

time_now = localtime()
hour = time_now.tm_hour

for activity_time in sorted(activities.keys()):
    if hour < activity_time:
        print(activities[activity_time])
        break
else:
    print('Unknown,AFK or sleeping!')

11 lines : Triple-quoted strings (三引号字符串), while loop(while循环)

REFRAIN = '''
%d bottles of beer on the wall,
%d bottles of beer,
take one down, pass it around,
%d bottles of beer on the wall!
'''
bottles_of_beer = 99
while bottles_of_beer > 1:
    print(REFRAIN % (bottles_of_beer, bottles_of_beer,
        bottles_of_beer - 1))
    bottles_of_beer -= 1

12 lines : Classes (类)

class BankAccount(object):
    def __init__(self, initial_balance=0):
        self.balance = initial_balance
    def deposit(self, amount):
        self.balance += amount
    def withdraw(self, amount):
        self.balance -= amount
    def overdrawn(self):
        return self.balance < 0
my_account = BankAccount(15)
my_account.withdraw(5)
print my_account.balance

13 lines : Unit testing with unittest (使用unittest模块进行单元测试)

import unittest
def median(pool):
    copy = sorted(pool)
    size = len(copy)
    if size % 2 == 1:
        return copy[(size - 1) / 2]
    else:
        return (copy[size/2 - 1] + copy[size/2]) / 2
class TestMedian(unittest.TestCase):
    def testMedian(self):
        self.assertEqual(median([2,9,9,7,9,2,4,5,8]),7)
if __name__ == '__main__':
    unittest.main()

千万不要把py文件的名字命名为模块名
14 lines : Doctest-based testing(基础文档测试)

def median(pool):
    '''Statistical median to demonstrate doctest.
    >>> median([2, 9, 9, 7, 9, 2, 4, 5, 8])
    7
    '''
    copy = sorted(pool)
    size = len(copy)
    if size % 2 == 1:
        return copy[(size - 1) / 2]
    else:
        return (copy[size/2 - 1] + copy[size/2]) / 2
if __name__ == '__main__':
    import doctest
    doctest.testmod()

15 lines : itertools (迭代器)

from itertools import groupby
lines = '''
This is the
first paragraph.

This is the second.
'''.splitlines()
# Use itertools.groupby and bool to return groups of
# consecutive lines that either have content or don't.
for has_chars, frags in groupby(lines,bool):
    if has_chars:
        print(' '.join(frags))
# PRINTS:
# This is the first paragraph.
# This is the second.

16 lines : csv module (csv模块), tuple unpacking(元组分解) , cmp() built-in(cmp()内置)
应该从16开始了 https://wiki.python.org/moin/SimplePrograms
调试了下还是报错:希望之后能再次遇到并解决

import csv

# write stocks data as comma-separated values
from filecmp import cmp

writer = csv.writer(open('stocks.csv','wb',buffering=0))
writer.writerows([
    ('YHOO'.encode(),'YaHoo! Inc.'.encode(),27.38,0.33,1.22),
])

# read stocks data, print status messages
stocks = csv.reader(open('stocks.csv','rb'))
status_labels = {-1:'down',0:'unchanged',1:'up'}
for ticker,name,price,change,pct in stocks:
    status = status_labels[cmp(float(change),0.0)]
    print('%s is %s (%s%%)' % (name,status,pct))

错误日志:

Traceback (most recent call last):
  File "E:/pyCharmFiles/csvtest.py", line 8, in <module>
    ('YHOO'.encode(),'YaHoo! Inc.'.encode(),27.38,0.33,1.22),
TypeError: a bytes-like object is required, not 'str'

18 lines : 8-Queens Problem (recursion) (8皇后递归问题)

BOARD_SIZE = 8

def under_attack(col,queens):
    left = right = col

    for r, c in reversed(queens):
        left, right = left - 1, right + 1

        if c in (left, col, right):
            return True
    return False

def solve(n):
    if n == 0:
        return [[]]

    smaller_solutions = solve(n - 1)

    return [solution+[(n,i+1)]
        for i in range(BOARD_SIZE)
            for solution in smaller_solutions
                if not under_attack(i+1,solution)]
for answer in solve(BOARD_SIZE):
    print(answer)

8皇后的问题要持续关注下
打印的输出比较有趣:

E:\pyCharmFiles\venv\Scripts\python.exe E:/pyCharmFiles/SimplePrograms/8Queens.py
[(1, 4), (2, 2), (3, 7), (4, 3), (5, 6), (6, 8), (7, 5), (8, 1)]
[(1, 5), (2, 2), (3, 4), (4, 7), (5, 3), (6, 8), (7, 6), (8, 1)]
[(1, 3), (2, 5), (3, 2), (4, 8), (5, 6), (6, 4), (7, 7), (8, 1)]
[(1, 3), (2, 6), (3, 4), (4, 2), (5, 8), (6, 5), (7, 7), (8, 1)]
[(1, 5), (2, 7), (3, 1), (4, 3), (5, 8), (6, 6), (7, 4), (8, 2)]
[(1, 4), (2, 6), (3, 8), (4, 3), (5, 1), (6, 7), (7, 5), (8, 2)]
[(1, 3), (2, 6), (3, 8), (4, 1), (5, 4), (6, 7), (7, 5), (8, 2)]
[(1, 5), (2, 3), (3, 8), (4, 4), (5, 7), (6, 1), (7, 6), (8, 2)]
[(1, 5), (2, 7), (3, 4), (4, 1), (5, 3), (6, 8), (7, 6), (8, 2)]
[(1, 4), (2, 1), (3, 5), (4, 8), (5, 6), (6, 3), (7, 7), (8, 2)]
[(1, 3), (2, 6), (3, 4), (4, 1), (5, 8), (6, 5), (7, 7), (8, 2)]
[(1, 4), (2, 7), (3, 5), (4, 3), (5, 1), (6, 6), (7, 8), (8, 2)]
[(1, 6), (2, 4), (3, 2), (4, 8), (5, 5), (6, 7), (7, 1), (8, 3)]
[(1, 6), (2, 4), (3, 7), (4, 1), (5, 8), (6, 2), (7, 5), (8, 3)]
[(1, 1), (2, 7), (3, 4), (4, 6), (5, 8), (6, 2), (7, 5), (8, 3)]
[(1, 6), (2, 8), (3, 2), (4, 4), (5, 1), (6, 7), (7, 5), (8, 3)]
[(1, 6), (2, 2), (3, 7), (4, 1), (5, 4), (6, 8), (7, 5), (8, 3)]
[(1, 4), (2, 7), (3, 1), (4, 8), (5, 5), (6, 2), (7, 6), (8, 3)]
[(1, 5), (2, 8), (3, 4), (4, 1), (5, 7), (6, 2), (7, 6), (8, 3)]
[(1, 4), (2, 8), (3, 1), (4, 5), (5, 7), (6, 2), (7, 6), (8, 3)]
[(1, 2), (2, 7), (3, 5), (4, 8), (5, 1), (6, 4), (7, 6), (8, 3)]
[(1, 1), (2, 7), (3, 5), (4, 8), (5, 2), (6, 4), (7, 6), (8, 3)]
[(1, 2), (2, 5), (3, 7), (4, 4), (5, 1), (6, 8), (7, 6), (8, 3)]
[(1, 4), (2, 2), (3, 7), (4, 5), (5, 1), (6, 8), (7, 6), (8, 3)]
[(1, 5), (2, 7), (3, 1), (4, 4), (5, 2), (6, 8), (7, 6), (8, 3)]
[(1, 6), (2, 4), (3, 1), (4, 5), (5, 8), (6, 2), (7, 7), (8, 3)]
[(1, 5), (2, 1), (3, 4), (4, 6), (5, 8), (6, 2), (7, 7), (8, 3)]
[(1, 5), (2, 2), (3, 6), (4, 1), (5, 7), (6, 4), (7, 8), (8, 3)]
[(1, 6), (2, 3), (3, 7), (4, 2), (5, 8), (6, 5), (7, 1), (8, 4)]
[(1, 2), (2, 7), (3, 3), (4, 6), (5, 8), (6, 5), (7, 1), (8, 4)]
[(1, 7), (2, 3), (3, 1), (4, 6), (5, 8), (6, 5), (7, 2), (8, 4)]
[(1, 5), (2, 1), (3, 8), (4, 6), (5, 3), (6, 7), (7, 2), (8, 4)]
[(1, 1), (2, 5), (3, 8), (4, 6), (5, 3), (6, 7), (7, 2), (8, 4)]
[(1, 3), (2, 6), (3, 8), (4, 1), (5, 5), (6, 7), (7, 2), (8, 4)]
[(1, 6), (2, 3), (3, 1), (4, 7), (5, 5), (6, 8), (7, 2), (8, 4)]
[(1, 7), (2, 5), (3, 3), (4, 1), (5, 6), (6, 8), (7, 2), (8, 4)]
[(1, 7), (2, 3), (3, 8), (4, 2), (5, 5), (6, 1), (7, 6), (8, 4)]
[(1, 5), (2, 3), (3, 1), (4, 7), (5, 2), (6, 8), (7, 6), (8, 4)]
[(1, 2), (2, 5), (3, 7), (4, 1), (5, 3), (6, 8), (7, 6), (8, 4)]
[(1, 3), (2, 6), (3, 2), (4, 5), (5, 8), (6, 1), (7, 7), (8, 4)]
[(1, 6), (2, 1), (3, 5), (4, 2), (5, 8), (6, 3), (7, 7), (8, 4)]
[(1, 8), (2, 3), (3, 1), (4, 6), (5, 2), (6, 5), (7, 7), (8, 4)]
[(1, 2), (2, 8), (3, 6), (4, 1), (5, 3), (6, 5), (7, 7), (8, 4)]
[(1, 5), (2, 7), (3, 2), (4, 6), (5, 3), (6, 1), (7, 8), (8, 4)]
[(1, 3), (2, 6), (3, 2), (4, 7), (5, 5), (6, 1), (7, 8), (8, 4)]
[(1, 6), (2, 2), (3, 7), (4, 1), (5, 3), (6, 5), (7, 8), (8, 4)]
[(1, 3), (2, 7), (3, 2), (4, 8), (5, 6), (6, 4), (7, 1), (8, 5)]
[(1, 6), (2, 3), (3, 7), (4, 2), (5, 4), (6, 8), (7, 1), (8, 5)]
[(1, 4), (2, 2), (3, 7), (4, 3), (5, 6), (6, 8), (7, 1), (8, 5)]
[(1, 7), (2, 1), (3, 3), (4, 8), (5, 6), (6, 4), (7, 2), (8, 5)]
[(1, 1), (2, 6), (3, 8), (4, 3), (5, 7), (6, 4), (7, 2), (8, 5)]
[(1, 3), (2, 8), (3, 4), (4, 7), (5, 1), (6, 6), (7, 2), (8, 5)]
[(1, 6), (2, 3), (3, 7), (4, 4), (5, 1), (6, 8), (7, 2), (8, 5)]
[(1, 7), (2, 4), (3, 2), (4, 8), (5, 6), (6, 1), (7, 3), (8, 5)]
[(1, 4), (2, 6), (3, 8), (4, 2), (5, 7), (6, 1), (7, 3), (8, 5)]
[(1, 2), (2, 6), (3, 1), (4, 7), (5, 4), (6, 8), (7, 3), (8, 5)]
[(1, 2), (2, 4), (3, 6), (4, 8), (5, 3), (6, 1), (7, 7), (8, 5)]
[(1, 3), (2, 6), (3, 8), (4, 2), (5, 4), (6, 1), (7, 7), (8, 5)]
[(1, 6), (2, 3), (3, 1), (4, 8), (5, 4), (6, 2), (7, 7), (8, 5)]
[(1, 8), (2, 4), (3, 1), (4, 3), (5, 6), (6, 2), (7, 7), (8, 5)]
[(1, 4), (2, 8), (3, 1), (4, 3), (5, 6), (6, 2), (7, 7), (8, 5)]
[(1, 2), (2, 6), (3, 8), (4, 3), (5, 1), (6, 4), (7, 7), (8, 5)]
[(1, 7), (2, 2), (3, 6), (4, 3), (5, 1), (6, 4), (7, 8), (8, 5)]
[(1, 3), (2, 6), (3, 2), (4, 7), (5, 1), (6, 4), (7, 8), (8, 5)]
[(1, 4), (2, 7), (3, 3), (4, 8), (5, 2), (6, 5), (7, 1), (8, 6)]
[(1, 4), (2, 8), (3, 5), (4, 3), (5, 1), (6, 7), (7, 2), (8, 6)]
[(1, 3), (2, 5), (3, 8), (4, 4), (5, 1), (6, 7), (7, 2), (8, 6)]
[(1, 4), (2, 2), (3, 8), (4, 5), (5, 7), (6, 1), (7, 3), (8, 6)]
[(1, 5), (2, 7), (3, 2), (4, 4), (5, 8), (6, 1), (7, 3), (8, 6)]
[(1, 7), (2, 4), (3, 2), (4, 5), (5, 8), (6, 1), (7, 3), (8, 6)]
[(1, 8), (2, 2), (3, 4), (4, 1), (5, 7), (6, 5), (7, 3), (8, 6)]
[(1, 7), (2, 2), (3, 4), (4, 1), (5, 8), (6, 5), (7, 3), (8, 6)]
[(1, 5), (2, 1), (3, 8), (4, 4), (5, 2), (6, 7), (7, 3), (8, 6)]
[(1, 4), (2, 1), (3, 5), (4, 8), (5, 2), (6, 7), (7, 3), (8, 6)]
[(1, 5), (2, 2), (3, 8), (4, 1), (5, 4), (6, 7), (7, 3), (8, 6)]
[(1, 3), (2, 7), (3, 2), (4, 8), (5, 5), (6, 1), (7, 4), (8, 6)]
[(1, 3), (2, 1), (3, 7), (4, 5), (5, 8), (6, 2), (7, 4), (8, 6)]
[(1, 8), (2, 2), (3, 5), (4, 3), (5, 1), (6, 7), (7, 4), (8, 6)]
[(1, 3), (2, 5), (3, 2), (4, 8), (5, 1), (6, 7), (7, 4), (8, 6)]
[(1, 3), (2, 5), (3, 7), (4, 1), (5, 4), (6, 2), (7, 8), (8, 6)]
[(1, 5), (2, 2), (3, 4), (4, 6), (5, 8), (6, 3), (7, 1), (8, 7)]
[(1, 6), (2, 3), (3, 5), (4, 8), (5, 1), (6, 4), (7, 2), (8, 7)]
[(1, 5), (2, 8), (3, 4), (4, 1), (5, 3), (6, 6), (7, 2), (8, 7)]
[(1, 4), (2, 2), (3, 5), (4, 8), (5, 6), (6, 1), (7, 3), (8, 7)]
[(1, 4), (2, 6), (3, 1), (4, 5), (5, 2), (6, 8), (7, 3), (8, 7)]
[(1, 6), (2, 3), (3, 1), (4, 8), (5, 5), (6, 2), (7, 4), (8, 7)]
[(1, 5), (2, 3), (3, 1), (4, 6), (5, 8), (6, 2), (7, 4), (8, 7)]
[(1, 4), (2, 2), (3, 8), (4, 6), (5, 1), (6, 3), (7, 5), (8, 7)]
[(1, 6), (2, 3), (3, 5), (4, 7), (5, 1), (6, 4), (7, 2), (8, 8)]
[(1, 6), (2, 4), (3, 7), (4, 1), (5, 3), (6, 5), (7, 2), (8, 8)]
[(1, 4), (2, 7), (3, 5), (4, 2), (5, 6), (6, 1), (7, 3), (8, 8)]
[(1, 5), (2, 7), (3, 2), (4, 6), (5, 3), (6, 1), (7, 4), (8, 8)]

Process finished with exit code 0

20 lines : Prime numbers (质数/素数) sieve (筛) w/fancy generators (发生器)

#import迭代器
import itertools

def iter_primes():
    # an iterator of all numbers between 2 and + infinity
    numbers = itertools.count(2)

    # generate primes forever
    while True:
        # get the first number from the iterator (always a prime)
        prime = next(numbers)
        yield prime

        numbers = filter(prime.__rmod__,numbers)

for p in iter_primes():
    if p > 1000:
        break
    print(p)

21 lines : XML/HTML parsing (using Python 2.5 or third-party library)

dinner_recipe = '''<html><body><table>
<tr><th>amt</th><th>unit</th><th>item</th></tr>
<tr><td>24</td><td>slices</td><td>baguette</td></tr>
<tr><td>2+</td><td>tbsp</td><td>olive oil</td></tr>
<tr><td>1</td><td>cup</td><td>tomatoes</td></tr>
<tr><td>1</td><td>jar</td><td>pesto</td></tr>
</table></body></html>'''

# In Python 2.5 or from http://effbot.org/zone/element-index.htm
import xml.etree.ElementTree as etree
tree = etree.fromstring(dinner_recipe)

# For invalid HTML use http://effbot.org/zone/element-soup.htm
# import ElementSoup, StringIO
# tree = ElementSoup.parse(StringIO.StringIO(dinner_recipe))

pantry = set(['olive oil', 'pesto'])
for ingredient in tree.getiterator('tr'):    ukzq: for 参数 in 集合:
    amt, unit, item = ingredient
    if item.tag == "td" and item.text not in pantry:
        print("%s: %s %s" % (item.text, amt.text, unit.text))

28 lines : 8-Queens Problem (define your own exceptions) (8皇后问题,定义你自己的异常类)

BOARD_SIZE = 8

class BailOut(Exception):
    pass

def validate(queens):
    left = right = col = queens[-1]
    for r in reversed(queens[:-1]):
        left, right = left-1, right+1
        if r in (left,col,right):
            raise BailOut

def add_queen(queens):
    for i in range(BOARD_SIZE):
        test_queens = queens + [i]
        try:
            validate(test_queens)
            if len(test_queens) == BOARD_SIZE:
                return test_queens
            else:
                return add_queen(test_queens)
        except BailOut:
            pass
    raise BailOut

queens = add_queen([])
print(queens)
print(("\n".join(". "*q + "Q " + ". "*(BOARD_SIZE-q-1) for q in queens)))

33 lines : “Guess the Number” Game (edited) from http://inventwithpython.com

import random

guesses_made = 0

name = input('Hello! What is your name?\n')

number = random.randint(1,20)
print(('Well, {0}, I am thinking of a number between 1 and 20.'.format(name)))

while guesses_made < 6:

    guess = int(input('Take a guess: '))

    guesses_made += 1

    if guess < number:
        print ('Your guess is too low.')

    if guess > number:
        print ('Your guess is too high.')

    if guess == number:
        break

if guess == number:
    print('Good job, {0}! You guessed my number in {1} guesses!'.format(name,guesses_made))
else:
    print('Nope. The number I was thinking of was {0}'.format(number))

abstract base class – 抽象基类
抽象基类简称 ABC，是对 duck-typing 的补充，它提供了一种定义接口的新方式，相比之下其他技巧例如 hasattr() 显得过于笨拙或有微妙错误（例如使用魔术方法）。ABC 引入了虚拟子类，这种类并非继承自其他类，但却仍能被 isinstance() 和 issubclass() 所认可；详见 abc 模块文档。Python 自带许多内置的 ABC 用于实现数据结构（在 collections.abc 模块中）、数字（在 numbers 模块中）、流（在 io 模块中）、导入查找器和加载器（在 importlib.abc 模块中）。你可以使用 abc 模块来创建自己的 ABC。

annotation – 标注
关联到某个变量、类属性、函数形参或返回值的标签，被约定作为 type hint 来使用。
局部变量的标注在运行时不可访问，但全局变量、类属性和函数的标注会分别存放模块、类和函数的 annotations 特殊属性中。
参见 variable annotation、function annotation、PEP 484 和 PEP 526，对此功能均有介绍。

argument – 参数
在调用函数时传给 function (或method) 的值, 参数分为两种:

关键字参数: 在函数调用中前面带有标识符 (例如 name=) 或者作为包含在前面带有 ** 的字典里的值传入. 举例来说, 3和5在以下对 complex() 的调用中均属于关键字参数:

complex(real=3, imag=5)
complex(**{'real':3,'imag':5})

位置参数: 不属于关键字参数的参数. 位置参数可出现于参数列表的开头以及/或者作为前面带有 * 的iterable里的元素被传入. 举例来说, 3和5在以下调用中均属于位置参数:

complex(3,5)
complex(*(3,5))

参数会被赋值给函数体中对应的局部变量。有关赋值规则参见调用一节。根据语法，任何表达式都可用来表示一个参数；最终算出的值会被赋给对应的局部变量。
另参见 parameter 术语表条目，常见问题中参数与形参的区别以及 PEP 362。

码农公寓

python入门及进阶学习记 lesson1

相关文章