灰色预测模型R代码

附录：经典灰色预测模型代码：

x<-c(4643,5853,6876,7847,8724,9425,11045)

x1=NULL

for (i in1:length(x))

{

x1[i]= sum(x[1:i])

}

x2= NULL

for (i in1:(length(x)-1))

{

x2[i]=(x1[i]+x1[i+1])/2

}

y<-x[-1]

z<-x2

lm2= lm(y~z)

a<--(coef(lm2)[2])

b<-coef(lm2)[1]

c= b/a

x;x1;x2;lm2

x5= NULL

x5[1]<-x[1]

for (i in 1:11)#现在是预测五期的，可以改数字

{

x5[i+1]=(x[1]-c)*exp(-a*i)+c

}

x6=NULL

x6<-x5[1]

for (i in1:length(x5))

{

x6[i+1]=x5[i+1]-x5[i]

}

mape=sum(abs((x-x6[1:length(x)])/x))/length(x)

x6;mape

x7<-abs(x6[1:length(x)]-x)

r<-(min(x7)+0.5*max(x7))/(x7+0.5*max(x7))

r1=sum(r)/length(x)

x0=sum(x)/length(x)

s1=sqrt(sum((x-x0)^2)/(length(x)-1))

x70=sum(x7)/length