Python基础之元组与文件知识总结

>>> t = (1,2,3,4,5)
>>> t[0] = 2
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'tuple' object does not support item assignment

>>> t
(1, 2, 3, 4, 5)
>>> t.index(3)
2
>>> t.count(3)
1

(1,2) #定义一个元组
(1, 2)
(1,2)+(3,4)#增加元组
(1, 2, 3, 4)

t=[1,2,3,4,5]
res=[x**2 for x in t] #计算出t中元素的平方并放在res中
res
[1, 4, 9, 16, 25]
t.index(3) #检索3的位置
2
t.count(3) #数元组t中3的个数
1

from collections import namedtuple #引入namedtuple给员工赋值
employee=namedtuple("employee",["named","age","department","salary"]) #定义一个员工模板
Jerry=employee("Jerry",30,"财务部","9000.00")#给名叫Jerry的员工赋值
Jerry
employee(named='Jerry', age=30, department='财务部', salary='9000.00')
Jerry.age #读取Jerry的年龄
30

>>> myfile = open('hello.txt','w') #若没有，自动创建文件

>>> myfile = open('hello.txt','w')
>>> myfile.write("你好啊，我叫赛利亚\n") #写操作
10
>>> myfile.close()

>>> f = open('hello.txt')
>>> f.read()
'你好啊，我叫赛利亚\n'
>>> f.read()
''
>>> f = open('hello.txt')
>>> f.readline()                      #readline一次读取一行，返回字符串
'你好啊，我叫赛利亚\n'
>>> f.readline()
''
>>> l = open('hello.txt').readlines() #readline一次读取全部行，返回列表
>>> l
['你好啊，我叫赛利亚\n']

>>> f = open('hello.txt')
>>> f.read()
'你好啊，我叫赛利亚\n'
>>> f.read()
''
>>> f = open('hello.txt')
>>> f.readline()                      #readline一次读取一行，返回字符串
'你好啊，我叫赛利亚\n'
>>> f.readline()
''
>>> l = open('hello.txt').readlines() #readline一次读取全部行，返回列表
>>> l
['你好啊，我叫赛利亚\n']

# file = open("demo1/1.txt","rb")
file = open("demo1/1.png","rb")
ret = file.read()  #b'huangzhi'   huangzhi
print(ret)
file.close()

file = open("demo1/1.txt","r+")
# ret = file.read() #读取全部内容
# print(ret) 
file.write("guyin") #从头写入，原有内容会逐渐被覆盖
file.close()

from demo1.img import img2
file = open("demo1/2.jpg","wb")
file.write(img2)
file.close()

file = open("demo1/1.txt","w+")
file.write("hello world")
ret = file.read()
print(ret)
file.close()

#在demo1下的111.txt中追加“guyin”
# file = open("demo1/111.txt","a")
file = open("demo1/3.txt","a")
file.write("guyin")
file.close()

file = open("demo1/111.txt","a+")
file.write("yangyong")
ret = file.read()
print(ret)
file.close()

f = open('datafile.pkl','wb')
>>> import pickle
>>> d = {'a':1,'b':2}
>>> pickle.dump(d,f)
>>> f.close()
 
 
>>> f = open('datafile.pkl','rb')
>>> data = pickle.load(f)
>>> data
{'a': 1, 'b': 2}