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rmatrixprobability-distribution

How to create a matrix with probability distribution in R


I want to create a matrix in R with element [-1,0,1] with probability [1/6, 2/3, 1/6] respectively. The probability may change during runtime. for static probability I have got the output but the problem is dynamic change in the probability. for example, If I create a matrix for the above probability with [sqrt(3),0,-sqrt(3)], the required output is.

Note: The Probability should not be static as mentioned. It may vary during runtime.

Kindly help to solve this.

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Solution

  • Supposing you want a 2x3 matrix:

    matrix(sample(c(-1,0,1), size=6, replace=TRUE, prob=c(1/6,2/3,1/6)), nrow=2)
    

    So you sample from the values you want, with probabilities defined in prob. This is just a vector, but you can make it into a matrix of the desired shape using matrix afterwards. Replace the probabilities by a variable instead of values to not make it static.

    If the numbers should be distributed according to a certain scheme rather than randomly drawn according to a probability, replicate the vector elements and shuffle them:

     matrix(sample(rep(c(-1,0,1), times=c(1,4,1))), nrow=2)