[R] Random number datasets help

[Marc Schwartz]

Alexandre did say 28 datasets, not 784 (28 * 28)....

Thus, either:

   mapply(rnorm, n = 500, mean = a1, sd = a2)

or

   apply(cbind(a1, a2), 1, function(x) rnorm(500, x[1], x[2]))


HTH,

Marc Schwartz

On Jun 18, 2009, at 12:51 PM, Henrique Dallazuanna wrote:

> Try this also:
>
> a <- expand.grid(a1, a2)
> x <- mapply(rnorm, n = 500, mean = a[,1], sd = a[,2])
>
> On Thu, Jun 18, 2009 at 2:10 PM, Alexandre Lockhart <
> alexandre_georges at hotmail.com> wrote:
>
>>
>> Hello:
>>
>> My problem is that I have a data frame of means, and a data frame of
>> standard deviations which match up to each mean.  I have been  
>> trying to
>> create 500 random numbers in a given dataset for each mean/sd  
>> combination,
>> but I am only able to generate the last value in each data set to  
>> create one
>> dataset (there should be 28 in all).  Examining my code, what can I  
>> change
>> to generate 28 datasets based on respective mean and sds?
>>
>>
>> a1<- 
>> c 
>> (178.07,178.28,178.08,177.74,177.04,178.17,177.58,57.71,59.6,60.92,59.48,59.32,61.59,59.94,28.9,29.82,30.73,25.68,27.93,28.98,29.76,123.48,127.27,127.8,127.2,127.13,126.71,125.5 
>> )
>>
>> a2<- 
>> c 
>> (1.69,1.3,1 
>> ,. 
>> 18,1.53,1.31,1.35,1.83,1.56,1.12 
>> ,. 
>> 74,1.48,1.67,1.53 
>> ,.95,.87,0.03,1.12,1.95,1.22,1.04,1.64,1.83,1,1,1.08,1.35,2.37)
>> for(i in 1:length(a1))
>>   for(j in 1:length(a2))
>>       x<-rnorm(500,mean=a1[i],sd=a2[j])
>>
>> Thank you,
>>
>> Agl