hxd1011 - 10 months ago 68

R Question

I am calculating the cost for a data set. Is there any way to simplify this nested for loop? Should I use apply or matrix multiplication?

More Background: this is muti-class logistic loss will be used in machine learning. and y_m is a indicator matrix that derived from label y (classification for 10 labels). I am simplify the problem to have a minimal reproducible code by randomly generate h2 and y.

`h2=matrix(runif(5000*10),ncol=10)`

y=round(runif(5000)*9)+1

y_m <- matrix(0,ncol=10,nrow=length(y))

y_m[cbind(1:length(y),y)] <- 1

J=0

for(i in 1:5000){

for(k in 1:10){

J=J-y_m[i,k]*log(h2[i,k])-(1-y_m[i,k])*log(1-h2[i,k]);

}

}

J

Source (Stackoverflow)