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day05 函数和模块

今日概要：

  • 函数
  • 闭包
  • 装饰器
  • 模块
  • 自定义模块
  • 内置模块
  • 第三方模块

上节作业

  • 三元运算
简单的if else判断和赋值。

if 1==1:
  v1 = 123
else:
  v1 = 456

v1 =  123  if 条件  else 456
  • eval
def f1(arg):
    print(arg)

data_string  = "f1(123)"

eval("f1(123)")  # f1(123)

import requests


def xx(arg):
    print(arg)


res = requests.get(
    url='http://num.10010.com/NumApp/NumberCenter/qryNum?callback=xx&provinceCode=18&cityCode=188&advancePayLower=0&sortType=1&goodsNet=4&searchCategory=3&qryType=02&channel=B2C&groupKey=15237219&judgeType=1')
# print(res.text)
# print(type(res.text))

eval(res.text)

func_dict = {
    "1": "register()",
    "2": "login()",
}


def register():
    print(1)


def login():
    print(2)


eval(func_dict["1"])

1. 闭包

  • Python中是以函数为作用域。

  • 以前编写函数

def f1():
    pass

def f2():
    pass
  • 函数中嵌套函数
name = "陈聪"

def outer():
    name = "王卓"
    def inner():
        age = 19

    inner()

outer()

name = "陈聪"

def outer():
    def inner():
        print(name)
    inner()

outer()

name = "陈聪"

def outer():
    def inner():
        pass
    return inner

v = outer()
v()

def outer(name):
    def inner():
        msg = "给{}一刀".format(name)
        print(msg)
    return inner

v1 = outer("陈聪")
v2 = outer("小魏")

def func(name):
    msg = "给{}一刀".format(name)
  print(msg)

func("陈聪")
func("小魏")

1.2 线程池

import time
import requests
from concurrent.futures import ThreadPoolExecutor


def task():
    # res = requests.get("https://hbimg.huabanimg.com/51d46dc32abe7ac7f83b94c67bb88cacc46869954f478-aP4Q3V")
    # print(res)
    time.sleep(2)
    return "任务执行后的返回值"


def done(res):
    print(res)


# 内部最多可以创建10个线程的线程池
pool = ThreadPoolExecutor(10)
for i in range(500):
    # 将任务交给线程池，线程池安排线程去执行。
    future = pool.submit(task)
    future.add_done_callback(done)

def func(res):
    pass


v1 = func


def outer(xx):
    def func(res):
        pass

    return func

v1 = outer(123)

def outer(name):
    def inner():
        msg = "给{}一刀".format(name)
        print(msg)
    return inner

v1 = outer("陈聪")
v2 = outer("小魏")

v1() # 给陈聪一刀
v2() # 给小魏一刀

def outer(name):
    def inner(action):
        msg = "给{}一{}".format(name,action)
        print(msg)
    return inner

v1 = outer("陈聪") # inner函数
v2 = outer("小魏") # inner函数


v1("刀")    # 给陈聪一刀
v1("梭子")  # 给陈聪一梭子

v2("枪")    # 给小魏一枪

def outer(name):
    def inner(action):
        msg = "给{}一{}".format(name,action)
        print(msg)
    return inner

2.装饰器

def outer(a1):
    def inner():
        a1()
    return inner

def x():
    print("XX")

res = outer(x)
res()

def outer(a1):
    def inner():
        a1()
    return inner

def x():
    print("XX")

x = outer(x)
x()

def outer(a1):
    def inner():
        data = a1()
        return 123
    return inner

def x():
    return "XX"

x = outer(x)
v1 = x() # 123

def outer(a1):
    def inner():
        data = a1()
        return data
    return inner

def x():
    return "XX"

x = outer(x)
v1 = x() # "XX"

def get_data(arg):
    return arg + 100

a1 = 123
a1 = get_data(a1)
print(a1)

# 1. 执行x1函数 x1(func)，并获取他的返回值，
# 2. 将返回值再重新赋值给func
@x1
def func():
    pass

print(func)

def x1(arg):
    # arg=原来的func函数
    def inner():
        arg()
    return inner 
# func = x1(func)
@x1
def func():
    pass

func()

def x1(arg):
    # arg=原来的func函数
    def inner():
        print(123)
        res = arg() # 执行原来的func函数
        print(456)
        return res
    return inner 

@x1   # func = x1(func)
def func():
    return 123


v1 = func() # ?

def func():
    return 123

print(123)
v1 = func()
print(456)

def outer(arg):
    def inner():
        print(123)
        res = arg()
        print(456)
        return res
    return inner

@outer
def f1():
    pass

@outer
def f2():
    pass

@outer
def f3():
    pass

@outer
def f4():
    pass

@outer
def f5():
    pass

@yy
def xxxx():
    pass

案例：计算函数的执行时间

import time


def get_exec_time(arg):
    def inner():
        start = time.time()
        res = arg()
        end = time.time()
        print(end - start)
        return res

    return inner


def func():
    data = 0
    for i in range(1000000):
        data += i
    return data


@get_exec_time
def do():
    pass


v1 = func()
print(v1)

小结

def outer(func):
    def inner():
        return func()
    return inner

@outer
def do():
    return 123

v1 = do()

练习题

  1. 写一个装饰器，应用到一个函数上，在函数执行之前输出一个”before“。
def outer(func):
    def inner():
        print("123")
        return func()

    return inner


# do = outer(do)
@outer
def do():
    return 999


v1 = do()
print(v1)
  1. 写一个装饰器，应用到一个函数上，实现对原函数的返回值 + 100.
def outer(func):
    def inner():
        return func() + 100

    return inner


@outer
def do():
    return 999


v1 = do()
print(v1)
  1. 写一个装饰器，应用到一个函数上，实现执行5次代码并将结果汇总。
def outer(func):
    def inner():
        result = 0
        for i in range(5):
            res = func()
            result += res
        return result

    return inner


@outer
def do():
    return 100


v1 = do()
print(v1)

def outer(func):
    def inner(a1, a2):
        return func(a1, a2)
    return inner


@outer
def plus(v1, v2):
    return v1 + v2


value = plus(1, 2)
print(value)

def outer2(func):
    def inner(u1):
        return func(u1)

    return inner


@outer2
def do(data):
    return data + 1000


value = do(10)
print(value)

小结

def outer(func):
    def inner(*args, **kwargs):
        return func(*args, **kwargs)
    return inner

@outer
def do(data):
    return data + 1000


@outer
def plus(v1, v2):
    return v1 + v2


value1 = plus(1, 2)
print(value1)

value2 = do(10)
print(value2)

def tt(count):
    def outer(func):
        def inner(*args, **kwargs):
            return func(*args, **kwargs)

        return inner

    return outer


@tt(5)
def do(v1, v2):
    return v1 + v2


data = do(11, 22)
print(data)

案例：写装饰器，实现执行n次函数。

def loop_exec(count):
    def outer(func):
        def inner(*args, **kwargs):
            result = 0
            for i in range(count):
                data = func(*args, **kwargs)
                result += data
            return result

        return inner

    return outer


@loop_exec(5)
def get_info(a1, a2):
    return a1 + a2 + 100


res = get_info(1, 2)
print(res)

案例：Flask框架

pip install flask

Python安装目录/Scripts/pip  install flask

from flask import Flask

app = Flask(__name__)


# 以后在浏览器上输入：www.xxx.com/show/index
# @decorator
@app.route('/show/index')
def index():
    return "首页"


@app.route('/xxx/xxx/home')
def home():
    return "HOME页面"


app.run()

总结

  • 理解闭包

  • 闭包 + @语法糖

  • 装饰器的应用场景：在不改变原函数的基础上，想要在函数之前、之后定制功能。

开放封闭原则。

  • args,*kwargs解决被装饰的多个参数的问题。

  • 带参数的装饰器。

  • 装饰器

  • 传统，2层。

  • 带参数，3层。

3.模块

模块和包。

  • 模块，一个py文件。
  • 包，包含多个py文件。

image-20211128163931919

3.1 关于sys.path

# 当前运行的脚本所在目录。
/Users/wupeiqi/PycharmProjects/day05

# 忽略，这是Python自动添加的（线上运行不会有这个目录）
/Users/wupeiqi/PycharmProjects/day05
/Applications/PyCharm.app/Contents/plugins/python/helpers/pycharm_display
/Library/Frameworks/Python.framework/Versions/3.9/lib/python39.zip
/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9
/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/lib-dynload
/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages

  • 在执行Python代码时，如果要导入某个模块，默认Python寻找模块的路径：（前面找到后，就不再继续找了）

  • Python会自动条件的项目目录（忽略，线上代码就会错误）

  • 想控制Python去定义的路径下寻找模块。

import sys
sys.path.append("寻找的绝对路径")

import 模块

import os
import sys

# __file__  当前文件所在目录
# os.path.abspath(__file__) 获取文件的绝对路径
# os.path.dirname(目录)     获取上一级目录
BASE_PATH = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
sys.path.append(BASE_PATH)
# sys.path.append("/Users/wupeiqi/PycharmProjects/day05")

import utils

utils.f1()

# 当前运行的脚本所在目录。
/Users/wupeiqi/PycharmProjects/day05

# 忽略，这是Python自动添加的（线上运行不会有这个目录）
/Users/wupeiqi/PycharmProjects/day05
/Applications/PyCharm.app/Contents/plugins/python/helpers/pycharm_display
/Library/Frameworks/Python.framework/Versions/3.9/lib/python39.zip
/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9
/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/lib-dynload
/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages

image-20211128165252192

3.2 导入模块

  • import 模块
- 导入到py文件的级别。
- 使用模块中的成员时，需要全部路径都写上。
    import utils
    import handler.commons.db

    utils.f1()
    handler.commons.db.get_table()
  • from xxx import xxxx
- 级别可以到成员
  from utils import f1
    from utils import f1, f2
    from utils import *
    from utils import f2 as u2
- 导入后使用时，不需要写全路径
    from handler.commons import db
    db.get_table()

  from handler.commons.db import get_table
  get_table()

    from handler.commons import db as xx
    xx.get_table()

关于导入模块的规范：

import os
import sys
import random

import flask
import requests

import utils
from utils import (f1, f2, f1)

from handler import cache
from handler.commons import db

import os
import sys
import random

import flask
import requests

import utils
from utils import (f1, f2, f1)

from handler import cache
from handler.commons import db


def run():
    pass


if __name__ == '__main__':
    run()

约定：以后写脚本都是用这个main。

3.3 内置模块：json

v1 = '{"name":"程聪","age":99,"hobby":[11,22,33]}'  #标准的json格式内部是双引号
v2 = "{'name':'程聪',"age":99}"                     #里面用单引号的 json.loads(v2) 会报错
v3 = '{"name":"程聪","age":99,"hobby":(11,22,33)}'

3.3.1 获取数据

import requests
import json

res = requests.get(
    url="https://api.luffycity.com/api/v1/course/actual/?category_id=9"
)

# print(type(res.text))
info = json.loads(res.text)
# print(info['code'])
for item in info['data']:
    print(item['name'])

直接以Python的语法编译执行：

data_string = "{'name':'程聪','age':99}"

result = eval(data_string)   #用python代码运行
print(result)                
print(type(result))          #dict

3.3.2 响应数据

import json
from flask import Flask

app = Flask(__name__)


@app.route('/api')
def index():
    data_list = [
        (11, 22, 33, '王卓'),
        {"code": 123, 'msg': 999},
        [55, 66, True]
    ]

    data_string = json.dumps(data_list, ensure_ascii=False)
    print(data_string)

    return data_string


if __name__ == '__main__':
    app.run()

常见的JSON相关的函数：

  • json.dumps，Python数据局类型 -> JSON格式字符串（序列化）
  • json.loads， JSON格式字符串 -> Python数据局类型 （反序列化）

关于显示中文：

import json

data_list = [
    (11, 22, 33, '王卓'),
    {"code": 123, 'msg': 999},
    [55, 66, True]
]

data_string = json.dumps(data_list, ensure_ascii=False)
print(data_string)

在调用json.dumps时，不会可以讲所有的数据都序列化，对数据是有要求：

+-------------------+---------------+
| Python            | JSON          |
+===================+===============+
| dict              | object        |
+-------------------+---------------+
| list, tuple       | array         |
+-------------------+---------------+
| str               | string        |
+-------------------+---------------+
| int, float        | number        |
+-------------------+---------------+
| True              | true          |
+-------------------+---------------+
| False             | false         |
+-------------------+---------------+
| None              | null          |
+-------------------+---------------+

import json
import decimal

data_list = [11, 22, 33, str(decimal.Decimal("0.3"))]
data_string = json.dumps(data_list, ensure_ascii=False)
print(data_string)

平时自己看JSON格式用的（开发中一般不用）。

import json

string = json.dumps(data, indent=2, ensure_ascii=False)

print(string)

3.4 内置模块：time和datetime

  • 时间戳： 1638094331.760319
import time

v1 = time.time()
print(v1)
  • datetime类型：对象
import datetime

v2 = datetime.datetime.now()

print(v2, type(v2))

from datetime import datetime, timedelta

v1 = datetime.now()
v2 = v1 - timedelta(hours=3, seconds=500)
print(v2)
  • 字符串类型：2021-11-11 
import datetime

v2 = datetime.datetime.now()
string_time = v2.strftime("%Y-%m-%d %H:%M:%S")
print(string_time, type(string_time))

时间的转换：

image-20211128182153965

  • 字符串类型 -> datetime类型
from datetime import datetime

text = "2021-11-11"
v1 = datetime.strptime(text,'%Y-%m-%d') # %Y 年，%m，月份，%d，天。
print(v1)
  • datetime ->字符串类型
from datetime import datetime

v2 = datetime.now()
string_time = v2.strftime("%Y-%m-%d %H:%M:%S")
print(string_time, type(string_time))
  • 时间戳 -> datetime
import time
from datetime import datetime

ctime = time.time()  # 11213245345.123
v1 = datetime.fromtimestamp(ctime)
print(v1)
  • datetime -> 时间戳
from datetime import datetime

v1 = datetime.now()
val = v1.timestamp()
print(val)

import time

while True:
    print(123)
    time.sleep(1)

3.5 内置模块：OS（部分）

  • 拼接路径
import os

data = os.path.join("f1", 'f2', 'f3', 'xxx.png')
print(data)
  • 分隔符
print(os.path.sep)
  • 路径是否存在
import os

file_path = os.path.join('handler', 'cache.py')

v1 = os.path.exists(file_path)
print(v1)
  • 文件下的文件和文件夹
import os

file_path = os.path.join('handler')

data_list = os.listdir(file_path)
print(data_list)

import os

# win同学，自己写的路径记得加r（转义）
file_path = r"/Users/wupeiqi/PycharmProjects/day05/handler"

data_list = os.listdir(file_path)
print(data_list)
  • 文件还是文件夹
import os

file_path = r"/Users/wupeiqi/PycharmProjects/day05/handler/cache.py"

v1 = os.path.isdir(file_path)
print(v1)
  • 创建目录
import os

# file_path = r'db/xx/oo/xo'
file_path = os.path.join('db', 'xx', 'oo', 'xo')
if not os.path.exists(file_path):
    os.makedirs(file_path)