Python3 标准librarytutorial

import os

# 获取当 before 工作Table of Contents
print(f"当 before 工作Table of Contents: {os.getcwd()}")

# 改变当 before 工作Table of Contents
# os.chdir("/path/to/directory")

# 列出Table of Contents in 容
print("\nTable of Contents in 容:")
for item in os.listdir("."):
    print(f"- {item}")

# creationTable of Contents
if not os.path.exists("test_dir"):
    os.mkdir("test_dir")
    print("\ncreationTable of Contents 'test_dir' 成功")

# checkpath
print("\npathcheck:")
print(f"'test_dir'  is 否存 in : {os.path.exists('test_dir')}")
print(f"'test_dir'  is 否 for Table of Contents: {os.path.isdir('test_dir')}")
print(f"'example.txt'  is 否 for file: {os.path.isfile('example.txt')}")

# 获取environmentvariable
print("\nenvironmentvariable:")
print(f"HOME: {os.environ.get('HOME', 'Not found')}")
print(f"PATH: {os.environ.get('PATH', 'Not found')[:100]}...")

# 执行systemcommands
print("\n执行systemcommands:")
os.system("echo Hello from os.system")

# usingsubprocessmodule执行commands (推荐) 
import subprocess
print("\nusingsubprocess执行commands:")
result = subprocess.run(["echo", "Hello from subprocess"], capture_output=True, text=True)
print(f"commands输出: {result.stdout.strip()}")

import sys

# commands行parameter
print(f"commands行parameter: {sys.argv}")

# Pythonversion
print(f"Pythonversion: {sys.version}")

# module搜索path
print("\nmodule搜索path:")
for path in sys.path:
    print(f"- {path}")

# 标准输入输出
print("\n标准输出example")
sys.stdout.write("这 is throughsys.stdout写入 输出\n")

# 退出程序
# sys.exit(0)  # 0表示正常退出, 非0表示error退出

# 获取平台information
print(f"\n平台information: {sys.platform}")

# 获取最 big 整数
print(f"最 big 整数: {sys.maxsize}")

from datetime import datetime, date, time, timedelta

# 获取当 before 日期 and 时间
now = datetime.now()
print(f"当 before 日期 and 时间: {now}")
print(f"年: {now.year}")
print(f"月: {now.month}")
print(f"日: {now.day}")
print(f"时: {now.hour}")
print(f"分: {now.minute}")
print(f"秒: {now.second}")
print(f"微秒: {now.microsecond}")

# creation日期object
d = date(2023, 12, 25)
print(f"\ncreation 日期: {d}")

# creation时间object
t = time(10, 30, 45)
print(f"creation 时间: {t}")

# creation日期时间object
dt = datetime(2023, 12, 25, 10, 30, 45)
print(f"creation 日期时间: {dt}")

# 日期时间format
print("\n日期时间format:")
print(f"YYYY-MM-DD HH:MM:SS: {dt.strftime('%Y-%m-%d %H:%M:%S')}")
print(f"MM/DD/YYYY: {dt.strftime('%m/%d/%Y')}")
print(f"HH:MM AM/PM: {dt.strftime('%I:%M %p')}")

# 解析string for 日期时间
print("\n解析string for 日期时间:")
date_str = "2023-12-25"
date_obj = datetime.strptime(date_str, "%Y-%m-%d")
print(f"解析结果: {date_obj}")

# 日期时间计算
print("\n日期时间计算:")
today = date.today()
print(f"今天: {today}")
yesterday = today - timedelta(days=1)
print(f"昨天: {yesterday}")
tomorrow = today + timedelta(days=1)
print(f"明天: {tomorrow}")

# 计算两个日期之间 差值
birthday = date(1990, 1, 1)
age = today - birthday
print(f"\n from 1990-01-01 to 今天 天数: {age.days}")
print(f" from 1990-01-01 to 今天 年数: {age.days // 365}")

import time

# 获取当 before 时间戳 ( from 1970年1月1日开始 秒数) 
timestamp = time.time()
print(f"当 before 时间戳: {timestamp}")

# 将时间戳转换 for 本地时间
local_time = time.localtime(timestamp)
print(f"本地时间: {local_time}")

# format时间
print(f"format时间: {time.strftime('%Y-%m-%d %H:%M:%S', local_time)}")

# latency执行
print("\n开始latency...")
time.sleep(2)  # latency2秒
print("latency结束")

# 测量code执行时间
start_time = time.time()

# 执行一些operation
for i in range(1000000):
    pass

end_time = time.time()
execution_time = end_time - start_time
print(f"\ncode执行时间: {execution_time:.6f} 秒")

import math

# 常量
print(f"π: {math.pi}")
print(f"e: {math.e}")

# basic运算
print(f"\n绝 for 值: {math.fabs(-10.5)}")
print(f"向 on 取整: {math.ceil(3.2)}")
print(f"向 under 取整: {math.floor(3.8)}")
print(f"四舍五入: {round(3.5)}")
print(f"幂运算: {math.pow(2, 3)}")
print(f"平方根: {math.sqrt(16)}")

# 三角function
print("\n三角function:")
print(f"sin(π/2): {math.sin(math.pi/2)}")
print(f"cos(π): {math.cos(math.pi)}")
print(f"tan(π/4): {math.tan(math.pi/4)}")
print(f"弧度转角度: {math.degrees(math.pi/2)}")
print(f"角度转弧度: {math.radians(90)}")

#  for 数function
print("\n for 数function:")
print(f"自然 for 数: {math.log(math.e)}")
print(f"以10 for 底  for 数: {math.log10(100)}")
print(f"以2 for 底  for 数: {math.log2(8)}")

# otherfunction
print("\notherfunction:")
print(f"阶乘: {math.factorial(5)}")
print(f"最 big 公约数: {math.gcd(12, 18)}")
print(f"最 small 公倍数: {math.lcm(12, 18)}")
print(f"双曲正弦: {math.sinh(0)}")
print(f"双曲余弦: {math.cosh(0)}")

import random

# 生成随机浮点数 (0.0 to 1.0之间) 
print(f"随机浮点数: {random.random()}")

# 生成指定范围 in  随机整数
print(f"\n1 to 10之间 随机整数: {random.randint(1, 10)}")
print(f"0 to 9之间 随机整数: {random.randrange(10)}")
print(f"1 to 10之间步 long  for 2 随机整数: {random.randrange(1, 10, 2)}")

# 生成指定范围 in  随机浮点数
print(f"\n1 to 10之间 随机浮点数: {random.uniform(1, 10)}")

# 随机选择
print(f"\n随机选择:")
fruits = ["苹果", "香蕉", "橙子", "葡萄", "草莓"]
print(f" from listin随机选择一个元素: {random.choice(fruits)}")
print(f" from listin随机选择3个元素: {random.sample(fruits, 3)}")

# 打乱序列
print(f"\n打乱序列:")
random.shuffle(fruits)
print(f"打乱 after  list: {fruits}")

# 随机种子
print(f"\n随机种子:")
random.seed(42)  # 设置种子
print(f"设置种子 after  随机数: {random.random()}")
random.seed(42)  # 再次设置相同 种子
print(f"再次设置相同种子 after  随机数: {random.random()}")  # 结果相同

from collections import Counter, defaultdict, OrderedDict, namedtuple, deque

# Counter - 计数器
print("Counter:")
text = "hello world hello python"
word_counts = Counter(text.split())
print(f"单词计数: {word_counts}")
print(f"出现次数最 many  2个单词: {word_counts.most_common(2)}")

# defaultdict - 默认dictionary
print("\ndefaultdict:")
d = defaultdict(int)  # 默认值 for 0
for word in text.split():
    d[word] += 1
print(f"单词计数: {dict(d)}")

# usinglistserving as默认值
d = defaultdict(list)
d["fruits"].append("苹果")
d["fruits"].append("香蕉")
d["vegetables"].append("西红柿")
print(f"默认dictionary (list) : {dict(d)}")

# OrderedDict -  has 序dictionary ( in Python 3.7+in, 普通dictionary也保持插入顺序) 
print("\nOrderedDict:")
od = OrderedDict()
od["a"] = 1
od["b"] = 2
od["c"] = 3
print(f" has 序dictionary: {dict(od)}")

# namedtuple - 命名元组
print("\nnamedtuple:")
Point = namedtuple("Point", ["x", "y"])
p = Point(10, 20)
print(f"命名元组: {p}")
print(f"x坐标: {p.x}")
print(f"y坐标: {p.y}")

# deque - 双端queue
print("\ndeque:")
dq = deque([1, 2, 3, 4, 5])
print(f"初始queue: {list(dq)}")

#  from  right 侧添加元素
dq.append(6)
print(f" right 侧添加 after : {list(dq)}")

#  from  left 侧添加元素
dq.appendleft(0)
print(f" left 侧添加 after : {list(dq)}")

#  from  right 侧移除元素
dq.pop()
print(f" right 侧移除 after : {list(dq)}")

#  from  left 侧移除元素
dq.popleft()
print(f" left 侧移除 after : {list(dq)}")

# 旋转
dq.rotate(1)  # 向 right 旋转1位
print(f"向 right 旋转1位 after : {list(dq)}")
dq.rotate(-1)  # 向 left 旋转1位
print(f"向 left 旋转1位 after : {list(dq)}")

import re

# 匹配string
pattern = r"\d+"  # 匹配一个 or  many 个number
text = "There are 123 apples and 456 oranges."

# search - find第一个匹配
match = re.search(pattern, text)
if match:
    print(f"找 to 匹配: {match.group()}")
    print(f"匹配开始位置: {match.start()}")
    print(f"匹配结束位置: {match.end()}")

# findall - find所 has 匹配
matches = re.findall(pattern, text)
print(f"\n所 has 匹配: {matches}")

# finditer - find所 has 匹配并返回iterators
print("\nusingfinditer:")
for match in re.finditer(pattern, text):
    print(f"匹配: {match.group()}, 位置: {match.span()}")

# split - 根据匹配分割string
print(f"\n根据number分割: {re.split(pattern, text)}")

# sub - replace匹配
print(f"\nreplacenumber for 'NUM': {re.sub(pattern, 'NUM', text)}")

# 更 complex  正则表达式
print("\n更 complex  正则表达式:")
# 匹配邮箱地址
email_pattern = r"[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}"
emails = "Contact Us: admin@example.com, support@test.org"
email_matches = re.findall(email_pattern, emails)
print(f"找 to  邮箱地址: {email_matches}")

# 匹配URL
url_pattern = r"https?://[\w\-]+(\.[\w\-]+)+([\w\-.,@?^=%&:/~+#]*[\w\-@?^=%&/~+#])?"
urls = "访问我们 网站: https://www.example.com  and  http://test.org/path"
url_matches = re.findall(url_pattern, urls)
print(f"找 to  URL: {[match[0] for match in url_matches]}")

import json

# Pythonobject转JSONstring
print("Pythonobject转JSONstring:")
data = {
    "name": "Alice",
    "age": 30,
    "city": "New York",
    "hobbies": ["reading", "traveling", "coding"],
    "is_student": False
}

json_str = json.dumps(data, indent=2, ensure_ascii=False)
print(f"JSONstring: {json_str}")

# JSONstring转Pythonobject
print("\nJSONstring转Pythonobject:")
json_str = '''
{
  "name": "Bob",
  "age": 25,
  "city": "London",
  "hobbies": ["football", "music", "gaming"],
  "is_student": True
}
'''

python_obj = json.loads(json_str)
print(f"Pythonobject: {python_obj}")
print(f"姓名: {python_obj['name']}")
print(f"年龄: {python_obj['age']}")
print(f"爱 good : {python_obj['hobbies']}")

# 读写JSONfile
print("\n读写JSONfile:")
# 写入JSONfile
with open("data.json", "w", encoding="utf-8") as f:
    json.dump(data, f, indent=2, ensure_ascii=False)
print("写入JSONfile成功")

# 读取JSONfile
with open("data.json", "r", encoding="utf-8") as f:
    loaded_data = json.load(f)
print(f" from file读取 data: {loaded_data}")

import csv

# 写入CSVfile
print("写入CSVfile:")
data = [
    ["姓名", "年龄", "城市"],
    ["Alice", 30, "New York"],
    ["Bob", 25, "London"],
    ["Charlie", 35, "Paris"]
]

with open("data.csv", "w", newline="", encoding="utf-8") as f:
    writer = csv.writer(f)
    writer.writerows(data)
print("写入CSVfile成功")

# 读取CSVfile
print("\n读取CSVfile:")
with open("data.csv", "r", newline="", encoding="utf-8") as f:
    reader = csv.reader(f)
    for row in reader:
        print(row)

# usingDictWriter and DictReader
print("\nusingDictWriter and DictReader:")
fieldnames = ["姓名", "年龄", "城市"]
dict_data = [
    {"姓名": "David", "年龄": 40, "城市": "Tokyo"},
    {"姓名": "Eve", "年龄": 28, "城市": "Sydney"}
]

# 写入
with open("dict_data.csv", "w", newline="", encoding="utf-8") as f:
    writer = csv.DictWriter(f, fieldnames=fieldnames)
    writer.writeheader()
    writer.writerows(dict_data)
print("写入Dict CSVfile成功")

# 读取
print("\n读取Dict CSVfile:")
with open("dict_data.csv", "r", newline="", encoding="utf-8") as f:
    reader = csv.DictReader(f)
    for row in reader:
        print(row)
        print(f"姓名: {row['姓名']}, 年龄: {row['年龄']}, 城市: {row['城市']}")