一些好用的函数或方法

一、zip
zip函数可以把两个函数压缩在一起，然后返回一个内含元组的列表。如果两个序列不等长，当最短的序列用完时就会停止。
示例代码：

names = ['dnfag','anne','damon','Jhon','David']
ages = [20,25,30,35,40,45]
for name,age in zip(names,ages):
    print(f'{name} is {age} years old')

返回结果：
dnfag is 20 years old
anne is 25 years old
damon is 30 years old
Jhon is 35 years old
David is 40 years old

二、enumerate
enumerate函数可以获取列表对应的索引和元素：
示例代码：

names = ['dnfag','anne','damon','Jhon','David']
for index,name in enumerate(names):
    print(index,name)

返回结果：
0 dnfag
1 anne
2 damon
3 Jhon
4 David
enumerate函数用于字典时也可以获取到字典的key及对应的索引，而且是按原来的顺序排列好的，如果想按字典的原顺序读取数据，这个还是有用处的：

names = {'dnfag':20,'anne':25,'damon':30,'Jhon':35,'David':40}
for index,name in enumerate(names):
    print(index,name)
    print(name,names[name])

返回结果：
0 dnfag
dnfag 20
1 anne
anne 25
2 damon
damon 30
3 Jhon
Jhon 35
4 David
David 40

三、isinstance
isinstance 用来判断一个对象是否是一个已知的类型。函数返回值是布尔值。若对象的类型是已知类型，那么就返回True.否则返回False.用法：
isinstance(对象，对象类型)
对象类型有：int,float,bool,str,list,turple,set,dict
对象类型可以有多个，只要一个符合就返回True.如：

a = "abc"
isinstance(a,(int,str,float))

会返回True

四、pickle

pickle模块实现了基本的数据序列化和反序列化。通过pickle模块的序列化操作，我们能够将程序中运行的对象信息保存到文件中并永久存储。通过pickle模块的反序列化操作，我们能够从文件中创建上一次程序保存的对象

import pickle
data0 = "Hello World"
data1 = list(range(20))[1::2]
data2 = ("x","y","z")
data3 = {"a":data0,"b":data1,"c":data2}

print(data0)
print(data1)
print(data2)
print(data3)

#序列化
output = open("data.pk1","wb")
pickle.dump(data0,output)
pickle.dump(data1,output)
pickle.dump(data2,output)
pickle.dump(data3,output)
output.close()
#反序列化
pkl_file = open("data.pk1","rb")
data0 = pickle.load(pkl_file)
data1 = pickle.load(pkl_file)
data2 = pickle.load(pkl_file)
data3 = pickle.load(pkl_file)

print(data0)
print(data1)
print(data2)
print(data3)
pkl_file.close()

返回结果：

Hello World
[1, 3, 5, 7, 9, 11, 13, 15, 17, 19]
('x', 'y', 'z')
{'a': 'Hello World', 'b': [1, 3, 5, 7, 9, 11, 13, 15, 17, 19], 'c': ('x', 'y', 'z')}
Hello World
[1, 3, 5, 7, 9, 11, 13, 15, 17, 19]
('x', 'y', 'z')
{'a': 'Hello World', 'b': [1, 3, 5, 7, 9, 11, 13, 15, 17, 19], 'c': ('x', 'y', 'z')}