[R] Simulation

Wacek Kusnierczyk Waclaw.Marcin.Kusnierczyk at idi.ntnu.no
Thu May 14 16:05:04 CEST 2009


Stefan Grosse wrote:
> Debbie Zhang schrieb:
>   
>> Now, I am trying to obtain the sample variance (S^2) of the 1000 samples that I have generated before.
>>
>> I am wondering what command I should use in order to get the sample variance for all the 1000 samples.
>>
>>  
>>
>> What I am capable of doing now is just typing in
>>
>> var(z[[1]])
>>
>> var(z[[2]])..................... 
>>
>>     

if you have the data produced the for loop way, i.e., as a list of
vectors, you can go the intuitive way:

    vars = list()
    for (i in 1:1000)
       vars[[i]] = z[[i]]

or the unintuitive way:

    vars = lapply(z, var)

if you have the data produced the matrix or replicate way (i.e., a
matrix with columns representing samples), you can go the intuitive way:

    vars = c()
    for (i in 1:1000)
       vars[i] = var(z[,i])

or the unintuitive way:

    vars = apply(z, 2, var)


consider reading an intro to r
    unless you like to receive responses as the one below.

vQ  

> Common please use the package brain 2.0.




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