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python数据类型及其操作
一、数字
常用类型：int,float
age = 10 # int型
salary = 3000.5 # float型
进制：
二进制：
11 = 1*21 + 1*20 = 3
八进制：
11 = 1*81 + 1*80 = 9
十进制：
11 = 1*101 + 1*100 = 11
十六进制：
11 = 1*161 + 1*160 = 17
进制转换：
十进制转为二进制：
age = 10
print(bin(age)) => 0b1010
二进制转为十进制：
1010 = 1*23 + 0*22 + 1*21 + 0*20 = 10
十进制转为八进制：
print(oct(age)) => 0o12
十进制转为十六进制：
print(hex(age)) => 0xa
二、字符串
创建字符串：
>>> name = ‘johnny‘ # name = str(‘johnny‘) >>> print(type(name))
str >>> print(name[0])
j
基本操作：
移除空白
>>> name = input(‘username:‘) >>> print(name) username: johnny johnny
>>> name = name.strip()
>>> print(name)
username: johnny
johnny
或
>>> name = input(‘username‘).strip()
>>> print(name)
>>> name = ‘***johnny*****‘
>>> print(name.strip(‘*‘))
johnny
>>> print(name.lstrip(‘*‘))
johnny*****
>>> print(name.rstrip(‘*‘))
***johnny
切分
>>> user_info = ‘root:x:0:0::/root:/bin/bash‘ >>> print(user_info.split(‘:‘)) [‘root‘,‘x‘,‘0‘,‘0‘,‘‘,‘/root‘,‘/bin/bash‘] >>> print(user_info.split(‘:‘)[5]) /root
>>> msg = ‘name johnny age 10‘
>>> print(msg.split())
[‘name‘,‘johnny‘,‘age‘,‘10‘]
统计长度
>>> name = ‘johnny‘ >>> print(len(name)) #相当于 name.__len__() 6
切片
>>> name = ‘hello world‘ >>> print(name[1:3]) el >>> print(name[1]) e >>> print(name[1:9:2]) el o
其它操作
#startswith,endwith >>> name = ‘johhny_dd‘ >>> print(name.endswith(‘dd‘)) True >>> print(name.startswith(‘j‘)) True #replace >>> name = ‘ Today is a good day,choose you like‘ >>> print(name.replace(‘Today‘,‘Tomorrow‘)) Tomorrow is a good day,choose you like #format >>> print(‘{} {} {}‘.format(‘johnny‘,18,‘male‘)) johnny 18 male >>> print(‘{0} {1} {0}‘.format(‘johnny‘,18,‘male‘)) johnny 18 johnny >>> print(‘{name} {age} {sex}‘.format(name=‘johnny‘,age=18,sex=‘male‘)) johnny 18 male
>>> print(‘NAME:{name} AGE:{age} SEX:{sex}‘.format(name=‘johnny‘,age=18,sex=‘male‘))
NAME:johnny AGE:18 SEX:male #isdigit >>> num = ‘123‘ >>> print(num.isdigit()) True who_age = 10 whileTrue: age = input(‘>>:‘).strip() if len(age) == 0:continue if age.isdigit(): age = int(age) print(age,type(age))
#find,index,count >>> name = ‘johnny‘ >>> print(name.find(‘o‘)) 1 >>> print(name.find(‘x‘)) -1 >>> print(name.index(‘o‘)) 1 >>> print(name.find(‘x‘)) 报错 >>> name = ‘johnny hello‘ >>> print(name.find(‘o‘,2,4)) -1 >>> print(name.count(‘o‘)) 2 >>> print(name.count(‘o‘,0,3)) 1 #join 都必须是字符串 >>> l = [‘johnny‘,‘say‘,‘hello‘,‘world‘] >>> print(‘:‘.join(l)) johnny:say:hello:world >>> l1 = [‘johnny‘,11] >>> print(‘;‘,join(l1)) 报错
#center,ljust,rjust,zfill >>> name = ‘johnny‘ >>> print(name.center(30,‘*‘)) ************johnny************ >>> print(name.ljust(30,‘*‘)) johnny************************ >>> print(name.rjust(30,‘*‘)) ************************johnny >>> print(name.zfill(30)) 000000000000000johnny #lower,upper >>> name = ‘JOHNNY‘ >>> print(name.lower()) johnny >>> name = ‘johnny‘ >>> print(name.upper()) JOHNNY #capitalize,title >>> msg = ‘johnny say ji‘ >>> print(msg.capitalize()) Johnny say hi >>> print(msg.title) >>> Johnny Say Hi #isalnum,isalpha >>> name = ‘johnny123‘ >>> print(name.isalnum()) True >>> print(name.isalpha()) False
#in
>>> msg = ‘my name is johnny‘
>>> print(‘johnny‘ in msg)
>>> msg = ‘hello‘
>>> a,b,c,d,e = msg
>>> print(a,b,c,d,e)
h e l l o
三、列表
创建列表：
name = [‘unknown‘,‘working‘,‘safe‘]
或
name = list([‘unknown‘,‘working‘,‘safe‘])
基本操作：
索引
>>> name = [‘unknown‘,‘working‘,‘safe‘,4,6,1] >>> print(name[1]) working
切片
>>> print(name[1:3]) [‘working‘,‘safe‘]
追加,一次只能追加一个值
>>> name.append(‘hobby‘) >>> print(name) [‘unknown‘,‘working‘,‘safe‘,4,6,1,‘hobby‘]
插入
>>> name = [‘ruwee‘,‘johnny‘,‘ruwee‘,‘nihao‘,‘hello‘,‘world‘] >>> name.insert(2,‘mo‘) >>> print(name) [‘ruwee‘,‘johnny‘,‘mo‘,‘ruwee‘,‘nihao‘,‘hello‘,‘world‘]
删除 pop
>>> name.pop() #默认从后面删除,按照索引进行删除 [‘unknown‘,‘working‘,‘safe‘,4,6,1] >>> name.pop(0) [‘working‘,‘safe‘,4,6,1,‘hobby‘]
删除 remove 按照值进行删除
>>> name.remove(‘working‘) [‘safe‘,4,6,1,‘hobby‘]
长度
>>> name = [‘unknown‘,‘working‘,‘safe‘] >>> print(len(name)) 3
包含
>>> print(‘unknown‘ in name) True
其它操作
>>> my_friends = [‘ruwee‘,‘johnny‘,‘ruwee‘,‘nihao‘,‘hello‘,‘world‘] >>> my_friends.clear() #清空所有 >>> l = my_friends.copy() >>> print(l) [‘ruwee‘,‘johnny‘,‘ruwee‘,‘nihao‘,‘hello‘,‘world‘] >>> print(my_friends.count(‘ruwee‘)) 2 >>> print(my_friends.extend([‘how‘,‘are‘,‘you‘])) #一次性添加多个值 [‘ruwee‘,‘johnny‘,‘ruwee‘,‘nihao‘,‘hello‘,‘world‘,‘how‘,‘are‘,‘you‘] >>> print(my_friends.index(‘how‘)) 6 >>> print(my_friends.reverse()) [‘you‘,‘are‘,‘how‘,‘world‘,‘hello‘,‘nihao‘,‘ruwee‘,‘johnny‘,‘ruwee‘] >>> l = [4,6,1,-1] >>> l.sort() >>> print(l) [-1,1,4,6]
>>> data = http://www.mamicode.com/[‘johnny‘,22,[23,1,2]]
>>> name,age,birth = data
>>> print(name)
‘johnny‘
>>> print(age)
22
>>> print(birth)
[23,1,2]
四、字典
创建字典：
person = {‘tom‘:12,‘jerry‘:15,‘peter‘:20}
或
person = dict({‘tom‘:‘12‘,‘jerry‘:‘15‘,‘peter‘:‘20‘})
基本操作：
索引
>>> print(person[‘tom‘]) 12
新增
>>> person[‘height‘] = 1.8 >>> print(person) {‘tom‘:12,‘jerry‘:15,‘peter‘:20,‘height‘:1.8} >>> dic = {‘a‘:1,‘b‘:2} >>> person.update(dic) >>> print(person) {‘tom‘:12,‘jerry‘:15,‘peter‘:20,‘height‘:1.8,‘a‘:1,‘b‘:2}
删除
>>> person.pop(‘tom‘) >>> print(person) {‘jerry‘:15,‘peter‘:20,‘height‘:1.8} >>> print(person.pop(‘sdfdsff‘,None)) None
获取值
>>> person = {‘tom‘:12,‘jerry‘:15,‘peter‘:20}
>>> print(person.get(‘tom‘))
12
>>> print(person.get(‘sdf‘))
None
>>> print(person[‘dsf‘])
报错
键值对
>>> print(person.keys()) dict_keys([‘tom‘,‘jerry‘,‘peter‘]) >>> print(person.values()) dict_values([12,15,20]) >>> print(person.items()) dict_items([(‘tom‘,12),(‘jerry‘,15),(‘peter‘,20)])
循环
for key,value in person.items(): print(key,value)
五、集合
集合内可以有多个元素，但是每个元素都必须是不可变类型
集合内的元素唯一
集合是无序的
创建集合:
>>> s = {3,4,7,1}
或
>>>set__test = set(‘world‘)
>>>print(set_test)
{‘w‘,‘d‘,‘l‘,‘o‘,‘r‘}
>>> s1 = set(‘hello‘)
>>> print(s1)
{‘o‘,‘e‘,‘l‘,‘h‘}
基本操作:
in , not in
>>> pythons = {‘hello‘,‘how‘,‘are‘,‘you‘,‘fine‘,‘thank‘}
>>> print(‘hello‘ in pythons)
True
| 并集
>>> s1={1,10,11,22}
>>> s2 = {1,11,33}
>>> print(s1 | s2)
{1,33,10,11,22}
& 交集
>>> s1={1,10,11,22}
>>> s2 = {1,11,33}
>>> print(s1&s2)
{1,11}
- 差集
>>> s1={1,10,11,22}
>>> s2 = {1,11,33}
>>> print(s1 - s2)
{10,22}
^ 对称差集
>>> s1={1,10,11,22}
>>> s2 = {1,11,33}
>>> print(s1 ^ s2)
{33,22,10}
父集
>>> s1 = {1,2,3,4}
>>> s2 = {1,2}
>>> print(s1 >= s2)
True
子集
>>> print(s1 <= s2) False
其它操作
>>> s = set([3,5,9,10]) >>> t = set(‘Hello‘) >>> t.add(‘x‘) >>> s.update([10,37,42]) >>> t.remove(‘H‘) >>> len(s)
六、元祖
元组不可变，主要用来读
创建元祖:
age = (32,12,54,25)
或
age = tuple((32,12,54,25))
基本操作:
索引
>>> age = (32,12,54,25) >>> print(age[2]) 54
切片
>>> print(age[0:3]) (32,12,54)
长度
>>> print(len(age)) 4
包含
>>> print(12 in age) True
其它操作
>>> printt(age.index(25)) 3 >>> print(age.count(32)) 1
七、文件处理
流程：
1.打开文件，得到句柄并且赋给一个变量
2.通过句柄进行文件操作
3.关闭文件
基本操作：
读取文件
f = open(‘a.txt‘,‘r‘,encoding=‘utf-8‘) res = f.read() print(res) print(f.readline()) f.close()
with方式打开的文件在操作结束后可以自动关闭文件
with open(‘a.txt‘,‘r‘,encoding=‘utf-8‘) as f: pass
写入文件
f=open(‘a.txt‘,‘w‘,encoding=‘utf-8‘) f.write(‘11111\n‘) f.writelines([‘a\n‘,‘b\n‘,‘c\n‘]) f.close()
替换文本中的内容
import os with open(‘old.txt‘,‘r‘,encoding=‘utf-8‘) as read_f, open(‘.old.txt.swap‘,‘w‘,encoding=‘utf-8‘) as write_f: for line in read_f: if ‘SB‘ in line: line=line.replace(‘SB‘,‘alex‘) write_f.write(line) os.remove(‘old.txt‘) os.rename(‘.old.txt.swap‘,‘old.txt‘)
python数据类型及其操作
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