1. 生成器，使用一次后清空；
L = (x*x for x in range(10))
2. 迭代器，可用于for循环的叫可迭代对象；可被next()调用并不断返回下一个值的叫迭代器；
可用isinstance来判断
from collections import Iterable,Iterator
a = [1,2,3,4]
isinstance(a,Iterable)
3. 高阶函数:
len([1,2,3,4])
x = len
x([1,2,3]) #函数可以被拿来当做参数使用
4. map接受两个参数，一个函数，一个可迭代是对象，返回可迭代对象；函数作用在每个元素上；
x = [1,2,3]
list(map(lambda s: s*s,x)) ——[1,4,9]
5. reduce接受两个参数，函数有两个参数，将元素与下一个累积计算
from functools import reduce
reduce(lambda a,b: a-b,x) —— -4
6. filter 作用在序列元素上，返回结果是布尔型，根据true或false进行保留或删除；
x = [1,2,3,4,5,6]
list(filter(lambda s: s%2==0 or s%3==0,x))
7. 匿名函数
8.类，python3以上如下写法
class Student:
kind = "Chinese"
def __init__(self,student_id,address,score,student_name):
self.student_id = id
self.address = address
self.score = score
self.student_name = name
def getId(self):
print(self.student_id)
student = Student(10200,"Beijing",98,"xiaomi")
9.
class Student():
def __init__(self,id,name):
self.id = id
self.name = name
def getname(self):
print(self.name)
class Highschool(Student):
pass
Highschool(12345,"xiaoming")
10. collections类
——deque #对序列两端进行操作
from collections import deque
a = (x*x for x in range(100))
a.rotate()
a.dequeleft(111)
%timeit deque.a.append(100)
——counter #计数
a = list("abcdfefebdsa")
c = a.counter("a")
a.most_commom(5)
——OrderedDict
from collections import OrderedDict
d = {'banana':3,'apple':4,'pear':5,'orange':2}
OrderedDict(sorted(d.items(),key = lambda s: s[0])) #对key排序
OrderedDict(sorted(d.items(),key = lambda s: s[1])) #对value排序
10. #字符串处理
s = 'hello world '
s.strip() #去除首位空格
s.find('o') #找'o'首次在字符串中出现的位置
s.endwith('o') ——False
s.split(" ") ——切割
11. #格式化
——
a = "shanghai"
b = 33
print("今天 {0} 的气温是 {1}".format(a,b))
——
for i in range(100):
t = str(i)
print("这是我打印的第 %s 个数"%t)
12. #datatime
from datatime import datatime, timedelta
s = "20190703"
——s1 = datatime.strptime(s,"%Y%m%d")
s = "2019/06/06
——s2 = datatime.strptime(s,"Y/m/d")
——s2 -s1
——s1 + timedelta(days = 3) + timedelta(hours = 3)
13. # I/O
——
f = open("file","r")
data = f.read
f.close
——
with open("file") as handle:
data = handle.readlines() #整合前面的语句
——
f = open("file","r"，encoding = "gbk") #utf-8
——
with open("file","a") as handle:
handle.write("Hello,worle\n")
handle.write("Hello, soton") #a为附加到文件，如果写w，会覆盖原文件内容
14. #异常处理
——
try:
c = a/b
except ZeroDivisionError:
print("除数不能为0")
else:
print(c)
print(c)
——
filename = file.text
try:
withopen(filename,"r") as handle:
data = handle.read()
except FileNotFindError:
mes = "Sorry, not find" + filename
print(mes)
