CODEWITHSUNDEEP
rloopsdistributionpoisson
Rojer
Rojer

Reputation: 335

How to handle a Poisson distribution in R

Consider the Poisson distribution x1, x2, ... ~ pois(1) with lambda=1. I want to write a function that receives a number as input (consider it a) and gives us as output the smallest n (minimum n) which is true for sum(xi)>=a, i=1:n. I think using a while loop could be fine for this situation (but I am not sure that it's the best way). Perhaps it can be done using other loops like for loop. I do not know how to handle this situation containing a Poisson distribution in R?

Upvotes: 0

Views: 506

Answers (1)

Rui Barradas
Rui Barradas

Reputation: 76402

A while loop is simple enough to code. It accumulates the values of rpois in s for sum while s < a, counting the iterations in n.

minpois <- function(a){
  n <- 0L
  s <- 0L
  while(s < a) {
    n <- n + 1L
    s <- s + rpois(1L, lambda = 1)
  }
  n
}

set.seed(2020)
minpois(10)
#[1] 12

Upvotes: 2

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