python基础-函数(lambda表达式、函数作参数、内置函数、推导式)和pip

函数进阶

• 今日概要:

  • 函数名就是一个变量(扩展)

  • 匿名函数(lambda表达式)

  • 重点内置函数——python内置函数

  • 推导式(一行代码生成数据)

1. 函数名就是变量

def func():
    pass

v1 = func

v1()
func()

def register():
    ...

def login():
    ...

def show_users():
    ...

print("welcome to xxx system!")
print("1. Register | 2. Login | 3. Show all members")

choice = input("please choose a number")
choice = int(choice)

func_list = [register, login, show_users]
func_list[choice - 1]()

让函数当做字典的值。

def func():
    print(123)
    return 123

func_dict = {
    "1": func,
    "2": func,
    "3": func
}

# 获取函数并执行
func_dict["2"]()

#
func_object = func_dict.get("1")
if func_object == None:
    print("函数不存在。")
else:
    func_object()

案例1: 用户管理系统(VVIP版本)

用户登录系统显示： 1. login 2. register 3. search

def register():
    print("register")

def login():
    print("login")

def show_users():
    print("show_users")

print("welcome to xxx system!")
print("1. Register | 2. Login | 3. Show all members")

choice = input("please choose a number \n>>> ")

func_dict = {
    "1": register,
    "2": login,
    "3": show_users
}

func_object = func_dict.get(choice)
if func_object is None:
    print("function is not exist!")
else:
    func_object()

稍微改进一下：

def register():
    print("register")

def login():
    print("login")

def show_users():
    print("show_users")

print("welcome to xxx system!")
print("1. Register | 2. Login | 3. Show all members")

choice = input("please choose a number \n>>> ")

func_dict = {
    "1": register,
    "2": login,
    "3": show_users
}

func_object = func_dict.get(choice)

if not func_object:  # 修改了这一行
    print("function is not exist!")
else:
    func_object()

案例2 资源下载管理器

• 系统有三大专区，图片 NBA 短视频

• 每个专区定义一个函数

• 用户选择

  • 选对了，进入

  • 选错了/重复选择 错误提示

  • Q/q 终止

• 图片专区

  • 罗列图片名称和序号
  • 让用户选择序号，用户选择哪个图片，我们帮助用户下载
  • 再次提示用户输入是否继续 如果是n/N返回上一级(让用户重新选择专区)

# ************************************* 我自己的 *************************************

# 图片专区
img_data = {
    "1": ("image1", r"https://pic.3gbizhi.com/uploadmark/20230825/979bcabfd305afce4b5b5d00e467e01f.jpg"),
    "2": ("image2", r"https://pic.3gbizhi.com/uploadmark/20220916/35c9f1a1e642ba133b0efc2b58b9ae02.png"),
    "3": ("image3", r"https://pic.3gbizhi.com/uploadmark/20190912/6d7abd46d1531635e9b187cdea724345.jpg"),
    "4": ("image4", r"https://pic.3gbizhi.com/uploadmark/20231120/004a59dc1b775ee4ea19cb9f350682bc.jpg"),
    "5": ("image5", r"https://pic.3gbizhi.com/uploadmark/20231030/d74c8cbc8bb461cef094e6b686990fde.jpg"),
    "6": ("image6", r"https://pic.netbian.com/uploads/allimg/230405/000245-168062416593ad.jpg")
}

# NBA 专区
nba_data = {
    "1": {
        "title": "title1",
        "url": r"https://v3-web.douyinvod.com/5f859c5bcc8097014fe28d4aa0a51c85/65da090c/video/tos/cn/tos-cn-ve-15/oMGs"
               r"fhDALWBH8UmrCmFEAeDhBqA7L14IQBfmE6/?a=6383&ch=5&cr=3&dr=0&lr=all&cd=0%7C0%7C0%7C3&cv=1&br=1721&bt="
               r"1721&cs=0&ds=6&ft=bvTKJbQQqUnXfmoZmo0ORVTYA0pikecsejKJV7TYeo0P3-I&mime_type=video_mp4&qs=0&rc=OGY1Oz"
               r"VmNWQ5aTU4OWY1OEBpM2RnO205cjt3cTMzNGkzM0AzMy1iMzA1XmMxYjAxNmA1YSMtM24tMmRjY15gLS1kLS9zcw%3D%3D&btag"
               r"=e00028000&dy_q=1708784219&feature_id=f0150a16a324336cda5d6dd0b69ed299&l=20240224221658C1E7B1B597C2"
               r"A7D01ABA"
    },
    "2": {
        "title": "title2",
        "url": r"https://v3-web.douyinvod.com/f3e00fdf66b9fa32014f76739ce9a6c2/65da0964/video/tos/cn/tos-cn-ve-15"
               r"/ocw45QDzyBEJirkfhQCGnAIsAA7ZN7MgAeE5LX/?a=6383&ch=5&cr=3&dr=0&lr=all&cd=0%7C0%7C0%7C3&cv=1&br="
               r"817&bt=817&cs=0&ds=6&ft=bvTKJbQQqUnXfmoZmo0ORVTYA0pi9vcsejKJV7TYeo0P3-I&mime_type=video_mp4&qs="
               r"0&rc=N2U2OGc0OGhkZWZmaGlnOUBpMzVoMzw6ZmVncTMzNGkzM0AxMjBjMzUzXzUxMDQuNi5gYSNsNjRqcjRnbGBgLS1kLT"
               r"Bzcw%3D%3D&btag=e00028000&dy_q=1708784308&feature_id=f0150a16a324336cda5d6dd0b69ed299&l=20240224"
               r"221827BDAEFE7D705F16E75C4C"
    }
}

# 短视频专区
short_video_data = {
    "1": {
        "title": "title1",
        "url": r"https://v3-web.douyinvod.com/5f859c5bcc8097014fe28d4aa0a51c85/65da090c/video/tos/cn/tos-cn-ve-15"
               r"/oMGsfhDALWBH8UmrCmFEAeDhBqA7L14IQBfmE6/?a=6383&ch=5&cr=3&dr=0&lr=all&cd=0%7C0%7C0%7C3&cv=1&br="
               r"1721&bt=1721&cs=0&ds=6&ft=bvTKJbQQqUnXfmoZmo0ORVTYA0pikecsejKJV7TYeo0P3-I&mime_type=video_mp4&qs"
               r"=0&rc=OGY1OzVmNWQ5aTU4OWY1OEBpM2RnO205cjt3cTMzNGkzM0AzMy1iMzA1XmMxYjAxNmA1YSMtM24tMmRjY15gLS1kL"
               r"S9zcw%3D%3D&btag=e00028000&dy_q=1708784219&feature_id=f0150a16a324336cda5d6dd0b69ed299&l=202402"
               r"24221658C1E7B1B597C2A7D01ABA"
    },
    "2": {
        "title": "title2",
        "url": r"https://v3-web.douyinvod.com/f3e00fdf66b9fa32014f76739ce9a6c2/65da0964/video/tos/cn/tos-cn-ve"
               r"-15/ocw45QDzyBEJirkfhQCGnAIsAA7ZN7MgAeE5LX/?a=6383&ch=5&cr=3&dr=0&lr=all&cd=0%7C0%7C0%7C3&cv"
               r"=1&br=817&bt=817&cs=0&ds=6&ft=bvTKJbQQqUnXfmoZmo0ORVTYA0pi9vcsejKJV7TYeo0P3-I&mime_type=video"
               r"_mp4&qs=0&rc=N2U2OGc0OGhkZWZmaGlnOUBpMzVoMzw6ZmVncTMzNGkzM0AxMjBjMzUzXzUxMDQuNi5gYSNsNjRqcjRnb"
               r"GBgLS1kLTBzcw%3D%3D&btag=e00028000&dy_q=1708784308&feature_id=f0150a16a324336cda5d6dd0b69ed29"
               r"9&l=20240224221827BDAEFE7D705F16E75C4C"
    }
}

def image_area():
    img_num = input("choose the number of images!\n>>> ")

    print("download image ...")
    print(img_data[img_num][0], " ", img_data[img_num][1])
    print("download image over.")

    print("if you want to download the image again? If you want, input n/N else input y/Y.")
    if_repeat = input(">>> ")
    if if_repeat.upper() == "Y":
        image_area()
    elif if_repeat.upper() == "N":
        print()
        return
    else:
        raise ValueError("input error: {}".format(if_repeat))
    print()

def nba_area():
    img_num = input("choose the number of nba images!\n>>> ")

    print("download image ...")
    print(nba_data[img_num]["title"], " ", nba_data[img_num]["url"])
    print("download image over.")

    print("if you want to download the image again? If you want, input n/N else input y/Y.")
    if_repeat = input(">>> ")
    if if_repeat.upper() == "Y":
        nba_area()
    elif if_repeat.upper() == "N":
        print()
        return
    else:
        raise ValueError("input error: {}".format(if_repeat))
    print()

def video_area():
    img_num = input("choose the number of video!\n>>> ")

    print("download image ...")
    print(short_video_data[img_num]["title"], " ", short_video_data[img_num]["url"])
    print("download image over.")

    print("if you want to download the image again? If you want, input n/N else input y/Y.")
    if_repeat = input("please input your choice: \n>>> ")
    if if_repeat.upper() == "Y":
        nba_area()
    elif if_repeat.upper() == "N":
        print()
        return
    else:
        raise ValueError("input error: {}".format(if_repeat))
    print()

def main():
    function_dict = {
        "1": image_area,
        "2": nba_area,
        "3": video_area,
    }

    while True:
        print("1. image 2. nba 3. short video")
        choice = input("choose a number, input Q or q to exit.\n>>> ")
        if choice.upper() == "Q":
            break

        func_obj = function_dict.get(choice)
        if not func_obj:
            raise ValueError("input error: {}".format(choice))
        func_obj()
    print()

if __name__ == "__main__":
    main()

# ************************************* 沛齐老师的 *************************************
import sys

# 图片专区
img_data = {
    "1": ("image1", r"https://pic.3gbizhi.com/uploadmark/20230825/979bcabfd305afce4b5b5d00e467e01f.jpg"),
    "2": ("image2", r"https://pic.3gbizhi.com/uploadmark/20220916/35c9f1a1e642ba133b0efc2b58b9ae02.png"),
    "3": ("image3", r"https://pic.3gbizhi.com/uploadmark/20190912/6d7abd46d1531635e9b187cdea724345.jpg"),
    "4": ("image4", r"https://pic.3gbizhi.com/uploadmark/20231120/004a59dc1b775ee4ea19cb9f350682bc.jpg"),
    "5": ("image5", r"https://pic.3gbizhi.com/uploadmark/20231030/d74c8cbc8bb461cef094e6b686990fde.jpg"),
    "6": ("image6", r"https://pic.netbian.com/uploads/allimg/230405/000245-168062416593ad.jpg")
}

# NBA 专区
nba_data = {
    "1": {
        "title": "title1",
        "url": r"https://v3-web.douyinvod.com/5f859c5bcc8097014fe28d4aa0a51c85/65da090c/video/tos/cn/tos-cn-ve-15/oMGs"
        r"fhDALWBH8UmrCmFEAeDhBqA7L14IQBfmE6/?a=6383&ch=5&cr=3&dr=0&lr=all&cd=0%7C0%7C0%7C3&cv=1&br=1721&bt="
        r"1721&cs=0&ds=6&ft=bvTKJbQQqUnXfmoZmo0ORVTYA0pikecsejKJV7TYeo0P3-I&mime_type=video_mp4&qs=0&rc=OGY1Oz"
        r"VmNWQ5aTU4OWY1OEBpM2RnO205cjt3cTMzNGkzM0AzMy1iMzA1XmMxYjAxNmA1YSMtM24tMmRjY15gLS1kLS9zcw%3D%3D&btag"
        r"=e00028000&dy_q=1708784219&feature_id=f0150a16a324336cda5d6dd0b69ed299&l=20240224221658C1E7B1B597C2"
        r"A7D01ABA"},
    "2": {
        "title": "title2",
        "url": r"https://v3-web.douyinvod.com/f3e00fdf66b9fa32014f76739ce9a6c2/65da0964/video/tos/cn/tos-cn-ve-15"
        r"/ocw45QDzyBEJirkfhQCGnAIsAA7ZN7MgAeE5LX/?a=6383&ch=5&cr=3&dr=0&lr=all&cd=0%7C0%7C0%7C3&cv=1&br="
        r"817&bt=817&cs=0&ds=6&ft=bvTKJbQQqUnXfmoZmo0ORVTYA0pi9vcsejKJV7TYeo0P3-I&mime_type=video_mp4&qs="
        r"0&rc=N2U2OGc0OGhkZWZmaGlnOUBpMzVoMzw6ZmVncTMzNGkzM0AxMjBjMzUzXzUxMDQuNi5gYSNsNjRqcjRnbGBgLS1kLT"
        r"Bzcw%3D%3D&btag=e00028000&dy_q=1708784308&feature_id=f0150a16a324336cda5d6dd0b69ed299&l=20240224"
        r"221827BDAEFE7D705F16E75C4C"}}

# 短视频专区
short_video_data = {
    "1": {
        "title": "title1",
        "url": r"https://v3-web.douyinvod.com/5f859c5bcc8097014fe28d4aa0a51c85/65da090c/video/tos/cn/tos-cn-ve-15"
               r"/oMGsfhDALWBH8UmrCmFEAeDhBqA7L14IQBfmE6/?a=6383&ch=5&cr=3&dr=0&lr=all&cd=0%7C0%7C0%7C3&cv=1&br="
               r"1721&bt=1721&cs=0&ds=6&ft=bvTKJbQQqUnXfmoZmo0ORVTYA0pikecsejKJV7TYeo0P3-I&mime_type=video_mp4&qs"
               r"=0&rc=OGY1OzVmNWQ5aTU4OWY1OEBpM2RnO205cjt3cTMzNGkzM0AzMy1iMzA1XmMxYjAxNmA1YSMtM24tMmRjY15gLS1kL"
               r"S9zcw%3D%3D&btag=e00028000&dy_q=1708784219&feature_id=f0150a16a324336cda5d6dd0b69ed299&l=202402"
               r"24221658C1E7B1B597C2A7D01ABA"
    },
    "2": {
        "title": "title2",
        "url": r"https://v3-web.douyinvod.com/f3e00fdf66b9fa32014f76739ce9a6c2/65da0964/video/tos/cn/tos-cn-ve"
               r"-15/ocw45QDzyBEJirkfhQCGnAIsAA7ZN7MgAeE5LX/?a=6383&ch=5&cr=3&dr=0&lr=all&cd=0%7C0%7C0%7C3&cv"
               r"=1&br=817&bt=817&cs=0&ds=6&ft=bvTKJbQQqUnXfmoZmo0ORVTYA0pi9vcsejKJV7TYeo0P3-I&mime_type=video"
               r"_mp4&qs=0&rc=N2U2OGc0OGhkZWZmaGlnOUBpMzVoMzw6ZmVncTMzNGkzM0AxMjBjMzUzXzUxMDQuNi5gYSNsNjRqcjRnb"
               r"GBgLS1kLTBzcw%3D%3D&btag=e00028000&dy_q=1708784308&feature_id=f0150a16a324336cda5d6dd0b69ed29"
               r"9&l=20240224221827BDAEFE7D705F16E75C4C"
    }
}

def image_area():
    print("======================== you are now in image area ========================")
    msg_list = []
    for k, item in img_data.items():
        string = "{}-{}".format(k, item[0])
        msg_list.append(string)
    msg_string = ": ".join(msg_list)
    while True:
        print(msg_string)
        img_num = input("choose the number of images!\n>>> ")
        if img_num.upper() == "N":
            return
        item_tuple = img_data.get(img_num)

        if not item_tuple:
            print("index error, please try again.", file=sys.stderr)
            continue
        print("correct index, downloading image ...")
        # print(img_data[img_num][0], " ", img_data[img_num][1])
        title, url = item_tuple
        print(title, url)
        print("download image over.")

        # print("if you want to download the image again? If you want, input n/N else input y/Y.")
        # if_repeat = input(">>> ")
        # if if_repeat.upper() == "Y":
        #     image_area()
        # elif if_repeat.upper() == "N":
        #     print()
        #     return
        # else:
        #     raise ValueError("input error: {}".format(if_repeat))
        # print()

def nba_area():
    img_num = input("choose the number of nba images!\n>>> ")

    print("download image ...")
    print(nba_data[img_num]["title"], " ", nba_data[img_num]["url"])
    print("download image over.")

    print("if you want to download the image again? If you want, input n/N else input y/Y.")
    if_repeat = input(">>> ")
    if if_repeat.upper() == "Y":
        nba_area()
    elif if_repeat.upper() == "N":
        print()
        return
    else:
        raise ValueError("input error: {}".format(if_repeat))
    print()

def video_area():
    img_num = input("choose the number of video!\n>>> ")

    print("download image ...")
    print(short_video_data[img_num]["title"],
          " ", short_video_data[img_num]["url"])
    print("download image over.")

    print("if you want to download the image again? If you want, input n/N else input y/Y.")
    if_repeat = input("please input your choice: \n>>> ")
    if if_repeat.upper() == "Y":
        nba_area()
    elif if_repeat.upper() == "N":
        print()
        return
    else:
        raise ValueError("input error: {}".format(if_repeat))
    print()

def run():
    function_dict = {
        "1": image_area,
        "2": nba_area,
        "3": video_area,
    }

    while True:
        print("1. image 2. nba 3. short video")
        choice = input("choose a number, input Q or q to exit.\n>>> ")
        if choice.upper() == "Q":
            break

        func_obj = function_dict.get(choice)
        if not func_obj:
            # raise ValueError("input error: {}".format(choice))
            print("input error, try again: ", file=sys.stderr)
            continue
        func_obj()
    print()

if __name__ == "__main__":
    run()

# --END--

注意: 只根据老师的代码修改了images这个专区的代码，其他的代码逻辑相同，不再浪费时间写了；此外，我加了一行代码import sys这里面有一个sys.stderr，可以当做参数传到print函数里面，这样带有file=sys.stderr的print语句所打印出来的语句就是红色的。

下载功能的实现

注意：如果没有安装requests第三方库，需要自己下载一下：在pycharm中，打开terminal，输入pip install requests，等待下载完成即可。

# 安装第三方模块进行下载
import requests

# 下载图片
url_list = [
    "https://pic.3gbizhi.com/uploadmark/20230825/979bcabfd305afce4b5b5d00e467e01f.jpg",
    "https://pic.3gbizhi.com/uploadmark/20220916/35c9f1a1e642ba133b0efc2b58b9ae02.png",
    "https://pic.3gbizhi.com/uploadmark/20190912/6d7abd46d1531635e9b187cdea724345.jpg",
    "https://pic.3gbizhi.com/uploadmark/20231120/004a59dc1b775ee4ea19cb9f350682bc.jpg",
    "https://pic.3gbizhi.com/uploadmark/20231030/d74c8cbc8bb461cef094e6b686990fde.jpg",
    "https://pic.netbian.com/uploads/allimg/230405/000245-168062416593ad.jpg"
]
headers = {
    "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) "
                  "Chrome/99.0.4844.84 Safari/537.36 HBPC/12.1.3.306"
}
i = 0
for item in url_list:
    # 下载文件
    res = requests.get(
        url=item,
        headers=headers
    )
    # 保存文件

    with open("./images/image" + str(i) + ".jpg", "wb") as fp:
        print("downloading", i)
        fp.write(res.content)
    i += 1

# --END--

完成后，在自己的问价根目录下面找images文件夹，打开文件夹就能看到自己下载的图片啦。

# 下载视频
# 安装第三方模块进行下载
import requests

# 下载图片
url_list = [
    r"https://v3-web.douyinvod.com/5f859c5bcc8097014fe28d4aa0a51c85/65da090c/video/tos/cn/tos-cn-ve-15/oMGs"
    r"fhDALWBH8UmrCmFEAeDhBqA7L14IQBfmE6/?a=6383&ch=5&cr=3&dr=0&lr=all&cd=0%7C0%7C0%7C3&cv=1&br=1721&bt="
    r"1721&cs=0&ds=6&ft=bvTKJbQQqUnXfmoZmo0ORVTYA0pikecsejKJV7TYeo0P3-I&mime_type=video_mp4&qs=0&rc=OGY1Oz"
    r"VmNWQ5aTU4OWY1OEBpM2RnO205cjt3cTMzNGkzM0AzMy1iMzA1XmMxYjAxNmA1YSMtM24tMmRjY15gLS1kLS9zcw%3D%3D&btag"
    r"=e00028000&dy_q=1708784219&feature_id=f0150a16a324336cda5d6dd0b69ed299&l=20240224221658C1E7B1B597C2"
    r"A7D01ABA",

    "https://v3-web.douyinvod.com/f3e00fdf66b9fa32014f76739ce9a6c2/65da0964/video/tos/cn/tos-cn-ve-15"
    r"/ocw45QDzyBEJirkfhQCGnAIsAA7ZN7MgAeE5LX/?a=6383&ch=5&cr=3&dr=0&lr=all&cd=0%7C0%7C0%7C3&cv=1&br="
    r"817&bt=817&cs=0&ds=6&ft=bvTKJbQQqUnXfmoZmo0ORVTYA0pi9vcsejKJV7TYeo0P3-I&mime_type=video_mp4&qs="
    r"0&rc=N2U2OGc0OGhkZWZmaGlnOUBpMzVoMzw6ZmVncTMzNGkzM0AxMjBjMzUzXzUxMDQuNi5gYSNsNjRqcjRnbGBgLS1kLT"
    r"Bzcw%3D%3D&btag=e00028000&dy_q=1708784308&feature_id=f0150a16a324336cda5d6dd0b69ed299&l=20240224"
    r"221827BDAEFE7D705F16E75C4C",
]
headers = {
    "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) "
                  "Chrome/99.0.4844.84 Safari/537.36 HBPC/12.1.3.306"
}
i = 0
for item in url_list:
    # 下载文件
    res = requests.get(
        url=item,
        headers=headers
    )
    # 保存文件

    with open("./videos/video" + str(i) + ".mp4", "wb") as fp:
        print("downloading", i)
        fp.write(res.content)
    i += 1

好吧，可能是下载视频的格式问题，我的视频下载下来无法播放，下载的时候要注意，看好文件格式是什么。

接下来，把下载的相关代码拼接到相关函数就OK了。参考如下，我只写了下载图片的代码，其他的类似，只要模仿images区域的函数，将download函数放置到正确的地方即可。

print("correct index, downloading image ...")
# print(img_data[img_num][0], " ", img_data[img_num][1])
title, url = item_tuple
download(model=".png", url=url, file_name=title)
print(title, url)
print("download image over.")

import sys

import requests

# 图片专区
img_data = {
    "1": ("image1", r"https://pic.3gbizhi.com/uploadmark/20230825/979bcabfd305afce4b5b5d00e467e01f.jpg"),
    "2": ("image2", r"https://pic.3gbizhi.com/uploadmark/20220916/35c9f1a1e642ba133b0efc2b58b9ae02.png"),
    "3": ("image3", r"https://pic.3gbizhi.com/uploadmark/20190912/6d7abd46d1531635e9b187cdea724345.jpg"),
    "4": ("image4", r"https://pic.3gbizhi.com/uploadmark/20231120/004a59dc1b775ee4ea19cb9f350682bc.jpg"),
    "5": ("image5", r"https://pic.3gbizhi.com/uploadmark/20231030/d74c8cbc8bb461cef094e6b686990fde.jpg"),
    "6": ("image6", r"https://pic.netbian.com/uploads/allimg/230405/000245-168062416593ad.jpg")
}

# NBA 专区
nba_data = {
    "1": {
        "title": "title1",
        "url": r"https://v3-web.douyinvod.com/5f859c5bcc8097014fe28d4aa0a51c85/65da090c/video/tos/cn/tos-cn-ve-15/oMGs"
               r"fhDALWBH8UmrCmFEAeDhBqA7L14IQBfmE6/?a=6383&ch=5&cr=3&dr=0&lr=all&cd=0%7C0%7C0%7C3&cv=1&br=1721&bt="
               r"1721&cs=0&ds=6&ft=bvTKJbQQqUnXfmoZmo0ORVTYA0pikecsejKJV7TYeo0P3-I&mime_type=video_mp4&qs=0&rc=OGY1Oz"
               r"VmNWQ5aTU4OWY1OEBpM2RnO205cjt3cTMzNGkzM0AzMy1iMzA1XmMxYjAxNmA1YSMtM24tMmRjY15gLS1kLS9zcw%3D%3D&btag"
               r"=e00028000&dy_q=1708784219&feature_id=f0150a16a324336cda5d6dd0b69ed299&l=20240224221658C1E7B1B597C2"
               r"A7D01ABA"},
    "2": {
        "title": "title2",
        "url": r"https://v3-web.douyinvod.com/f3e00fdf66b9fa32014f76739ce9a6c2/65da0964/video/tos/cn/tos-cn-ve-15"
               r"/ocw45QDzyBEJirkfhQCGnAIsAA7ZN7MgAeE5LX/?a=6383&ch=5&cr=3&dr=0&lr=all&cd=0%7C0%7C0%7C3&cv=1&br="
               r"817&bt=817&cs=0&ds=6&ft=bvTKJbQQqUnXfmoZmo0ORVTYA0pi9vcsejKJV7TYeo0P3-I&mime_type=video_mp4&qs="
               r"0&rc=N2U2OGc0OGhkZWZmaGlnOUBpMzVoMzw6ZmVncTMzNGkzM0AxMjBjMzUzXzUxMDQuNi5gYSNsNjRqcjRnbGBgLS1kLT"
               r"Bzcw%3D%3D&btag=e00028000&dy_q=1708784308&feature_id=f0150a16a324336cda5d6dd0b69ed299&l=20240224"
               r"221827BDAEFE7D705F16E75C4C"}}

# 短视频专区
short_video_data = {
    "1": {
        "title": "title1",
        "url": r"https://v3-web.douyinvod.com/5f859c5bcc8097014fe28d4aa0a51c85/65da090c/video/tos/cn/tos-cn-ve-15"
               r"/oMGsfhDALWBH8UmrCmFEAeDhBqA7L14IQBfmE6/?a=6383&ch=5&cr=3&dr=0&lr=all&cd=0%7C0%7C0%7C3&cv=1&br="
               r"1721&bt=1721&cs=0&ds=6&ft=bvTKJbQQqUnXfmoZmo0ORVTYA0pikecsejKJV7TYeo0P3-I&mime_type=video_mp4&qs"
               r"=0&rc=OGY1OzVmNWQ5aTU4OWY1OEBpM2RnO205cjt3cTMzNGkzM0AzMy1iMzA1XmMxYjAxNmA1YSMtM24tMmRjY15gLS1kL"
               r"S9zcw%3D%3D&btag=e00028000&dy_q=1708784219&feature_id=f0150a16a324336cda5d6dd0b69ed299&l=202402"
               r"24221658C1E7B1B597C2A7D01ABA"
    },
    "2": {
        "title": "title2",
        "url": r"https://v3-web.douyinvod.com/f3e00fdf66b9fa32014f76739ce9a6c2/65da0964/video/tos/cn/tos-cn-ve"
               r"-15/ocw45QDzyBEJirkfhQCGnAIsAA7ZN7MgAeE5LX/?a=6383&ch=5&cr=3&dr=0&lr=all&cd=0%7C0%7C0%7C3&cv"
               r"=1&br=817&bt=817&cs=0&ds=6&ft=bvTKJbQQqUnXfmoZmo0ORVTYA0pi9vcsejKJV7TYeo0P3-I&mime_type=video"
               r"_mp4&qs=0&rc=N2U2OGc0OGhkZWZmaGlnOUBpMzVoMzw6ZmVncTMzNGkzM0AxMjBjMzUzXzUxMDQuNi5gYSNsNjRqcjRnb"
               r"GBgLS1kLTBzcw%3D%3D&btag=e00028000&dy_q=1708784308&feature_id=f0150a16a324336cda5d6dd0b69ed29"
               r"9&l=20240224221827BDAEFE7D705F16E75C4C"
    }
}

def image_area():
    print("======================== you are now in image area ========================")
    msg_list = []
    for k, item in img_data.items():
        string = "{}-{}".format(k, item[0])
        msg_list.append(string)
    msg_string = ": ".join(msg_list)
    while True:
        print(msg_string)
        img_num = input("choose the number of images!\n>>> ")
        if img_num.upper() == "N":
            return
        item_tuple = img_data.get(img_num)

        if not item_tuple:
            print("index error, please try again.", file=sys.stderr)
            continue
        print("correct index, downloading image ...")
        # print(img_data[img_num][0], " ", img_data[img_num][1])
        title, url = item_tuple
        download(model=".png", url=url, file_name=title)
        print(title, url)
        print("download image over.")

        # print("if you want to download the image again? If you want, input n/N else input y/Y.")
        # if_repeat = input(">>> ")
        # if if_repeat.upper() == "Y":
        #     image_area()
        # elif if_repeat.upper() == "N":
        #     print()
        #     return
        # else:
        #     raise ValueError("input error: {}".format(if_repeat))
        # print()

def nba_area():
    img_num = input("choose the number of nba images!\n>>> ")

    print("download image ...")
    print(nba_data[img_num]["title"], " ", nba_data[img_num]["url"])
    print("download image over.")

    print("if you want to download the image again? If you want, input n/N else input y/Y.")
    if_repeat = input(">>> ")
    if if_repeat.upper() == "Y":
        nba_area()
    elif if_repeat.upper() == "N":
        print()
        return
    else:
        raise ValueError("input error: {}".format(if_repeat))
    print()

def video_area():
    img_num = input("choose the number of video!\n>>> ")

    print("download image ...")
    print(short_video_data[img_num]["title"],
          " ", short_video_data[img_num]["url"])
    print("download image over.")

    print("if you want to download the image again? If you want, input n/N else input y/Y.")
    if_repeat = input("please input your choice: \n>>> ")
    if if_repeat.upper() == "Y":
        nba_area()
    elif if_repeat.upper() == "N":
        print()
        return
    else:
        raise ValueError("input error: {}".format(if_repeat))
    print()

def download(model=".jpg", url="", file_name=r""):
    """

    Args:
        url (): str
        model (): range from [".jpg", ".mp4"]

    Returns:

    """
    headers = {
        "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) "
                      "Chrome/99.0.4844.84 Safari/537.36 HBPC/12.1.3.306"
    }
    res = requests.get(
        url=url,
        headers=headers
    )
    # 保存文件

    with open("./download_files/" + file_name + model, "wb") as fp:
        print("downloading...")
        fp.write(res.content)

def run():
    function_dict = {
        "1": image_area,
        "2": nba_area,
        "3": video_area,
    }

    while True:
        print("1. image 2. nba 3. short video")
        choice = input("choose a number, input Q or q to exit.\n>>> ")
        if choice.upper() == "Q":
            break

        func_obj = function_dict.get(choice)
        if not func_obj:
            # raise ValueError("input error: {}".format(choice))
            print("input error, try again: ", file=sys.stderr)
            continue
        func_obj()
    print()

if __name__ == "__main__":
    run()

# --END--

2. lambda表达式 —— 匿名函数

在特定的情况下让代码更简洁。

用一行代码定义一个简单的函数。

def func():
    return 123

# func是函数名(变量)
# lambda: 函数体 --- 你写一个123，内部return一个123
func = lambda: 123

res = func
print(res())  # 123

def func(a1, a2):
    return a1 + a2

func = lambda a1, a2: a1 + a2

res = func
print(res(1, 2))  # 3

def func(data_string):
    return data_string.upper()

func = lambda data_string: data_string.upper()

def func(data_list):
    return data_list[0]

func = lambda data_list: data_list[0]

注意：lambda表达式在内部会自动return，return后面生成的是什么，就返回什么。

# 注意：
data_list = [11, 22, 33]

res = data_list.append(44)
print(res)  # None

def func(data_list):
    return data_list.append(44)
res = func([11, 22, 33])
print(res)  # None

func = lambda data_list: data_list.append(44)

value = func([11, 22, 33])
print(value)  # None

3. 函数做参数

def do():
    print("do")

def func(a1, a2):
    print(a1)
    a2()

func(11, do)
# 11
# do

def do():
    print("do")

def func(a1, a2):
    print(a1)
    a2()
    return 123

v1 = func(11, do)
print(v1)
# 11
# do
# None
# 123

注意：一般情况下少用。

4. 内置函数

python内部为我们写好的函数，拿来用就行。

4.1 数值计算(5)

注意：自己写函数的时候，不要用这种变量名哦。

• abs() 绝对值

  data = abs(-10)
  print(data)  # 10
  

• pow() 次方

  data = pow(2, 5)
  print(data)  # 32 (2 ** 5)
  

• sum() 求和

  num_list = [...]
  sum(num_list)
  

• divmod() 求除法得到的商和余数

  a1, a2 = divmod(92, 10)
  print(a1, a2)
  # 9 2
  

• round() 保留小数点后几位 支持四舍五入

  data = round(3.1415926, 2)
  print(data)  # 3.14
  

4.2 第二组(4)

• min()

  data = [1, 2, 3, 4, 5, 6, 7, 8, 9]
  print(min(data))
  

• max()

  data = [1, 2, 3, 4, 5, 6, 7, 8, 9]
  print(max(data))
  

• all() 列表是否所有元素转换为布尔值都是True

  data = [123, 45, 6, "com"]
  print(all(data))  # True
  

  data = [123, 45, 6, "com", 0]
  print(all(data))  # False
  

• any() 只要有转换为True的就为True

4.3 第三组(3)

• bin() 十进制转二进制
• oct() 十进制转八进制
• hex() 十进制转十六进制

练习题

给出一个IP地址，将每一段转换成二进制。

ip = "192.168.11.23"
192   0b11000000
168   0b10101000
11    0b1011
23    0b10111

# 去掉前面的0b， 补足8个bit
# 再次拼接起来
# 再转换成十进制
    num = int("10101101100011000000010000001002", base=2)
    print(num)

# ========================== 我的代码 ==========================
def main() -> int:
    ip_address = "192.168.11.23"
    a, b, c, d = ip_address.split(".")
    data_list = [a, b, c, d]
    bin_dict = []
    for item in data_list:
        bin_dict.append(bin(int(item)))
    bin_without_0b = []
    for item in bin_dict:
        bin_without_0b.append(item.replace("0b", ""))
    final_string = []
    for item in bin_without_0b:
        if len(item) != 8:
            final_string.append("0" * (8 - len(item)) + item)
        else:
            final_string.append(item)
    string = "".join(final_string)
    number = int(string, base=2)
    print(number)
    return 0

if __name__ == "__main__":
    main()

# 老师的
ip = "192.168.11.23"
bin_str_list = []
str_list = ip.split(".")
for item in str_list:
    bin_str = bin(int(item))[2:]
    bin_fill_str = bin_str.zfill(8)
    bin_str_list.append(bin_fill_str)
num = int("".join(bin_str_list), base=2)
print(num)

还得是老师牛逼！！！简洁而又逻辑清晰。

4.4 第四组(2)

编码时unicode编码，将文字和二进制做对应。

计            10101011110100111101               987

• ord()

  v1 = ord("A")
  print(v1)  # 65
  

• chr()

  v2 = chr(65)
  print(v2)  # A
  

动态验证码：

# 随机获取65-90的数字 利用chr转换成字母
import random

# 随机获取65-90的数字 利用chr转换成字母
char_list = []
for i in range(6):
    num = random.randint(65, 90)  # [65, 90]之间的随机数。
    char_list.append(chr(num))
print("".join(char_list))

4.5 第五组(9)

• int()
• str()
• bool()
• list()
• dict()
• set()
• tuple()
• float()
• bytes()

4.6 第六组(10)

• len()

• print()

• input()

• open()

• range()

• hash() 字典的键，集合元素都必须是可哈希的

• type() 查看数据类型

  def func():
      if type(data) == str:
          ...
      if type(data) == list:
          ...
      ...
  func()
  

  # 建议使用以下的方式:
  def func(data):
      if isinstance(data, str):
          print("string")
      elif isinstance(data, list):
          print("list")
      else:
          return
  

• callable() 判断是否可执行

  age = 12
  
  def func():
      return 123
  
  v1 = callable(age)
  v2 = callable(func)
  
  print(v1, v2)
  

• enumerate() 在循环过程中，自动自增的一列。

  goods = ["computer", "huawei", "xiaomi", "oppo"]
  # 以前
  for i in range(len(goods)):
      msg = "{} {}".format(i + 1, goods[i])
      print(msg)
  
  # 现在
  goods = ["computer", "huawei", "xiaomi", "oppo"]
  for index, item in enumerate(goods, 1):  # 那个1表示起始值
      msg = "{} {}".format(index, item)
  

• sorted() 排序 --不修改源数据 会生成一个新列表

  # 列表中的sort()排序(对原列表进行排序) —— 会修改原列表
  data_list = [15, 25, 0, 13, 2]
  data_list.sort()
  print(data_list)
  

  data_list = [15, 25, 0, 13, 2]
  new_data = sorted(data_list)
  

  注意：如果元素是中文，怎么排序？

  data_list = ["1", "2", "3", "10", "12"]
  new_data = sorted(data_list)
  print(new_data)  # 根据unicode编码排序 -- 因为是字符串！！！
  

  data_list = ["1 哈哈好", "2 嗯嗯", "3 哈哈哈", "10 嗯嗯呢", "12 哈哈好"]
  # 自定义排序规则 函数返回什么 那就按照返回的值进行排序
  def func(arg):
      return int(arg.split(" ")[0])
  
  new_data = sorted(data_list, key=func)
  print(new_data)
  

  data_list = ["1 哈哈好", "2 嗯嗯", "3 哈哈哈", "10 嗯嗯呢", "12 哈哈好"]
  func = lambda arg: int(arg.split(" ")[0])
  new_data = sorted(data_list, key=func)
  print(new_data)
  

5. 推导式

python提供的简单的语法，一行代码生成列表、字典等多个元素。

创建一堆数据并存储到列表中

data = []
for i in range(1, 101):
    data.append(i)

5.1 列表推导式

data_list = [i for i in range(100)]
# [0, 1, 2, ... , 99]

data_list = [100 for i in range(100)]
# [100, 100, 100, ... , 100]

data_list = [100 + i for i in range(100)]
# [100, 101, 102, ... , 199]

data_list = [[1, 2] for i in range(100)]
# [[1, 2], [1, 2], [1, 2], ... , [1, 2]]

data_list = [(i, i+100) for i in range(100)]
# [(0, 100), (1, 101), (2, 102), ... , (99, 199)]

data_list = ["工号-{}".format(i) for i in range(100)]
# ['工号-0', '工号-1', '工号-2', ..., '工号-99']

data_list = [i for i in range(10) if i > 6]
# [7, 8, 9]

data_list = [i for i in range(100) if i > 6 and i < 10]
# [7, 8, 9]

案例

data_list = [1, True, "com", "sci", [11, 22], 99, 123, (45,)]
result = [i for i in data_list if isinstance(i, int)]

注意下面两张图：

data_list = [1, True, "com", "sci", [11, 22], 99, 123, (45,)]
result = [i for i in data_list if type(data_list) is int]

5.2 字典推导式

data = {i: 123 for i in range(10)}
"""
{
    0: 123,
    2: 123,
    ...,
    9: 123
}
"""

data = {i: (i, 100) for i in range(10)}
"""
{
	0: (0, 100),
	1: (1, 100),
	2: (2, 100),
	3: (3, 100),
	4: (4, 100),
	5: (5, 100),
	6: (6, 100),
	7: (7, 100),
	8: (8, 100),
	9: (9, 100)
}
"""

data = {i: (i, 100) for i in range(10) if i > 7}
"""
{
	8: (8, 100),
	9: (9, 100)
}
"""

练习题：

text = r"https://www.sogou.com/web?query=xx&_asf=www.sogou.com&_ast=&w=01019900&p=40040100&ie=utf8&from=index-nologin&s_from=index&sut=19&sst0=1708868657212&lkt=0%2C0%2C0&sugsuv=1708868652598249&sugtime=1708868657212"
# 将字符串转换为字典： {"query": xx, "_asf": xxxx, ...}

data_dict = {i.split("=")[0]: i.split("=")[1] for i in text.split("?")[1].split("&")}
"""
{
    '_asf': 'www.sogou.com',
    '_ast': '',
    'from': 'index-nologin',
    'ie': 'utf8',
    'lkt': '0%2C0%2C0',
    'p': '40040100',
    'query': 'xx',
    's_from': 'index',
    'sst0': '1708868657212',
    'sugsuv': '1708868652598249',
    'sugtime': '1708868657212',
    'sut': '19',
    'w': '01019900'
}
"""

a_dict = {
    '_asf': 'www.sogou.com',
    '_ast': '',
    'from': 'index-nologin',
    'ie': 'utf8',
    'lkt': '0%2C0%2C0',
    'p': '40040100',
    'query': 'xx',
    's_from': 'index',
    'sst0': '1708868657212',
    'sugsuv': '1708868652598249',
    'sugtime': '1708868657212',
    'sut': '19',
    'w': '01019900'
}
data_list = ["{}={}".format(k, v) for k, v in a_dict.items()]
print(data_list)
"""
['_asf=www.sogou.com',
 '_ast=',
 'from=index-nologin',
 'ie=utf8',
 'lkt=0%2C0%2C0',
 'p=40040100',
 'query=xx',
 's_from=index',
 'sst0=1708868657212',
 'sugsuv=1708868652598249',
 'sugtime=1708868657212',
 'sut=19',
 'w=01019900']
"""
print("&".join(data_list))

5.3 集合推导式

...

5.4 元组推导式(生成器表达式)

...

上述就是学习函数必备的知识点。

• 定义
• 执行
• 参数
• 返回值
• 作用域
• 函数名就是一个变量名
• lambda表达式
• 内置函数
• 推导式 —— 与函数无关 简化代码

6. 关于pip.exe

6.1 下载第三方包

pip是一个专门用于帮助我们安装第三方库的工具。

- python安装目录
	- python.exe   ---   python解释器
    - Scripts
    	- pip.exe
    - Lib(内置+第三方安装的库)
    	- site-package
        	- 第三方包

>>> pip install 包名称

6.2 pip常见命令

• 安装 pip install 包名称

• 卸载pip uninstall 包名称

• 罗列目前已经安装的第三方包 pip list

• 将已安装的包写到文件中 pip freeze > requirements.txt，还可以用pip install -r requirements.txt进行批量安装 requirements.txt一般都放在项目的根目录下面。(每个项目目录下面都可以放一个。)

  # 这个可以用于工作交接。
  # 逐一安装：
  >>> pip install absl-py==2.1.0
  >>> pip install aiosignal==1.3.1
  
  # 批量安装
  pip install -r requirements.txt
  

• 在同一个python环境中，无法同时安装多个版本的包，只能同时有一个。即：你如果安装了requests2.1，那么你就无法安装另外的requests包。

6.3 配置

# 成为开源作者，发布包：
https://www.bilibili.com/video/BV17541187de

有时候下载时会比较慢，从豆瓣源下载：

# 基于豆瓣源下载：
>>> pip install 包名称 -i https://pypi.douban.com/simple/

# 永久默认配置为豆瓣源
>>> pip config set global.index-url https://pypi.douban.com/simple/
>>> pip install 包名称

• 一般情况下，我们在开发过程总遇到的所有第三方包都可以通过pip包管理工具来进行安装。但是有些包在pip中没有，有可能找到源码包，可以通过源码进行安装。

  • 下载 以requests为例 去https://pypi.org/search/搜索你想要下载的包。

    https://files.pythonhosted.org/packages/9d/be/10918a2eac4ae9f02f6cfe6414b7a155ccd8f7f9d4380d62fd5b955065c3/requests-2.31.0.tar.gz
    

  • 解压
    
    

  • 安装【终端】

    • 进入解压的源码包

      >>> cd C:\Users\20866\Desktop\requests-2.31.0\requests-2.31.0
      

    • 执行安装命令

      >>> python setup.py build
      >>> python setup.py install
      

  • 安装 wheel包
    
    源码开发者提前将代码打包成wheel包，到时候不需要build只需要install即可。

    • pip install wheel

    • 下载wheel包
      
      https://files.pythonhosted.org/packages/70/8e/0e2d847013cb52cd35b38c009bb167a1a26b2ce6cd6965bf26b47bc0bf44/requests-2.31.0-py3-none-any.whl
      
      

    • 进入终端进行安装

      • 打开终端 进入wheel包目录
      • 直接安装
        
        

• 注意事项，无论通过什么方式安装的第三方包，都是安装在site-packages目录下面。卸载直接通过pip uninstall 包名称

写在最后

由于这些笔记都是从typora里面粘贴过来的，导致图片会加载失败，如果想要带图片的笔记的话，我已经上传至github，网址(​​https://github.com/wephiles/python-foundation-note​​​)如果github上不去的话也可以去我的gitee下载，网址(​​https://gitee.com/wephiles/python-django-notes​​)。欢迎大家来下载白嫖哦，最后，如果可爱又善良的你能够给我github点个star，那你将会是这个世界上运气最好的人喔。