Question

So, I have a script which I would like to create a matrix or data.frame on the fly.

However, I do not know the dimensions of the matrix/frame going in. When I try to just create a blank matrix and adding values, I get the “subscript out of bounds” error,

Here is some of my code:

data <- read.csv("C:/3PP/data.txt", header=F)

parsed = matrix()
for (i in 1:nrow(data))
{
  parsed[data[i,1],data[i,2]+1] = data[i,3]
}

How can I set this up such that this matrix can be generated on the fly, without having to specify the size in the beginning?

Thank you!

Answer 1

Given your problem, you know already the number of rows and columns. You can specify your matrix like:

parsed <- matrix(nrow=max(Data[,1]),
                 ncol=max(Data[,2])+1)

The only other way to grow a matrix is by using rbind() or cbind(), but that can get pretty slow with big matrices.