工作以后陆陆续续用过一些Python，今天花时间系统的看了下入门书籍《简明Python教程》(A Byte of Python)。
零、Eclipse安装PyDev
Eclipse --> Help --> Install New Software --> http://pydev.org/updates
一、字符串
1. 字符串可以用三种(其实是四种)符号表示，\'...\', "...", \'\'\'...\'\'\', """...""", 除了\'\'\'和"""能够轻松处理跨行的字符外，他们没有任何区别；
2. r"..."表示自然字符串，即忽略转义字符‘\’，这在正在表达式中很有用，可以省去大量的转义字符。
3. 字符串是不可修改的。
#!/usr/bin/python # ch04_string_test.py print \'What\\'s your name\' print "What\'s your name" print """ "What\'s your name", I asked. "John." He said. """ print "Hello python.\n" print r"Hello python.\n"
输出：
What\'s your name What\'s your name "What\'s your name", I asked. "John." He said. Hello python. Hello python.\n
二、函数
1. 用"""..."""或\'\'\'...\'\'\'可以作为函数的注释
2. 默认参数
3. 全局变量 global var
4. 关键参数 fun(val2=\'b\', val1=\'a\', ...)
5. 函数参数是reference还是copy？reference
#!/usr/bin/python # ch07_function_test.py def max_len(str1, str2=""): """ Get the max len of the two string If str2 is empty, use global g_str_list instead. """ if str2=="": global g_str_list g_str_list.append("appended") str2 = g_str_list[0] return max(len(str1), len(str2)) if __name__ == "__main__": print "max_len.__doc_ is", max_len.__doc__ print "max_len(\'x\', \'lxq\') is", max_len(\'x\', \'lxq\') g_str_list=["l is pig"] print "g_str_list:", g_str_list print "max_len(str1=\'xiong\') is", max_len(str1=\'xiong\') print "g_str_list:", g_str_list
输出：
max_len.__doc_ is Get the max len of the two string If str2 is empty, use global g_str_list instead. max_len(\'x\', \'lxq\') is 3 g_str_list: [\'l is pig\'] max_len(str1=\'xiong\') is 8 g_str_list: [\'l is pig\', \'appended\']
jxion@jxion:~/Learning/python/02_fun$ cat ./fun_ref_or_copy_test.py #!/usr/bin/python def fun(d, l): d[\'c\'] = 3 l.append(\'c\') d = {\'a\':1, \'b\':2} l = [\'a\', \'b\'] print "d:", d print "l:", l fun(d, l) print "d:", d print "l:", l jxion@jxion:~/Learning/python/02_fun$ ./fun_ref_or_copy_test.py d: {\'a\': 1, \'b\': 2} l: [\'a\', \'b\'] d: {\'a\': 1, \'c\': 3, \'b\': 2} l: [\'a\', \'b\', \'c\'] jxion@jxion:~/Learning/python/02_fun$
三、模块
1. 模块可以理解为C语言里的不同源文件，模块应该与调用者在同一目录，或者环境变量，或者import时使用相对路径。
2. 模块名即为py文件名
3. import module和from module import xxx,yyy...
1 #!/usr/bin/python 2 # my_module.py 3 4 def sayhi(): 5 print "[my_module] This is my first Python module." 6 7 version = "0.1" 8 9 if __name__ == "__main__": 10 print "[my_module] I am running by myself." 11 print "[my_module] version: ", version 12 else: 13 print "[my_module] I am being imported by another module" 14 print "[my_module] version: ", version 15 16 #!/usr/bin/python 17 # import_test.py 18 19 import my_module 20 21 my_module.sayhi() 22 print "my_module version:", my_module.version 23 24 #!/usr/bin/python 25 # fromimport_test.py 26 27 from my_module import sayhi, version 28 29 sayhi() 30 print "my_module version:", version
输出：
jxion@jxion:~/Learning/python/ch08_module$ ./import_test.py [my_module] I am being imported by another module [my_module] version: 0.1 [my_module] This is my first Python module. my_module version: 0.1 jxion@jxion:~/Learning/python/ch08_module$ ./fromimport_test.py [my_module] I am being imported by another module [my_module] version: 0.1 [my_module] This is my first Python module. my_module version: 0.1
四、数据结构
1. 一共有三种内建数据结构：
list(列表): [val1, val2, ...],
tuple(元组): (val1, val2, ...),
dict(字典): {key1:val1, key2:val2, ..}
2. list是可修改的，在Python里无处不在
3. tuple是不可修改的，用的少，常在格式化输出中使用
4. dict的key是不可修改的，val是可修改的；dict的key是没有顺序的。
5. string, list和tuple是sequence(序列), 可以使用’：‘进行一定范围索引
6. 注意list和dict在reference和copy的区别，尤其是list.
jxion@jxion:~/Learning/python/ch09_data_structure$ cat ./list_test.py #!/usr/bin/python a=[\'0\', \'12\', \'4\', \'3\'] print "a:", a print "a[0]:", a[0], "a[-1]:", a[-1] print "" a.append([200, 100]) print "a.append(100):", a print "a[-1][0]:", a[-1][0] print "" a.sort() print "a.sort():", a print "" del a[0] print "del a[0]:", a print "" jxion@jxion:~/Learning/python/ch09_data_structure$ ./list_test.py a: [\'0\', \'12\', \'4\', \'3\'] a[0]: 0 a[-1]: 3 a.append(100): [\'0\', \'12\', \'4\', \'3\', [200, 100]] a[-1][0]: 200 a.sort(): [[200, 100], \'0\', \'12\', \'3\', \'4\'] del a[0]: [\'0\', \'12\', \'3\', \'4\'] jxion@jxion:~/Learning/python/ch09_data_structure$
jxion@jxion:~/Learning/python/ch09_data_structure$ cat tuple_test.py #!/usr/bin/python age=26 name="jxion" print "%s is %20d yeas old" %(name, age) zoo1 = (\'a\', \'b\') zoo2 = (\'a\', \'c\') zoo_combined = (zoo1, zoo2) print "zoo1:", zoo1 print "zoo2:", zoo2 print "zoo_combined:", zoo_combined jxion@jxion:~/Learning/python/ch09_data_structure$ ./tuple_test.py jxion is 26 yeas old zoo1: (\'a\', \'b\') zoo2: (\'a\', \'c\') zoo_combined: ((\'a\', \'b\'), (\'a\', \'c\')) jxion@jxion:~/Learning/python/ch09_data_structure$
jxion@jxion:~/Learning/python/ch09_data_structure$ cat dict_test.py #!/usr/bin/python d = {\'a\':1, \'c\':3, \'b\':2} print "d:", d print "d.items():", d.items() print "Traverse d:" for mykey, myvalue in d.items(): print mykey, myvalue print "" # add a key-val d[\'aa\'] = 0 print "d:", d print "Traverse d:" for mykey, myvalue in d.items(): print mykey, myvalue print "" if \'c\' in d: print "\'c\' is in d, the val is", d[\'c\'] jxion@jxion:~/Learning/python/ch09_data_structure$ ./dict_test.py d: {\'a\': 1, \'c\': 3, \'b\': 2} d.items(): [(\'a\', 1), (\'c\', 3), (\'b\', 2)] Traverse d: a 1 c 3 b 2 d: {\'a\': 1, \'aa\': 0, \'c\': 3, \'b\': 2} Traverse d: a 1 aa 0 c 3 b 2 \'c\' is in d, the val is 3 jxion@jxion:~/Learning/python/ch09_data_structure$
jxion@jxion:~/Learning/python/ch09_data_structure$ cat seq_list_tuple_string_test.py #!/usr/bin/python # list my_list = [\'apple\', \'mango\', \'carrot\', \'banana\'] print \'my_list: \', my_list print \'my_list[0]: \', my_list[0] print \'my_list[-1]: \', my_list[-1] print \'my_list[1:3]:\', my_list[1:3] print \'my_list[1:]: \', my_list[2:] print \'my_list[1:-1]\', my_list[1:-1] print \'my_list[:] \', my_list[:] print "" # tuple my_tuple = (\'apple\', \'mango\', \'carrot\', \'banana\') print \'my_tuple: \', my_tuple print \'my_tuple[0]: \', my_tuple[0] print \'my_tuple[-1]: \', my_tuple[-1] print \'my_tuple[1:3]:\', my_tuple[1:3] print \'my_tuple[1:]: \', my_tuple[2:] print \'my_tuple[1:-1]\', my_tuple[1:-1] print \'my_tuple[:] \', my_tuple[:] print "" #string my_string = \'apple\' print \'my_string: \', my_string print \'my_string[0]: \', my_string[0] print \'my_string[-1]: \', my_string[-1] print \'my_string[1:3]:\', my_string[1:3] print \'my_string[1:]: \', my_string[2:] print \'my_string[1:-1]\', my_string[1:-1] print \'my_string[:] \', my_string[:] print "" jxion@jxion:~/Learning/python/ch09_data_structure$ ./seq_list_tuple_string_test.py my_list: [\'apple\', \'mango\', \'carrot\', \'banana\'] my_list[0]: apple my_list[-1]: banana my_list[1:3]: [\'mango\', \'carrot\'] my_list[1:]: [\'carrot\', \'banana\'] my_list[1:-1] [\'mango\', \'carrot\'] my_list[:] [\'apple\', \'mango\', \'carrot\', \'banana\'] my_tuple: (\'apple\', \'mango\', \'carrot\', \'banana\') my_tuple[0]: apple my_tuple[-1]: banana my_tuple[1:3]: (\'mango\', \'carrot\') my_tuple[1:]: (\'carrot\', \'banana\') my_tuple[1:-1] (\'mango\', \'carrot\') my_tuple[:] (\'apple\', \'mango\', \'carrot\', \'banana\') my_string: apple my_string[0]: a my_string[-1]: e my_string[1:3]: pp my_string[1:]: ple my_string[1:-1] ppl my_string[:] apple jxion@jxion:~/Learning/python/ch09_data_structure$
jxion@jxion:~/Learning/python/ch09_data_structure$ cat ./reference_copy_test.py #!/usr/bin/python def list_test(): src = [\'a\', \'b\', \'c\'] ref = src copy = src[:] del ref[0] del copy[-1] print "src:", src print "ref:", ref print "copy:", copy def dict_test(): src = {\'a\':1, \'b\':2, \'c\':3} ref = src #icopy = src[:] del ref[\'a\'] #def copy[-1] print "src:", src print "ref:", ref #print "copy:", copy list_test() print "" dict_test() print "" jxion@jxion:~/Learning/python/ch09_data_structure$ ./reference_copy_test.py src: [\'b\', \'c\'] ref: [\'b\', \'c\'] copy: [\'a\', \'b\'] src: {\'c\': 3, \'b\': 2} ref: {\'c\': 3, \'b\': 2} jxion@jxion:~/Learning/python/ch09_data_structure$
五、面向对象编程
1. 成员变量：static，private&public
2. 成员函数：构造&析构函数，static，private&public
3. 继承
jxion@jxion:~/Learning/python/ch11_OOP$ cat class_test.py #!/usr/bin/python class Person: \'\'\'Represents a person.\'\'\' num = 0 # static variable # constructor def __init__(self, name, age = 10000): self.name = name # public variable self.__age = age # private variable Person.num += 1 # destructor def __del__(self): Person.num -= 1 print \'%s has left. There are still %d people here.\' %(self.name, Person.num) # private method def __get_greeting_words(self): return \'Hi, my name is %s. I am %d years old.\' % (self.name, self.__age) # public method def sayHi(self): print self.__get_greeting_words() # static method @staticmethod def howMany(): print \'We have %d persons here.\' % Person.num if __name__ == "__main__": p1 = Person(\'p1\', 26) p1.sayHi() p1.howMany() # OK Person.howMany() # OK too p2 = Person(\'p2\') p2.sayHi() p2.howMany() jxion@jxion:~/Learning/python/ch11_OOP$ ./class_test.py Hi, my name is p1. I am 26 years old. We have 1 persons here. We have 1 persons here. Hi, my name is p2. I am 10000 years old. We have 2 persons here. p2 has left. There are still 1 people here. p1 has left. There are still 0 people here. jxion@jxion:~/Learning/python/ch11_OOP$
jxion@jxion:~/Learning/python/ch11_OOP$ cat inherit_test.py #!/usr/bin/python class SchoolMember: \'\'\'Represents any school member.\'\'\' def __init__(self,name,age): self.name=name self.age=age def tell(self): print \'Name:"%s" Age:"%s"\' %(self.name,self.age), class Teacher(SchoolMember): \'\'\'Represents a teacher.\'\'\' def __init__(self,name,age,salary): SchoolMember.__init__(self,name,age) self.salary=salary def tell(self): SchoolMember.tell(self) print \'Salary: "%d"\' %self.salary class Student(SchoolMember): \'\'\'Represents a student.\'\'\' def __init__(self,name,age,marks): SchoolMember.__init__(self,name,age) self.marks=marks def tell(self): SchoolMember.tell(self) print \'Marks: "%d"\' %self.marks t=Teacher(\'Mrs. Shrividya\',40,30000) s=Student(\'Swaroop\',22,75) members=[t,s] for member in members: member.tell() # works for both Teachers and Students jxion@jxion:~/Learning/python/ch11_OOP$ ./inherit_test.py Name:"Mrs. Shrividya" Age:"40" Salary: "30000" Name:"Swaroop" Age:"22" Marks: "75" jxion@jxion:~/Learning/python/ch11_OOP$
六、异常
TBD。这部分平时关注的不多，也就没什么体会了。
七、其他
1. 列表综合list comprehension
2. lambda表示式：匿名函数，返回值为一个函数
jxion@jxion:~/Learning/python$ cat ch15_list_comprehension_test.py #!/usr/bin/python src_l = [2, 3, 4] des_l = [2*elem for elem in src_l if elem > 2] print "src_l:", src_l print "des_l:", des_l jxion@jxion:~/Learning/python$ ./ch15_list_comprehension_test.py src_l: [2, 3, 4] des_l: [6, 8] jxion@jxion:~/Learning/python$
jxion@jxion:~/Learning/python$ cat ./ch15_lambda_test.py #!/usr/bin/python # lambda statement returns a function name. # before \':\' is: arguments list of the function # after \':\' is: return value of the function lmd = lambda x, y : x**y print "lmd(3, 4):", lmd(3, 4) print "pow(3, 4):", pow(3, 4) jxion@jxion:~/Learning/python$ ./ch15_lambda_test.py lmd(3, 4): 81 pow(3, 4): 81 jxion@jxion:~/Learning/python$