编写一个函数，用于计算每月的抵押贷款和未偿贷款余额

编写一个函数来计算每月的抵押贷款和未偿贷款余额，通常会涉及月供、剩余还款期限以及当前的本金余额。这里是一个简单的例子，假设月供是固定的，并且每次还款都会减少本金。你可以创建一个名为`calculate_monthly_balance`的函数：

def calculate_monthly_balance(monthly_payment, initial_principal, interest_rate, loan_term_years):
    # 将年利率转换为月利率
    monthly_interest_rate = interest_rate / 12

    # 转换贷款年限为月数
    loan_term_months = loan_term_years * 12

    # 初始化未偿贷款余额和总付款次数
    unpaid_balance = initial_principal
    total_payments = 0

    # 循环直到贷款期满
    while unpaid_balance > 0:
        # 计算本月应还利息
        interest = unpaid_balance * monthly_interest_rate

        # 扣除月供
        remaining_monthly_payment = min(monthly_payment, unpaid_balance)

        # 更新未偿贷款余额
        unpaid_balance -= remaining_monthly_payment - interest

        # 每月增加一次支付计数
        total_payments += 1

    return unpaid_balance, total_payments, unpaid_balance if unpaid_balance > 0 else "已还清"

# 示例使用
monthly_payment = 2000
initial_principal = 300000
interest_rate = 0.04  # 4%
loan_term_years = 20
unpaid_balance, total_payments, final_status = calculate_monthly_balance(monthly_payment, initial_principal, interest_rate, loan_term_years)
print(f"每月未偿贷款余额: {unpaid_balance:.2f}")
print(f"总共偿还次数: {total_payments}")
print(f"贷款结束状态: {final_status}")