day02-Python基础
>>> if a > b:
... c = a+b
... else:
... c = a-b
...
>>> c
-1
三元运算：
>>> c = a+b if a>b else a-b
>>> c
-1
1：列表、元组
列表
>>> names = ['apple','banana','orange','watermelon'] >>> names[0] 'apple' >>> names[1] 'banana' >>> names[-1] 'watermelon'
切片：取多个元素
>>> names = ['apple','orange','banana','watermelon','persimmon'] >>> names[1:4] ['orange', 'banana', 'watermelon'] >>> names[1:-1] ['orange', 'banana', 'watermelon'] >>> names[:3] ['apple', 'orange', 'banana'] >>> names[3:] ['watermelon', 'persimmon'] >>> names[3:-1] ['watermelon'] >>> names[0::2] #2代表，每隔一个元素，就取一个 ['apple', 'banana', 'persimmon'] >>> names[::2] ['apple', 'banana', 'persimmon'] >>>
>>> names ['apple', 'orange', 'banana', 'watermelon', 'persimmon'] >>> names.append('litchi') >>> names ['apple', 'orange', 'banana', 'watermelon', 'persimmon', 'litchi']
>>> names ['apple', 'orange', 'banana', 'watermelon', 'persimmon', 'litchi'] >>> names.insert(2,"从banana前插入") >>> names ['apple', 'orange', '从banana前插入', 'banana', 'watermelon', 'persimmon', 'litchi'] >>> names.insert(4,'从banana后添加') >>> names ['apple', 'orange', '从banana前插入', 'banana', '从banana后添加', 'watermelon', 'persimmon', 'litchi']
修改：
>>> names ['apple', 'orange', '从banana前插入', 'banana', '从banana后添加', 'watermelon', 'persimmon', 'litchi'] >>> names[1]="orange2" >>> names ['apple', 'orange2', '从banana前插入', 'banana', '从banana后添加', 'watermelon', 'persimmon', 'litchi']
删除：
>>> names ['apple', 'orange2', '从banana前插入', 'banana', '从banana后添加', 'watermelon', 'persimmon', 'litchi'] >>> del names[2] >>> names ['apple', 'orange2', 'banana', '从banana后添加', 'watermelon', 'persimmon', 'litchi'] >>> del names[3] >>> names ['apple', 'orange2', 'banana', 'watermelon', 'persimmon', 'litchi'] >>> names.remove("orange2") #删除指定元素 >>> names ['apple', 'banana', 'watermelon', 'persimmon', 'litchi'] >>> names.pop() #删除列表最后一个值 'litchi' >>> names ['apple', 'banana', 'watermelon', 'persimmon']
扩展：
>>> names ['apple', 'banana', 'watermelon', 'persimmon'] >>> b = [1,2,3] >>> names.extend(b) >>> names ['apple', 'banana', 'watermelon', 'persimmon', 1, 2, 3]
拷贝：
>>> names ['apple', 'banana', 'watermelon', 'persimmon', 1, 2, 3] >>> names_copy = names.copy() >>> names_copy ['apple', 'banana', 'watermelon', 'persimmon', 1, 2, 3]
统计：
>>> names ['apple', 'banana', 'watermelon', 'persimmon', 1, 2, 3] >>> names.count("apple") 1
排序&翻转：
>>> names ['apple', 'banana', 'persimmon', 'watermelon', 1, 2, 3] >>> names.sort() Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: '<' not supported between instances of 'int' and 'str' >>> names[-3] = '1' >>> names[-2] = '2' >>> names[-1] = '3' >>> names ['apple', 'banana', 'persimmon', 'watermelon', '1', '2', '3'] >>> names.sort() >>> names ['1', '2', '3', 'apple', 'banana', 'persimmon', 'watermelon'] >>> names.reverse() >>> names ['watermelon', 'persimmon', 'banana', 'apple', '3', '2', '1']
获取下标：
>>> names ['watermelon', 'persimmon', 'banana', 'apple', '3', '2', '1'] >>> names.index("banana") 2
元组
元组：只有两个方法：count、index
names = ("oracle","mysql","db2")
>>> names = ("oracle","mysql","db2") >>> names.index("mysql") 1 >>> names.count("db2") 1
元组
特性：不可修改
>>> name = "Guido" >>> name.capitalize() #首字母大写 'Guido' >>> name.casefold() #大写全部转换成小写 'guido' >>> name.center(50,"-") '----------------------Guido-----------------------' >>> name.count('do') #统计do出现的次数 1 >>> name.encode() #将字符串编码成bytes格式 b'Guido' >>> name.endswith("ui") #判断字符串是否以ui结尾 >>> "Gui\tdo".expandtabs(10) #将\t转换成多长的空格 'Gui do' False >>> name.find('G') 查找A，找到返回其索引，找不到返回-1 0
2：字符串操作
特性-不可修改
>>> name = "Guido"
>>> name.capitalize() #首字母大写
'Guido'
>>> name.casefold() #大写全部转换成小写
'guido'
>>> name.center(50,"-")
'----------------------Guido-----------------------'
>>> name.count('do') #统计do出现的次数
1
>>> name.encode() #将字符串编码成bytes格式
b'Guido'
>>> name.endswith("ui") #判断字符串是否以ui结尾
>>> "Gui\tdo".expandtabs(10) #将\t转换成多长的空格
'Gui do'
False
>>> name.find('G') 查找A，找到返回其索引，找不到返回-1
0
format :
>>> msg = "my name is {},and age is {}"
>>> msg.format("James",58)
'my name is James,and age is 58'
>>> msg = "my name is {1},and age is {0}"
>>> msg.format("James",58)
'my name is 58,and age is James'
>>> msg = "my name is {name},and age is {age}"
>>> msg.format(age=22,name="james")
'my name is james,and age is 22'
>>>
format_map：
>>> msg.format_map({'name':'james','age':58})
'my name is james,and age is 58'
>>> msg.index('i')
8
>>> '10abc'.isalnum()
True
>>> '10'.isdigit()
True
>>> name = "Scott"
>>> name.isnumeric()
False
>>> name.isprintable()
True
>>> name.isspace()
False
>>> name.istitle()
True
>>> name.isupper()
False
>>> "|".join(['Guido','Python'])
'Guido|Python'
maketrans：
>>> intab = "linus" #This is the string having actual characters.
>>> outtab = "12345" #This is the string having corresponding mapping character
>>> trantab = str.maketrans(intab,outtab)
>>> str = "this is string example....wow!"
>>> str.translate(trantab)
'th25 25 5tr23g examp1e....wow!'
>>> msg
'my name is {name},and age is {age}'
>>> msg.partition('is')
('my name ', 'is', ' {name},and age is {age}')
>>> "beijing is beautiful city!".replace("beijing","Beijing",1)
'Beijing is beautiful city!'
>>> msg.swapcase()
'MY NAME IS {NAME},AND AGE IS {AGE}'
>>> msg.zfill(40)
'000000my name is {name},and age is {age}'
>>> name ="Hello,world!"
>>> name.ljust(40,"-")
'Hello,world!----------------------------'
>>> name.rjust(40,"-")
'----------------------------Hello,world!'
>>> b="guido_james_天才"
>>> b.isidentifier() #检测一段字符串可否被当作标志符，即是否符合变量命名规则
True
