How to fill matrix with random numbers in R?

Question

expand.grid(i=rexp(5,rate=0.1))

It creates just one col but is there some way to multiply this easily to 5 cols? I mean the matlab-way-of-doing-things

Answer 1

Here's a simple solution:

replicate(rexp(10),20)

Answer 2

you can do something like:

matrix(rexp(200), 10)

And of course use what ever distribution you want.

Answer 3

?matrix will tell you lots! and rexp is the function to generate a random exponential distribution.

mat <- matrix(data = rexp(200, rate = 10), nrow = 10, ncol = 20)

Answer 4

Use the matrix function:

matrix(rexp(200, rate=.1), ncol=20)

ETA: If you want to do it without repeating the 200, you can define a function to do so:

fill.matrix = function(expr, nrow=1, ncol=1) {
    matrix(eval(expr, envir=list(x=nrow*ncol)), nrow=nrow, ncol=ncol)
}

fill.matrix(rexp(x, rate=.1), nrow=10, ncol=20)

The x thus becomes the dummy variable you're talking about. Is that what you're looking for?

Answer 5

You can generate a uniformly distributed 10 by 15 random matrix in the following code line:

matrix(runif(10*15), nrow = 10, ncol = 15)

Answer 6

Use this:

matris=matrix(rnorm(10),5,20)