PythonS12-day4學習筆記

# 迭代器、裝飾器、生成器
# 迭代器
li = [1, 3, 'he', '&']
n = iter(li)
print(n.__next__())
import os, sys


# 生成器
def func():
    for i in xrange(10):
        yield (i)
        print(i)

  1 # 裝飾器
  2 #使用裝飾函數在函數執行前和執行後分別附加額外功能
  3 '''示例2: 替換函數(裝飾)
  4 裝飾函數的參數是被裝飾的函數對象，返回原函數對象
  5 裝飾的實質語句: myfunc = deco(myfunc)'''
  6 def deco(func):
  7     print("before myfunc() called.")
  8     func()
  9     print("  after myfunc() called.")
 10     return func
 11 def myfunc():
 12     print(" myfunc() called.")
 13 myfunc = deco(myfunc)
 14 myfunc()
 15 myfunc()
 16 #使用語法糖@來裝飾函數
 17 '''示例3: 使用語法糖@來裝飾函數，至關於「myfunc = deco(myfunc)」
 18 但發現新函數只在第一次被調用，且原函數多調用了一次'''
 19 def deco(func):
 20     print("before myfunc() called.")
 21     func()
 22     print("  after myfunc() called.")
 23     return func
 24 @deco
 25 def myfunc():
 26     print(" myfunc() called.")
 27 myfunc()
 28 myfunc()
 29 
 30 #用內嵌包裝函數來確保每次新函數都被調用
 31 def deco(func):
 32     def _deco():
 33         print("before myfunc() called.")
 34         func()
 35         print("  after myfunc() called.")
 36         # 不須要返回func，實際上應返回原函數的返回值
 37     return _deco
 38 @deco
 39 def myfunc():
 40     print(" myfunc() called.")
 41     return 'ok'
 42 myfunc()
 43 myfunc()
 44 #對帶參數的函數進行裝飾
 45 def deco(func):
 46     def _deco(a, b):
 47         print("before myfunc() called.")
 48         ret = func(a, b)
 49         print("  after myfunc() called. result: %s" % ret)
 50         return ret
 51     return _deco
 52 @deco
 53 def myfunc(a, b):
 54     print(" myfunc(%s,%s) called." % (a, b))
 55     return a + b
 56 myfunc(1, 2)
 57 myfunc(3, 4)
 58 #對參數數量不肯定的函數進行裝飾
 59 '''示例6: 對參數數量不肯定的函數進行裝飾，
 60 參數用(*args, **kwargs)，自動適應變參和命名參數'''
 61 def deco(func):
 62     def _deco(*args, **kwargs):
 63         print("before %s called." % func.__name__)
 64         ret = func(*args, **kwargs)
 65         print("  after %s called. result: %s" % (func.__name__, ret))
 66         return ret
 67     return _deco
 68 @deco
 69 def myfunc(a, b):
 70     print(" myfunc(%s,%s) called." % (a, b))
 71     return a+b
 72 @deco
 73 def myfunc2(a, b, c):
 74     print(" myfunc2(%s,%s,%s) called." % (a, b, c))
 75     return a+b+c
 76 myfunc(1, 2)
 77 myfunc(3, 4)
 78 myfunc2(1, 2, 3)
 79 myfunc2(3, 4, 5)
 80 
 81 #讓裝飾器帶參數
 82 def deco(arg):
 83     def _deco(func):
 84         def __deco():
 85             print("before %s called [%s]." % (func.__name__, arg))
 86             func()
 87             print("  after %s called [%s]." % (func.__name__, arg))
 88         return __deco
 89     return _deco
 90 
 91 @deco("mymodule")
 92 def myfunc():
 93     print(" myfunc() called.")
 94 
 95 @deco("module2")
 96 
 97 def myfunc2():
 98     print(" myfunc2() called.")
 99 myfunc()
100 myfunc2()
101 #讓裝飾器帶 類 參數
102 '''示例8: 裝飾器帶類參數'''
103 class locker:
104     def __init__(self):
105         print("locker.__init__() should be not called.")
106     @staticmethod
107     def acquire():
108         print("locker.acquire() called.（這是靜態方法）")
109     @staticmethod
110     def release():
111         print("  locker.release() called.（不須要對象實例）")
112 def deco(cls):
113     '''cls 必須實現acquire和release靜態方法'''
114     def _deco(func):
115         def __deco():
116             print("before %s called [%s]." % (func.__name__, cls))
117             cls.acquire()
118             try:
119                 return func()
120             finally:
121                 cls.release()
122         return __deco
123     return _deco
124 @deco(locker)
125 def myfunc():
126     print(" myfunc() called.")
127 myfunc()
128 myfunc()
129 #裝飾器帶類參數，並分拆公共類到其餘py文件中，同時演示了對一個函數應用多個裝飾器
130 '''mylocker.py: 公共類 for 示例9.py'''
131 class mylocker:
132     def __init__(self):
133         print("mylocker.__init__() called.")
134     @staticmethod
135     def acquire():
136         print("mylocker.acquire() called.")
137     @staticmethod
138     def unlock():
139         print("  mylocker.unlock() called.")
140 class lockerex(mylocker):
141     @staticmethod
142     def acquire():
143         print("lockerex.acquire() called.")
144     @staticmethod
145     def unlock():
146         print("  lockerex.unlock() called.")
147 def lockhelper(cls):
148     '''cls 必須實現acquire和release靜態方法'''
149     def _deco(func):
150         def __deco(*args, **kwargs):
151             print("before %s called." % func.__name__)
152             cls.acquire()
153             try:
154                 return func(*args, **kwargs)
155             finally:
156                 cls.unlock()
157         return __deco
158     return _deco
159 '''示例9: 裝飾器帶類參數，並分拆公共類到其餘py文件中
160 同時演示了對一個函數應用多個裝飾器'''
161 from mylocker import *
162 class example:
163     @lockhelper(mylocker)
164     def myfunc(self):
165         print(" myfunc() called.")
166     @lockhelper(mylocker)
167     @lockhelper(lockerex)
168     def myfunc2(self, a, b):
169         print(" myfunc2() called.")
170         return a + b
171 if __name__=="__main__":
172     a = example()
173     a.myfunc()
174     print(a.myfunc())
175     print(a.myfunc2(1, 2))
176     print(a.myfunc2(3, 4))

 1 # 遞歸
 2 #斐波那契數列
 3 def func(arg1, arg2, stop):
 4     if arg1 == 0:
 5         print(arg1, arg2)
 6     arg3 = arg1 + arg2
 7     print(arg3)
 8     if arg3 < stop:
 9         func(arg2, arg3, stop)
10 
11 func(0, 1, 60)

 1 #算法基礎之二分查找
 2 def data_search(data,find_d):
 3     mid=int(len(data)/2)
 4     if len(data)>=1:
 5         if data[mid]>find_d:
 6             print("data in thie left of [%s]"%data[mid])
 7             data_search(data[:mid],find_d)
 8         elif data[mid]<find_d:
 9             print("data in right of [%s]"%data[mid])
10             data_search(data[mid:],find_d)
11         else:
12             print("found find_d",data[mid])
13     else:
14         print("cannot find`````")
15 if __name__=="__main__":
16     data=list(range(1,60000000))
17     data_search(data,99)
18 
19 #二維數組旋轉
20 data=[[col for col in range(4)]for row in range(4)]
21 print(data)
22 for rindex,row in enumerate(data):
23     print(rindex,row)
24     for cindex in range(rindex,len(row)):
25         tmp=data[cindex][rindex]
26         data[cindex][rindex]=row[cindex]
27         data[rindex][cindex]=tmp
28     print('-------------------------')
29     for r in data:print(r)