[R] Binomial

[David Winsemius]

On May 12, 2011, at 5:02 AM, Alexander Engelhardt wrote:

> Am 12.05.2011 10:46, schrieb blutack:
>> Hi, I need to create a function which generates a Binomial random  
>> number
>> without using the rbinom function. Do I need to use the choose  
>> function or
>> am I better just using a sample?
>> Thanks.
>
> I think I remember other software who generates binomial data with  
> e.g. pi=0.7 by
>
> pi <- 0.7

I hope Allan knows this and is just being humorous here,  but for the  
less experienced in the audience ... Choosing a different threshold  
variable name might be less error prone. `pi` is one of few built-in  
constants in R and there may be code that depends on that fact.

 > pi
[1] 3.141593
 > pi <- 0.7
 > pi
[1] 0.7
 > rm(pi)
 > pi
[1] 3.141593

> x <- runif(100)>pi
> summary(x)

Another method would be:

  x <- sample(c(0,1) , 100, replace=TRUE,  prob=c(0.7, 0.3) )

-- 

David Winsemius, MD
West Hartford, CT