Beta系数计算

def solve(stock_returns, market_returns):
    n = len(stock_returns)
    mean_stock = sum(stock_returns) / n
    mean_market = sum(market_returns) / n
    cov = sum((s - mean_stock) * (m - mean_market) for s, m in zip(stock_returns, market_returns)) / n
    var_market = sum((m - mean_market) ** 2 for m in market_returns) / n
    beta = cov / var_market
    return {"协方差": round(cov, 6), "市场方差": round(var_market, 6), "Beta": round(beta, 4)}