Python：Python学习总结详解编程语言

1 # coding=utf-8 
2  
3 print "你好，世界。"

1 print 2**10

1 var = 1 
2 print var 
3  
4 var  = "段光伟" 
5 print var

1 #获取用户输入 
2 x = input("x:") 
3 y = input("y:") 
4  
5 print x*y

1 def say_b(): 
2     print "b"

1 #1 + “1” 这行代码在Python中会报错。 
2 print 1 + int("1") 
3 print str(1) + "1"

1 #字符串 
2 print ''''    段 
3             光 
4             伟''' 
5 print r'C:/log.txt' 
6 print 'C://log.txt'

 1 seq = "0123456789" 
 2 print seq[0] #从0开始编码。 
 3 print seq[-1] #支持倒着数数，-1代表倒数第一。 
 4 print seq[1:5] #支持分片操作，seq[start:end]，start会包含在结果中，end不会包含在结果中。 
 5 print seq[7:] #seq[start:end]中的end可以省略。 
 6 print seq[-3:] #分片也支持负数。 
 7 print seq[:3] #seq[start:end]中的start也可以省略。 
 8 print seq[:] #全部省略会复制整个序列。 
 9 print seq[::2] #支持步长。 
10 print seq[::-2] #支持负步长。 
11 print seq[9:1:-1] #支持负步长。 
12 print [1, 2, 3] + [4, 5, 6] # 序列支持相加，这解释了为啥字符串可以相加。 
13 print [1, 2, 3] * 3 #序列支持相乘，这解释了为啥字符串可以相称。 
14 print [None] * 10 #生成一个空序列。 
15 print 1 in [1, 2, 3] #成员判断。

 1 data = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; 
 2  
 3 data[0] = "a" #修改元素。 
 4 print data 
 5 data[0] = 0 
 6  
 7 del data[10] #删除元素。 
 8 print data 
 9  
10 del data[8:] #分片删除。 
11 print data 
12  
13 data[8:] = [8, 9, 10] #分片赋值 
14 print data

1 print (1, 2) #元祖以小括号形式声明。 
2 print (1,) #一个元素的元祖。

1 print "% 10s" % "----" 
2  
3 print ''' 
4 %(title)s 
5 %(body)s 
6 ''' % {"title": "标题", "body": "内容"}

1 print {"title": "title", "body": "body"} 
2 print dict(title = "title", body = "body") 
3 print dict([("title", "title"), ("body", "body")])

1 dic = {"title": "title", "body": "body"}; 
2 print dic["title"] 
3 del dic["title"] 
4 print dic

1 print 'a', 'b' #print可以接受多个参数，参数的输出之间以空格相隔。 
2 print 'a', #如果逗号之后没有参数，则不会换行。 
3 print 'b'

1 x, y, z = 1, 2, 3 
2 print x, y, z 
3 (x, y, z) = (1, 2, 3) 
4 print x, y, z 
5 (x, y, z) = [1, 2, 3] 
6 print x, y, z

 1 #下面的输入全部返回False。 
 2 print(bool(None)) 
 3 print(bool(())) 
 4 print(bool([])) 
 5 print(bool({})) 
 6 print(bool("")) 
 7 print(bool(0)) 
 8  
 9 #虽然这些值在条件运算中会当做False，但是本身不等于False。 
10 print(True and "") 
11 print(not "") 
12 print(False == "") 
13 print(False == 0) #0除外，bool类型的内部表示就是int类型。

1 print(0 < 1 < 10) 
2 print(0 < 1 and 1 < 10) 
3 print(not(0 > 1 > 10)) 
4 print(not(0 > 1 or 1 > 10))

1 if(10 > 1): 
2     print("10 > 1") 
3 else: 
4     print("不可能发生")

1 print("10 > 1" if 10 > 1 else "不可能发生")

1 #== 和 is的差别，==比较的是内容，is比较的是引用。 
2 x = [1, 2, 3] 
3 y = x 
4 z = [1, 2, 3] 
5 print(x == y) 
6 print(x == z) 
7 print(x is y) 
8 print(x is z)

 1 #for循环类似C#的foreach，注意for后面是没有括号的，python真是能简洁就尽量简洁。 
 2 for x in range(1, 10): 
 3     print(x) 
 4  
 5 for key in {"x":"xxx"}: 
 6     print(key) 
 7  
 8 for key, value in {"x":"xxx"}.items(): 
 9     print(key, value) 
10  
11 for x, y, z in [["a", 1, "A"],["b", 2, "B"]]: 
12     print(x, y, z)

 1 #带索引的遍历 
 2 for index, value in enumerate(range(0, 10)): 
 3     print(index, value) 
 4  
 5 #好用的zip方法 
 6 for x, y in zip(range(1, 10), range(1, 10)): 
 7     print(x, y) 
 8  
 9 #循环中的的else子句 
10 from math import sqrt 
11 for item in range(99, 1, -1): 
12     root = sqrt(item) 
13     if(root == int(root)): 
14         print(item) 
15         break 
16 else: 
17     print("没有执行break语句。")

1 #pass、exec、eval 
2 if(1 == 1): 
3     pass 
4  
5 exec('print(x)', {"x": "abc"}) 
6 print(eval('x*2', {"x": 5}))

 1 # 基本函数定义。 
 2 def func(): 
 3     print("func") 
 4  
 5 func() 
 6  
 7 # 带返回值的函数。 
 8 def func_with_return(): 
 9     return ("func_with_return") 
10  
11 print(func_with_return()) 
12  
13 # 带多个返回值的函数。 
14 def func_with_muti_return(): 
15     return ("func_with_muti_return", "func_with_muti_return") 
16  
17 print(func_with_muti_return()) 
18  
19 # 位置参数 
20 def func_with_parameters(x, y): 
21     print(x, y) 
22  
23 func_with_parameters(1, 2) 
24  
25 # 收集多余的位置参数 
26 def func_with_collection_rest_parameters(x, y, *rest): 
27     print(x, y) 
28     print(rest) 
29  
30 func_with_collection_rest_parameters(1, 2, 3, 4, 5) 
31  
32 #命名参数 
33 def func_with_named_parameters(x, y, z): 
34     print(x, y, z) 
35  
36 func_with_named_parameters(z = 1, y = 2, x = 3) 
37  
38 #默认值参数 
39 def func_with_default_value_parameters(x, y, z = 3): 
40     print(x, y, z) 
41  
42 func_with_default_value_parameters(y = 2, x = 1) 
43  
44 #收集命名参数 
45 def func_with_collection_rest_naned_parameters(*args, **named_agrs): 
46     print(args) 
47     print(named_agrs) 
48  
49 func_with_collection_rest_naned_parameters(1, 2, 3, x = 4, y = 5, z = 6) 
50  
51 #集合扁平化 
52 func_with_collection_rest_naned_parameters([1, 2, 3], {"x": 4, "y": 4, "z": 6}) #这会导致args[0]指向第一个实参，args[1]指向第二个实参。 
53 func_with_collection_rest_naned_parameters(*[1, 2, 3], **{"x": 4, "y": 4, "z": 6}) #这里的执行相当于func_with_collection_rest_naned_parameters(1, 2, 3, x = 4, y = 5, z = 6)。

 1 # coding=utf-8 
 2  
 3 # 只有函数执行才会开启一个作用域。 
 4 if(2 > 1): 
 5     x = 1 
 6  
 7 print(x) # 会输出1。 
 8  
 9  
10 # 使用vars()函数可以访问当前作用域包含的变量。 
11 x = 1 
12 print(vars()["x"]) 
13  
14 # 使用globals()函数可以访问全局作用域。 
15 x = 1 
16  
17 def func(): 
18     print(globals()["x"]) 
19  
20 func() 
21  
22 # 使用locals()函数可以访问局部作用域。 
23 def func(): 
24     x = 2 
25     print(locals()["x"]) 
26  
27 func() 
28  
29 # 每个函数定义时都会记住所在的作用域。 
30 # 函数执行的时候会开启一个新的作用域，函数内变量访问的规则是：先访问当前作用域，如果没有就访问函数定义时的作用域，递归直到全局作用域。 
31 x = 1 
32  
33 def func(): 
34     y = 2 
35     print(x, y) # 输出1 2 
36  
37 func() 
38  
39  
40 # 变量赋值始终访问的是当前作用域。 
41 x = 1 
42  
43 def func(): 
44     x = 2 
45     y = 2 
46     print(x, y) # 输出2 2 
47  
48 func() 
49 print(x) #输出 1 
50  
51 # 局部变量会覆盖隐藏全局变量，想访问全局变量可以采用global关键字或globals()函数。 
52 x = 1 
53  
54 def func(): 
55     global x 
56     x = 2 
57     y = 2 
58     print(x, y) # 输出2 2 
59  
60 func() 
61 print(x) #输出 2

 1 # python支持闭包 
 2 def func(x): 
 3     def inner_func(y): 
 4         print(x + y) 
 5  
 6     return inner_func 
 7  
 8 inner_func = func(10) 
 9 inner_func(1) 
10 inner_func(2)

1 #函数作为对象 
2 def func(fn, arg): 
3     fn(arg) 
4  
5 func(print, "hello") 
6 func(lambda arg : print(arg), "hello")

1 # coding=utf-8 
2  
3 print __name__ 
4  
5 def say_b(): 
6     print "b"

1 # coding=utf-8 
2  
3 import b 
4 from b import * 
5  
6 print __name__ 
7  
8 def say_a(): 
9     print "a"

1 # coding=utf-8 
2  
3 import a 
4  
5 print __name__ 
6  
7 a.say_a(); 
8 a.say_b(); 
9 a.b.say_b()

1 b 
2 a 
3 __main__ 
4 a 
5 b 
6 b

 1 # coding=utf-8 
 2  
 3 # 自定义异常 
 4 class HappyException(Exception): 
 5     pass 
 6  
 7 # 引发和捕获异常 
 8 try: 
 9     raise HappyException 
10 except: 
11     print("HappyException") 
12  
13 try: 
14     raise HappyException() 
15 except: 
16     print("HappyException") 
17  
18 # 捕获多种异常 
19 try: 
20     raise HappyException 
21 except (HappyException, TypeError): 
22     print("HappyException") 
23  
24 # 重新引发异常 
25 try: 
26     try: 
27         raise HappyException 
28     except (HappyException, TypeError): 
29         raise 
30 except: 
31     print("HappyException") 
32  
33 #访问异常实例 
34 try: 
35     raise HappyException("都是我的错") 
36 except (HappyException, TypeError), e: 
37     print(e) 
38  
39 #按类型捕获 
40 try: 
41     raise HappyException 
42 except HappyException: 
43     print("HappyException") 
44 except TypeError: 
45     print("TypeError") 
46  
47 #全面捕获 
48 try: 
49     raise HappyException 
50 except: 
51     print("HappyException") 
52  
53 #没有异常的else 
54 try: 
55     pass 
56 except: 
57     print("HappyException") 
58 else: 
59     print("没有异常") 
60  
61 #总会执行的final 
62 try: 
63     pass 
64 except: 
65     print("HappyException") 
66 else: 
67     print("没有异常") 
68 finally: 
69     print("总会执行")

 1 # coding=utf-8 
 2  
 3 __metaclass__ = type 
 4  
 5 # 类型定义 
 6 # 实例方法必的第一个参数代表类型实例，类似其他语言的this。 
 7 class Animal: 
 8     name = "未知" # 属性定义。 
 9  
10     def __init__(self, name): #构造方法定义。 
11         self.name = name 
12  
13     def getName(self): # 实例方法定义。 
14         return self.name 
15  
16     def setName(self, value): 
17         self.name = value 
18  
19 print(Animal.name) # 未知 
20 print(Animal.__dict__["name"]) # 未知 
21  
22 animal = Animal("狗狗") 
23 print(animal.name) # 狗狗 
24 print(animal.__dict__["name"]) # 狗狗 
25 print(Animal.name) # 未知 
26 print(Animal.__dict__["name"]) # 未知 
27 print(animal.__class__.name) # 未知 
28 print(animal.__class__.__dict__["name"]) # 未知

1 # 类型定义中的代码会执行，是一个独立的作用域。 
2 class TestClass: 
3     print("类型定义中") #类型定义中

 1 class TestClass: 
 2     def method(self): 
 3         print("测试方法") 
 4  
 5 test = TestClass() 
 6 print(TestClass.method) #<unbound method TestClass.method> 
 7 print(test.method) #<bound method TestClass.method of <__main__.TestClass object at 0x021B46D0>> 
 8  
 9 TestClass.method(test) #测试方法 
10 test.method() #测试方法

1 # 私有成员 
2 class TestClass: 
3     __private_property = 1 
4  
5     def __private_method(): 
6         pass 
7  
8 print(TestClass.__dict__) # {'__module__': '__main__', '_TestClass__private_method': <function __private_method at 0x0212B970>, '_TestClass__private_property': 1

 1 #多重继承 
 2 class Base1: 
 3     pass 
 4  
 5 class Base2: 
 6     pass 
 7  
 8 class Child(Base2, Base1): 
 9     pass 
10  
11 child = Child() 
12 print(isinstance(child, Child)) # True 
13 print(isinstance(child, Base2)) # True 
14 print(isinstance(child, Base1)) # True

 1 class TestClass1: 
 2     def say(self): 
 3         print("我是鸭子1") 
 4  
 5 class TestClass2: 
 6     def say(self): 
 7         print("我是鸭子2") 
 8  
 9 def duck_say(duck): 
10     duck.say() 
11  
12 duck_say(TestClass1()) # 我是鸭子1 
13 duck_say(TestClass2()) # 我是鸭子2

 1 # 调用父类 
 2 class Base: 
 3     def say(self): 
 4         print("Base") 
 5  
 6 class Child(Base): 
 7     def say(self): 
 8         Base.say(self) 
 9         super(Child, self).say() 
10         print("Child") 
11  
12 child = Child() 
13 child.say()

 1 from os.path import join 
 2  
 3 class FileObject: 
 4     '''Wrapper for file objects to make sure the file gets closed on deletion.''' 
 5  
 6     def __init__(self, filepath='~', filename='sample.txt'): 
 7         # open a file filename in filepath in read and write mode 
 8         self.file = open(join(filepath, filename), 'r+') 
 9  
10     def __del__(self): 
11         self.file.close() 
12         del self.file

 1 class Word(str): 
 2     '''Class for words, defining comparison based on word length.''' 
 3  
 4     def __new__(cls, word): 
 5         # Note that we have to use __new__. This is because str is an immutable 
 6         # type, so we have to initialize it early (at creation) 
 7         if ' ' in word: 
 8             print "Value contains spaces. Truncating to first space." 
 9             word = word[:word.index(' ')] # Word is now all chars before first space 
10         return str.__new__(cls, word) 
11  
12     def __gt__(self, other): 
13         return len(self) > len(other) 
14  
15     def __lt__(self, other): 
16         return len(self) < len(other) 
17  
18     def __ge__(self, other): 
19         return len(self) >= len(other) 
20  
21     def __le__(self, other): 
22         return len(self) <= len(other) 
23  
24 print(Word("duan") > Word("wei"))

 1 class AccessCounter: 
 2     '''A class that contains a value and implements an access counter. 
 3     The counter increments each time the value is changed.''' 
 4  
 5     def __init__(self, value): 
 6         super(AccessCounter, self).__setattr__('counter', 0) 
 7         super(AccessCounter, self).__setattr__('value', value) 
 8  
 9     def __setattr__(self, name, value): 
10         if name == 'value': 
11             super(AccessCounter, self).__setattr__('counter', self.counter + 1) 
12         # Make this unconditional. 
13         # If you want to prevent other attributes to be set, raise AttributeError(name) 
14         super(AccessCounter, self).__setattr__(name, value) 
15  
16     def __delattr__(self, name): 
17         if name == 'value': 
18             super(AccessCounter, self).__setattr__('counter', self.counter + 1) 
19         super(AccessCounter, self).__delattr__(name)

 1 class FunctionalList: 
 2     '''A class wrapping a list with some extra functional magic, like head, 
 3     tail, init, last, drop, and take.''' 
 4  
 5     def __init__(self, values=None): 
 6         if values is None: 
 7             self.values = [] 
 8         else: 
 9             self.values = values 
10  
11     def __len__(self): 
12         return len(self.values) 
13  
14     def __getitem__(self, key): 
15         # if key is of invalid type or value, the list values will raise the error 
16         return self.values[key] 
17  
18     def __setitem__(self, key, value): 
19         self.values[key] = value 
20  
21     def __delitem__(self, key): 
22         del self.values[key] 
23  
24     def __iter__(self): 
25         return iter(self.values) 
26  
27     def __reversed__(self): 
28         return FunctionalList(reversed(self.values)) 
29  
30     def append(self, value): 
31         self.values.append(value) 
32     def head(self): 
33         # get the first element 
34         return self.values[0] 
35     def tail(self): 
36         # get all elements after the first 
37         return self.values[1:] 
38     def init(self): 
39         # get elements up to the last 
40         return self.values[:-1] 
41     def last(self): 
42         # get last element 
43         return self.values[-1] 
44     def drop(self, n): 
45         # get all elements except first n 
46         return self.values[n:] 
47     def take(self, n): 
48         # get first n elements 
49         return self.values[:n]

 1 class Entity: 
 2     '''Class to represent an entity. Callable to update the entity's position.''' 
 3  
 4     def __init__(self, size, x, y): 
 5         self.x, self.y = x, y 
 6         self.size = size 
 7  
 8     def __call__(self, x, y): 
 9         '''Change the position of the entity.''' 
10         self.x, self.y = x, y 
11         print(x, y) 
12  
13 entity = Entity(5, 1, 1) 
14 entity(2, 2)

 1 class Closer: 
 2     def __enter__(self): 
 3         return self 
 4  
 5     def __exit__(self, exception_type, exception_val, trace): 
 6         print("清理完成") 
 7         return True; 
 8  
 9 with Closer() as closer: 
10     pass

 1 class Meter(object): 
 2     '''Descriptor for a meter.''' 
 3  
 4     def __init__(self, value=0.0): 
 5         self.value = float(value) 
 6     def __get__(self, instance, owner): 
 7         return self.value 
 8     def __set__(self, instance, value): 
 9         self.value = float(value) 
10  
11 class Foot(object): 
12     '''Descriptor for a foot.''' 
13  
14     def __get__(self, instance, owner): 
15         return instance.meter * 3.2808 
16     def __set__(self, instance, value): 
17         instance.meter = float(value) / 3.2808 
18  
19 class Distance(object): 
20     '''Class to represent distance holding two descriptors for feet and 
21     meters.''' 
22     meter = Meter() 
23     foot = Foot()

1 # coding=utf-8 
2  
3 def paly(self): 
4     print("游戏中...")

1 # coding=utf-8 
2  
3 class Animal: 
4     from playable import paly 
5  
6 animal = Animal() 
7 animal.paly() # 游戏中...

 1 #coding:utf-8 
 2  
 3 class TestClass: 
 4     def method1(self): 
 5         print("方法1") 
 6  
 7 def method2(self): 
 8     print("方法2") 
 9  
10 TestClass.method2 = method2 
11  
12 test = TestClass() 
13 test.method1() # 方法1 
14 test.method2() # 方法2

1 TestClass = type("TestClass", (object,), { 
2     "say": lambda self : print("你好啊") 
3 }) 
4  
5 test = TestClass() 
6 test.say()

 1 def getter(name): 
 2     def getterMethod(self): 
 3         return self.__getattribute__(name) 
 4     return getterMethod 
 5  
 6 def setter(name): 
 7     def setterMethod(self, value): 
 8         self.__setattr__(name, value) 
 9     return setterMethod     
10  
11 class TestClass: 
12     getName = getter("name") 
13     setName = setter("name") 
14  
15 test = TestClass() 
16 test.setName("段光伟") 
17 print(test.getName())