big_num = 123456789012345678901234567890
print(big_num * 2)  # 精確計(jì)算，不會(huì)溢出

print(0.1 + 0.2)  # 輸出0.30000000000000004

from decimal import Decimal
print(Decimal('0.1') + Decimal('0.2'))  # 輸出0.3

def is_close(a, b, rel_tol=1e-09):
    return abs(a - b) <= rel_tol * max(abs(a), abs(b))

z = 3 + 4j
print(z.real, z.imag)  # 3.0 4.0
print(abs(z))  # 復(fù)數(shù)模，輸出5.0

from fractions import Fraction
f = Fraction(3, 4)
print(f * 2)  # 輸出3/2

# 計(jì)算立方
cube = x ** 3  # 推薦
cube = pow(x, 3)  # 不推薦

q, r = divmod(10, 3)  # q=3, r=1

# 檢查奇數(shù)
if x & 1:
    print("奇數(shù)")
    
# 交換兩個(gè)變量
a, b = b, a  # Python風(fēng)格
# 或使用位運(yùn)算（僅適用于整數(shù)）
a ^= b
b ^= a
a ^= b

import math
 
# 常用函數(shù)
math.sqrt(x)      # 平方根
math.log(x, base) # 對(duì)數(shù)
math.factorial(n) # 階乘
math.gcd(a, b)    # 最大公約數(shù)（Python 3.5+）
 
# 三角函數(shù)（參數(shù)為弧度）
math.sin(math.pi/2)  # 1.0
 
# 特殊常量
math.pi  # π
math.e   # 自然對(duì)數(shù)底數(shù)

def distance(x1, y1, x2, y2):
    dx = x2 - x1
    dy = y2 - y1
    return math.sqrt(dx*dx + dy*dy)

import random
 
random.random()      # [0.0, 1.0)之間的隨機(jī)浮點(diǎn)數(shù)
random.randint(1, 10) # [1, 10]之間的隨機(jī)整數(shù)
random.choice(['a', 'b', 'c'])  # 隨機(jī)選擇元素
random.shuffle(lst)  # 原地打亂列表順序

pi = 3.1415926
print(f"π的近似值為{pi:.2f}")  # 輸出：π的近似值為3.14

print("{:.3f}".format(123.456789))  # 輸出123.457

# 使用locale模塊（依賴系統(tǒng)設(shè)置）
import locale
locale.setlocale(locale.LC_ALL, 'en_US.UTF-8')
print(locale.format_string("%d", 1234567, grouping=True))  # 輸出1,234,567
 
# 或手動(dòng)實(shí)現(xiàn)
def format_number(n):
    s = str(n)
    if len(s) <= 3:
        return s
    return format_number(s[:-3]) + ',' + s[-3:]

def format_currency(amount, currency='￥'):
    return f"{currency}{amount:,.2f}"
 
print(format_currency(1234567.89))  # 輸出￥1,234,567.89

import re
 
text = "訂單號(hào)12345，金額￥678.90，數(shù)量3件"
numbers = re.findall(r'\d+.?\d*', text)
print(numbers)  # ['12345', '678.90', '3']
 
# 轉(zhuǎn)換為合適類型
result = []
for num in numbers:
    if '.' in num:
        result.append(float(num))
    else:
        result.append(int(num))

def calculate_roi(initial, returns, years):
    """
    計(jì)算年化回報(bào)率
    :param initial: 初始投資
    :param returns: 最終金額
    :param years: 投資年限
    :return: 年化回報(bào)率百分比
    """
    roi = (returns / initial) ** (1/years) - 1
    return round(roi * 100, 2)
 
print(calculate_roi(10000, 15000, 3))  # 輸出14.47

def caesar_cipher(num, shift):
    """簡(jiǎn)單的數(shù)字位移加密"""
    num_str = str(num)
    encrypted = []
    for digit in num_str:
        encrypted_digit = (int(digit) + shift) % 10
        encrypted.append(str(encrypted_digit))
    return int(''.join(encrypted))
 
# 加密
encrypted = caesar_cipher(123456, 3)  # 456789
# 解密
decrypted = caesar_cipher(encrypted, -3)  # 123456

# 計(jì)算1到1億的和（內(nèi)存高效方式）
def sum_large_numbers():
    return sum(i for i in range(1, 100_000_001))

import numpy as np
 
# 創(chuàng)建100萬(wàn)個(gè)隨機(jī)數(shù)
arr = np.random.rand(1_000_000)
 
# 向量化運(yùn)算比循環(huán)快100倍以上
squared = arr ** 2  # 瞬間完成

# 低效方式
result = []
for i in range(1000):
    result.append(float(i))  # 每次循環(huán)都進(jìn)行類型檢查
 
# 高效方式
result = [float(i) for i in range(1000)]  # 列表推導(dǎo)式更優(yōu)
# 或直接使用map
result = list(map(float, range(1000)))

if 0.1 + 0.2 == 0.3:  # 永遠(yuǎn)不會(huì)為True
    print("Equal")

def float_equal(a, b, epsilon=1e-9):
    return abs(a - b) < epsilon

# 不會(huì)溢出，可以放心計(jì)算
x = 10**1000

def safe_divide(a, b):
    try:
        return a / b
    except ZeroDivisionError:
        return float('inf')  # 或返回0或其他默認(rèn)值

pip install numpy pandas scipy sympy