当LPR利率来临的时候，我们的房贷该不该改？

根据中国人民银行公告，存量浮动利率贷款定价基准转换自2020年3月1日如期启动。根据规定，存量浮动利率房贷的贷款人，重签合同时可以选择固定利率也可以选择贷款市场报价利率(LPR)的浮动利率。定价基准只能转换一次，转换之后不能再次转换。注意，这里的意思应该是LPR的bp值只能改一次，而不是LPR的数值不能改。

　　那么，买房、有房贷的小伙伴们该如何选择？对此，专家表示，监管层明确要继续推进LPR改革，引导整体市场利率和贷款利率下行，LPR或许是更好的选择。此外，换锚将推进利率市场化“两轨并一轨”，先增量、后存量渐进式改革，有效保障贷款合约基准的平稳转换，为实体经济降成本打开新空间。

但是，专家靠谱吗？我想大部分人应该是从来没有成功薅过社会主义羊毛的。所以，我们自己写程序，判断下到底该不该换成LPR。以下是源代码。兄弟姐妹们自己跑一下，心里就有底了。

# -*- coding: utf-8 -*-
# @Time    : 20/2/27 11:14
# @Author  : Jay Lam
# @File    : LPR_Calculator.py
# @Software: PyCharm


import math
import random

import numpy as np


# LPR计算
def LPRCalculator():
	currentLPR = round(float(input("输入更改合同时的LPR利率(%)：")), 2)
	currentInterest = round(float(input("输入更改合同时的固定利率(%)：")), 2)
	totalMonth = int(input("输入贷款总月数："))
	residueMonth = int(input("输入剩余贷款月数："))
	paymentPlan = int(input("输入还款方式。等额本金输入0，等额本息输入1："))
	rangeLimit = int(input("输入是否限制未来LPR利率预测。不限制0，减少输入-1，增加输入1："))
	totalLoan = round(float(input("输入贷款总额(元)：")), 2)

	bp = currentInterest - currentLPR  # 基点计算
	changeTimes = math.floor((totalMonth - residueMonth) / 12)  # 一年允许改变一次利率

	if paymentPlan == 0:
		oldTotalPayment = averageCapital(totalLoan, 1, currentInterest, totalMonth)[0]
		oldResidueAmount = oldTotalPayment - averageCapital(totalLoan, 1, currentInterest, totalMonth)[1][
											 0:(totalMonth - residueMonth)].sum()
		print(oldResidueAmount)
		print("LPR和原计划支出总额差为：",
			  round(LPR(changeTimes, bp, rangeLimit, totalLoan, residueMonth, currentLPR)[0] - oldResidueAmount, 2),
			  "元")

	elif paymentPlan == 1:
		oldTotalPayment = averageCapitalPlusInterest(totalLoan, 1, currentInterest, totalMonth)[0]
		oldResidueAmount = averageCapitalPlusInterest(totalLoan, 1, currentInterest, totalMonth)[1]*residueMonth
		print("LPR和原计划支出总额差为：",
			  round(LPR(changeTimes, bp, rangeLimit, totalLoan, residueMonth, currentLPR)[1] - oldResidueAmount, 2),
			  "元")


# 随机预测LPR
def LPR(changeTimes, bp, rangeLimit, totalLoan, resMonth, currentLPR):
	plan0 = []
	plan1 = []
	if rangeLimit == 0:
		for i in range(1, changeTimes):
			actualRatio = random.random() + bp
			currentYearPayment0 = averageCapital(totalLoan, 1, actualRatio, resMonth)[1][0:12].sum()
			currentYearPayment1 = averageCapitalPlusInterest(totalLoan, 1, actualRatio, resMonth)[1] * 12
			# 等额本息法直接每个月乘以12获得年度支出值
			plan0.append(currentYearPayment0)
			plan1.append(currentYearPayment1)
		actualTotalPayment0 = np.array(plan0).sum()
		actualTotalPayment1 = np.array(plan1).sum()
	elif rangeLimit == 1:
		actualRatio = randAscending(changeTimes, currentLPR + 0.15, currentLPR - 0.15)  # 未来变化幅度不超过签约时LPR±0.15
		for i in range(0, len(actualRatio)):
			currentYearPayment0 = averageCapital(totalLoan, 1, actualRatio[i], resMonth)[1][0:12].sum()
			currentYearPayment1 = averageCapitalPlusInterest(totalLoan, 1, actualRatio[i], resMonth)[1] * 12
			plan0.append(currentYearPayment0)
			plan1.append(currentYearPayment1)
		actualTotalPayment0 = np.array(plan0).sum()
		actualTotalPayment1 = np.array(plan1).sum()
	elif rangeLimit == -1:
		actualRatio = randDecending(changeTimes, currentLPR + 0.15, currentLPR - 0.15)
		for i in range(0, len(actualRatio)):
			currentYearPayment0 = averageCapital(totalLoan, 1, actualRatio[i], resMonth)[1][0:12].sum()
			currentYearPayment1 = averageCapitalPlusInterest(totalLoan, 1, actualRatio[i], resMonth)[1] * 12
			plan0.append(currentYearPayment0)
			plan1.append(currentYearPayment1)
		actualTotalPayment0 = np.array(plan0).sum()
		actualTotalPayment1 = np.array(plan1).sum()
	return round(actualTotalPayment0, 2), round(actualTotalPayment1, 2)


# 生成升序随机数序列
def randAscending(changetimes, uplimit, lowlimit):
	se = []
	for _ in range(changetimes):
		se.append(round(random.uniform(lowlimit, uplimit), 4))
	se.sort(reverse=False)
	return se


# 生成降序随机数序列
def randDecending(changetimes, uplimit, lowlimit):
	se = []
	for _ in range(changetimes):
		se.append(round(random.uniform(lowlimit, uplimit), 4))
	se.sort(reverse=True)
	return se


# 等额本息法
def averageCapitalPlusInterest(principal, principalRatio, anualInterestRate, month):
	# principal表示房价总额,principalRatio表示房贷百分比,anualInterestRate表示房贷年利率,month表示房贷月份
	mortgage = np.around(principal * principalRatio, 2)  # 计算需要贷款的金额
	monthlyPayment = np.around(mortgage * averageCapitalPlusInterestRate(month, monthlyInterestRate(anualInterestRate)),
							   2)  # 计算每月应还款金额
	totalInt = np.around(totalInterest(mortgage, monthlyPayment, month), 2)
	mortgageIntoTenThousand = np.around(mortgage / 10000, 2)  # 将贷款总金额转化为万元
	print("贷款:", mortgageIntoTenThousand, "万元")  # 输出结果
	print("年利率:", anualInterestRate, "%")
	print("按揭月数:", month, "月")
	print("每月应还:", monthlyPayment, "元")  # 输出结果
	print("需付利息:", totalInt, "元")
	totalPayment = np.around(monthlyPayment * month, 2)  # 还款总额
	return totalPayment, monthlyPayment


# 等额本息法计算每月利率
def monthlyInterestRate(anualInterestRate):
	return (anualInterestRate / 12) / 100  # 年利率/12


# 等额本息法计算比例系数
def averageCapitalPlusInterestRate(month, monthlyInterestRate):
	R = monthlyInterestRate
	N = month
	I = R * math.pow(1 + R, N) / (math.pow(1 + R, N) - 1)
	return I


def totalInterest(mortgage, monthlyPayment, month):
	return monthlyPayment * month - mortgage


# 等额本金法
def averageCapital(principal, principalRatio, anualInterestRate, month):
	# principal表示房价总额,principalRatio表示房贷百分比,anualInterestRate表示房贷年利率,month表示房贷月份
	monthlyPayment = np.zeros(month)  # 初始化每月还款金额
	cont = 0
	mortgage = np.around(principal * principalRatio, 2)  # 计算需要贷款的金额
	mortgageIntoTenThousand = np.around(mortgage / 10000, 2)  # 将贷款总金额转化为万元
	print("贷款:", mortgageIntoTenThousand, "万元")  # 输出结果
	print("年利率:", anualInterestRate, "%")
	print("按揭月数:", month, "月")
	for i in range(0, month):
		monthlyPayment[i] = np.around((mortgage / month) + (mortgage * monthlyInterestRate2(anualInterestRate)) - (
				i * (mortgage / month) * monthlyInterestRate(anualInterestRate)), 2)
		# 每月还款金额
		cont += np.around(monthlyPayment[i], 2)

		print("第", i + 1, "月应还款:", monthlyPayment[i], "元")  # 输出结果
	totalPayment = np.around(sum(monthlyPayment), 2)  # 计算还款总额
	print("还款总额:", totalPayment, "元")
	return totalPayment, monthlyPayment


# 等额本金法计算每月利率
def monthlyInterestRate2(anualInterestRate):
	return (anualInterestRate / 12) / 100  # 年利率/12


if __name__ == "__main__":
	#print(LPR(25, 0.833, -1, 2730000, 300, 4.9))
	#print(averageCapitalPlusInterest(2000000,1,4.3,360))
	LPRCalculator()

标签：该不该,LPR,month,print,totalLoan,np,来临,anualInterestRate
来源： https://blog.csdn.net/hitpisces/article/details/104658788