04_data_structures.py

"""
04_data_structures.py
---------------------
Concept: Data Structures (Lists, Dictionaries, Tuples)
Context: Order books, Trade history, and OHLC data.
"""

# 1. Lists (Ordered, Mutable sequence)
# Storing a sequence of executed trade prices
trade_history = [59000, 59200, 58800, 60100]

print("--- Lists: Trade History ---")
print(f"All trades: {trade_history}")
trade_history.append(60500) # New trade executed
print(f"Added new trade: {trade_history}")
print(f"First trade: {trade_history[0]}")
print(f"Last trade: {trade_history[-1]}")


# 2. Dictionaries (Key-Value pairs)
# Representing an Order Book or a specific Coin's metadata
coin_metadata = {
    "symbol": "ETH/USDT",
    "exchange": "Binance",
    "min_qty": 0.001,
    "price_precision": 2
}

print("\n--- Dictionaries: Coin Metadata ---")
print(f"Trading Pair: {coin_metadata['symbol']}")
print(f"Exchange: {coin_metadata['exchange']}")

# Simulating an Order Book
order_book = {
    "bids": [{"price": 2990, "qty": 1.5}, {"price": 2985, "qty": 2.0}],
    "asks": [{"price": 3005, "qty": 0.5}, {"price": 3010, "qty": 1.2}]
}

best_bid = order_book["bids"][0] # First element of the list of bids
print(f"Best Bid: Price ${best_bid['price']}, Qty {best_bid['qty']}")


# 3. Tuples (Ordered, Immutable sequence)
# OHLC (Open, High, Low, Close) data for a single candle
# We use tuples because historical candle data shouldn't change once closed.
# Format: (Open, High, Low, Close)
candle_1h = (3000, 3100, 2950, 3050)

print("\n--- Tuples: OHLC Data ---")
print(f"Open: {candle_1h[0]}")
print(f"Close: {candle_1h[3]}")

# Trying to change a tuple will cause an error:
# candle_1h[0] = 3050  # This would raise TypeError
print("Tuples are immutable (cannot be changed), safe for historical data.")