Cheat Code Python: Trik Rahasia untuk Mempercepat Proyek Coding

# Auto-aktifkan venv saat masuk folder  
export VENV_DIR=".venv"  
cd() {  
  builtin cd "$@" && [[ -d "$VENV_DIR" ]] && source "$VENV_DIR/bin/activate"  
}  

pip install pipreqs  
pipreqs . --force  # Deteksi dependency berdasarkan import di kode  

hasil = []  
for i in range(10):  
    if i % 2 == 0:  
        hasil.append(i*2)  

hasil = [i*2 for i in range(10) if i % 2 == 0]  

# Ganti if-else bertingkat  
role = "admin" if user.is_superuser else "mod" if user.is_staff else "user"  

# Ambil elemen pertama & terakhir list  
first, *_, last = [1, 2, 3, 4, 5]  # first=1, last=5  

# Swap variabel tanpa temp  
a, b = b, a  

def calculate(x):  
    breakpoint()  # Langsung masuk ke debugger  
    return x * 2  

import re  
re.DEBUG  
match = re.compile(r'^\d{3}-\d{2}$').match("123-45")  

import pandas as pd  

# Filter baris dengan query string  
df.query('salary > 5000 & department == "IT"')  

# Pilih kolom dengan regex  
df.filter(regex='^user_')  # Ambil kolom diawali "user_"  

# Hitung jarak Euclidean antar vektor  
import numpy as np  
vectors = np.random.rand(1000, 3)  
distances = np.sqrt(((vectors[:, None] - vectors) ** 2).sum(axis=2))  

repos:  
- repo: https://github.com/pre-commit/pre-commit-hooks  
  rev: v4.4.0  
  hooks:  
    - id: trailing-whitespace  
    - id: end-of-file-fixer  
    - id: check-yaml  
- repo: https://github.com/psf/black  
  rev: 23.7.0  
  hooks:  
    - id: black  

# Setelah inisialisasi Git  
heroku create -a nama-app  
git push heroku main  

"""  
CHEAT SHEET PYTHON - 2024  
"""  

# ====== LIST OPERATIONS ======  
sum_even = sum(x for x in lst if x % 2 == 0)  # Sum bilangan genap  
flatten = [item for sublist in nested_list for item in sublist]  

# ====== DICTIONARY PRO ======  
from collections import defaultdict  
counter = defaultdict(int)  
counter["a"] += 1  # Tidak perlu cek key exists  

# ====== CONTEXT MANAGER CUSTOM ======  
from contextlib import contextmanager  
@contextmanager  
def timer():  
    import time  
    start = time.time()  
    yield  
    print(f"Waktu: {time.time()-start:.2f} detik")  

# ====== JINJA2 AUTOESCAPE ======  
from markupsafe import escape  
user_input = "<script>alert('hacked!')</script>"  
safe_html = escape(user_input) 

# ========== VARIABEL & TIPE DATA ==========
# Type Hinting (Python 3.10+)
name: str = "Alice"
age: int = 30
coordinates: tuple[float, float] = (3.14, -2.71)

# Walrus Operator (Python 3.8+)
if (n := len(data)) > 10:
    print(f"Data terlalu besar ({n} elemen)")

# ========== STRING ADVANCED ==========
# f-String Formatting
price = 99.9
print(f"Harga: {price:.2f} IDR")  # Harga: 99.90 IDR
print(f"Binary: {42:b}")          # Binary: 101010

# Multiline String dengan Preserved Format
sql = ("""
    SELECT * FROM users
    WHERE age > {age}
    LIMIT 10
""").format(age=18)

# ========== LIST/DIKT PRO ==========
# List Comprehension dengan Kondisi
numbers = [x**2 if x % 2 == 0 else x**3 for x in range(10)]

# Merge Dictionaries (Python 3.9+)
dict1 = {"a": 1, "b": 2}
dict2 = {"b": 3, "c": 4}
merged = dict1 | dict2  # {'a':1, 'b':3, 'c':4}

# ========== FUNGSI & CLASS ==========
# Decorator dengan Parameter
def retry(max_attempts):
    def decorator(func):
        def wrapper(*args, **kwargs):
            for _ in range(max_attempts):
                try:
                    return func(*args, **kwargs)
                except Exception:
                    pass
            raise RuntimeError("Gagal setelah beberapa percobaan")
        return wrapper
    return decorator

# Dataclass (Python 3.10+)
from dataclasses import dataclass

@dataclass(slots=True, frozen=True)
class User:
    name: str
    age: int

# ========== ASYNCIO ==========
# Async/Await Basic Pattern
import asyncio

async def fetch_data(url):
    async with aiohttp.ClientSession() as session:
        async with session.get(url) as response:
            return await response.json()

# Run Parallel Tasks
async def main():
    task1 = asyncio.create_task(fetch_data(url1))
    task2 = asyncio.create_task(fetch_data(url2))
    results = await asyncio.gather(task1, task2)

# ========== PANDAS PRO ==========
# Optimasi DataFrame Besar
import pandas as pd

# Baca file dengan chunks
chunk_size = 10_000
df = pd.concat(chunk for chunk in pd.read_csv('large.csv', chunksize=chunk_size))

# Query Efisien dengan .eval()
df.eval("revenue = price * quantity", inplace=True)

# ========== ERROR HANDLING ==========
# Custom Exception
class APITimeoutError(Exception):
    def __init__(self, endpoint):
        super().__init__(f"Timeout mengakses {endpoint}")
        self.endpoint = endpoint

# Context Manager untuk Error Handling
from contextlib import contextmanager

@contextmanager
def handle_errors():
    try:
        yield
    except ValueError as ve:
        print(f"Error nilai: {ve}")
    except Exception as e:
        print(f"Error tak terduga: {e}")

# ========== DEBUGGING ==========
# Debugging dengan breakpoint()
def buggy_function():
    breakpoint()  # Masuk ke pdb++
    # Perintah berguna: 
    # n (next), s (step into), pp (pretty print), w (where)

# Profiling dengan cProfile
import cProfile
cProfile.run('my_function()', sort='cumtime')

# ========== OPTIMISASI ==========
# Memoization dengan lru_cache
from functools import lru_cache

@lru_cache(maxsize=128)
def fibonacci(n):
    if n < 2:
        return n
    return fibonacci(n-1) + fibonacci(n-2)

# Kompilasi JIT dengan Numba
from numba import njit

@njit
def monte_carlo_pi(n_samples):
    acc = 0
    for _ in range(n_samples):
        x = np.random.random()
        y = np.random.random()
        if (x**2 + y**2) < 1.0:
            acc += 1
    return 4.0 * acc / n_samples

# ========== TESTING ==========
# Unit Test dengan pytest
def test_addition():
    assert 1 + 1 == 2

# Mocking dengan pytest-mock
def test_api_call(mocker):
    mock_get = mocker.patch('requests.get')
    mock_get.return_value.json.return_value = {"status": "OK"}
    
    result = fetch_data("http://fakeapi.com")
    assert result["status"] == "OK"

# ========== DEPLOYMENT ==========
# Dockerfile Minimal Python
"""
FROM python:3.11-slim
WORKDIR /app
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt
COPY . .
CMD ["gunicorn", "app:app", "-b", "0.0.0.0:8000"]
"""

# ========== GIT HOOKS ==========
# .pre-commit-config.yaml
"""
repos:
- repo: https://github.com/pre-commit/pre-commit-hooks
  rev: v4.4.0
  hooks:
    - id: trailing-whitespace
    - id: end-of-file-fixer
    - id: check-yaml
- repo: https://github.com/psf/black
  rev: 23.7.0
  hooks:
    - id: black
      args: [--line-length=88]
"""

# ========== KEAMANAN ==========
# Hash Password dengan Bcrypt
import bcrypt

salt = bcrypt.gensalt()
hashed = bcrypt.hashpw(b"password123", salt)

# Validasi Input dengan Pydantic
from pydantic import BaseModel, EmailStr

class UserInput(BaseModel):
    name: str
    email: EmailStr
    age: int = Field(gt=0, lt=120)