[R] Stack dataframes into a matrix

[David Winsemius]

> On Jul 27, 2016, at 8:56 AM, Anamika Chaudhuri <canamika at gmail.com> wrote:
> 
> 
> Y<-matrix(1:40,ncol=2)
> Y1<-Y/60 # estimates of p
> 
> #print(Y1)
> 
> sigma2<- matrix(c(var(Y1[,1]),cov(Y1[,1],Y1[,2]),cov(Y1[,1],Y1[,2]),var(Y1[,2])),2,2)
> #print(sigma2)
> 
> rho<-sigma2[1,2]/sqrt(sigma2[1,1]*sigma2[2,2])
> #rho
> 
> mean(Y1[,1])
> mean(Y1[,2])
> 
> #within<-matrix(data=0,nrow=20,ncol=1)
> 
> for (rate3 in 1:20){
> 
> rate<-Y1[i,]
> #print(rate)
> 
> 
> rate1<-rate/(1-rate)
> 
> 
> rate2<-log(rate1)
> 
> 
> Sigma11<-(1/(rate[1]*(1-rate[1]))^2)*sigma2[1,1]
> Sigma22<-(1/(rate[2]*(1-rate[2]))^2)*sigma2[2,2]
> Sigma12<-(1/((rate[1]*(1-rate[1]))*(rate[2]*(1-rate[2]))))*sigma2[1,2]
> 
> Sigma2<-matrix(c(Sigma11,Sigma12,Sigma12,Sigma22),2,2)
> #print(Sigma2)
> 
> rate3<-mvrnorm(1000, mu=c(rate2[1],rate2[2]), Sigma2)
> 
> #print(rate3)
> 
> x<-exp(rate3[,1])/(1+exp(rate3[,1]))
> y<-exp(rate3[,2])/(1+exp(rate3[,2]))
> print(x) # Need to be able to stack the x's to produce one matrix
> }

Not reproducible. 
No loading of package for mvnorm (probably MASS) and suspect that you meant the loop to be over 'i' rather than 'rate3' since Y1[i,] throws an error. If my guesses are correct then perhaps:

require(MASS)
X <- matrix(NA, nrow=20, ncol=1000)  # predimentsion with NA's
Y<-matrix(1:40,ncol=2)
Y1<-Y/60 
sigma2<- matrix(c(var(Y1[,1]),cov(Y1[,1],Y1[,2]),cov(Y1[,1],Y1[,2]),var(Y1[,2])),2,2)
rho<-sigma2[1,2]/sqrt(sigma2[1,1]*sigma2[2,2])
mean(Y1[,1])
mean(Y1[,2])
for (rate3 in 1:20){

rate<-Y1[rate3,]
rate1<-rate/(1-rate)
rate2<-log(rate1)
Sigma11<-(1/(rate[1]*(1-rate[1]))^2)*sigma2[1,1]
Sigma22<-(1/(rate[2]*(1-rate[2]))^2)*sigma2[2,2]
Sigma12<-(1/((rate[1]*(1-rate[1]))*(rate[2]*(1-rate[2]))))*sigma2[1,2]

Sigma2<-matrix(c(Sigma11,Sigma12,Sigma12,Sigma22),2,2)
rate3<-mvrnorm(1000, mu=c(rate2[1],rate2[2]), Sigma2)
x<-exp(rate3[,1])/(1+exp(rate3[,1])) 

# this is not really "stacking" 
# because your code was overwriting x values each time through the loop.
 X[ rate3 , ] <- x   # save to single row at a time

y<-exp(rate3[,2])/(1+exp(rate3[,2]))  # not sure what you wanted to do with these
# print(x)    # and DO NOT PRINT 1000 item vectors to screen!
}


David Winsemius
Alameda, CA, USA