# [R] estimate value from simulations

David Winsemius dwinsemius at comcast.net
Thu May 16 18:40:13 CEST 2013

```On May 15, 2013, at 11:24 PM, Pascal Oettli wrote:

> Hi,
>
> You probably should read R documentation and learn how to use "seq"
>
> ?seq
> ?rowMeans
>
> HTH,
> Pascal
>
>
> On 05/16/2013 03:17 PM, Zilefac Elvis wrote:
>> Hello,
>>
>> I need your help on this matrix:
>>
>>
>>  1 1 1 1 1 1
>>  2 2 2 2 2 2
>>  3 3 3 3 3 3
>>  5 5 5 5 5 5
>>  2 2 2 2 2 2
>>  3 3 3 3 3 3
>>  6 6 6 6 6 6
>>  2 2 2 2 2 2
>>  3 3 3 3 3 3
>>  1 1 1 1 1 1
>>  2 2 2 2 2 2
>>  3 3 3 3 3 3
>>
>> First three rows represent first simulation, next three rows = second simulation etc.
>> I would like to estimate the values in row 1 for example by taking  the mean  of rows 1, 4, 7, 10. Do same for all other rows. So the resulting matrix is
>> 3-by-6.

It seems from the dimensions expected that what your really want is not means of rows but rather means of columns.

matrix( c( colMeans( sim[c(TRUE,FALSE,FALSE), ]), # recycling picks out 1,4,7,10, ...
colMeans( sim[c(FALSE,TRUE,FALSE), ]),
colMeans( sim[c(FALSE,FALSE,TRUE), ])), ncol=6, byrow=TRUE)

--
David Winsemius
Alameda, CA, USA

```