问题描述
我正在使用 cvxpy 来解决一个投资组合优化问题,并限制了要考虑的最大资产数量。
为了做到这一点,我想引入新的布尔变量“yi”,如果资产 i
包含在投资组合中,则它们等于 1,否则等于 0。
“yi”变量的总和将等于“k”,这是我要考虑的资产数量。
import numpy as np
import pandas as pd
from cvxpy import *
# assets names
tickers = ["AAA","BBB","CCC","DDD","EEE","FFF"]
# return matrix
ret = pd.DataFrame(np.random.rand(1,6),columns = tickers)
# Variance_Coviariance matrix
covm = pd.DataFrame(np.random.rand(6,columns = tickers,index = tickers)
# problem setting
x = Variable(len(tickers)) # xi variables
y = Variable(len(tickers),boolean = True) # yi variables
er = np.asarray(ret.T) * x # expected return
min_ret = 0.2 # minimum return
risk = quad_form(x,np.asmatrix(covm)) # risk
k = 3 #maximum number of assets to include
constraints = [sum(x) == 1,er >= min_ret,x >= 0,sum(y) == k] #constraints array
for i in range(len(tickers):
constraints.append(x[i] <= y[i]) # additional constraint for which each xi must be less or equal to each yi
objective = Minimize(risk) # set the objective function
prob = Problem(objective,constraints) # set problem
prob.solve() # solve problem
我收到以下错误:
Either candidate conic solvers (['GLPK_MI']) do not support the cones output by the problem (SOC,NonNeg,Zero),or there are not enough constraints in the problem.
我不确定我做错了什么。
解决方法
暂无找到可以解决该程序问题的有效方法,小编努力寻找整理中!
如果你已经找到好的解决方法,欢迎将解决方案带上本链接一起发送给小编。
小编邮箱:dio#foxmail.com (将#修改为@)