[R] Question on Reduce + rollmean

[Muhammad Rahiz]

Let me rephrase;

Given x as

> x

[[1]]
   V1 V2 V3
[1,]  1  1  1
[2,]  2  2  2
[3,]  3  3  3

[[2]]
   V1 V2 V3
[1,]  4  4  4
[2,]  5  5  5
[3,]  6  6  6

[[3]]
   V1 V2 V3
[1,]  7  7  7
[2,]  8  8  8
[3,]  9  9  9

I'd like to calculate the moving average (interval = 2) i.e.

( x[[1]] + x[[2]] ) / 2
( x[[2]] + x[[3]] ) / 2
... and so on.

The desired output will return

2.5 2.5 2.5
3.5 3.5 3.5
4.5 4.5 4.5

5.5 5.5 5.5
6.5 6.5 6.5
7.5 7.5 7.5




Muhammad Rahiz  |  Doctoral Student in Regional Climate Modeling
Climate Research Laboratory, School of Geography & the Environment	
Oxford University Centre for the Environment, University of Oxford
South Parks Road, Oxford, OX1 3QY, United Kingdom
Tel: +44 (0)1865-285194	 Mobile: +44 (0)7854-625974
Email: muhammad.rahiz at ouce.ox.ac.uk



milton ruser wrote:
> Dear M.Rahiz,
>
> Unfortunatelly I can't reproduce your example.
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html<http://www.r-project.org/posting-guide.html>
>
> bests
>
> milton
> On Sat, Jan 2, 2010 at 9:26 AM, Muhammad Rahiz <muhammad.rahiz at ouce.ox.ac.uk<mailto:muhammad.rahiz at ouce.ox.ac.uk>> wrote:
> Hello useRs,
>
> I'd like to perform a moving average on the dataset, xx. I've tried combining the functions Reduce and rollmean but it didn't work.
>
>   
>> r <- function(n) rollmean(n, 2) # where 2 = averaging interval
>> output < - Reduce("r", x)
>>     
> Error in f(init, x[[i]]) : unused argument(s) (x[[i]])
>
> Is there anything wrong with the code in the first place?
>
> where
>   
>> x
>>     
>
> [[1]]
>    V1 V2 V3
> [1,]  1  1  1
> [2,]  2  2  2
> [3,]  3  3  3
>
> [[2]]
>    V1 V2 V3
> [1,]  4  4  4
> [2,]  5  5  5
> [3,]  6  6  6
>
> [[3]]
>    V1 V2 V3
> [1,]  7  7  7
> [2,]  8  8  8
> [3,]  9  9  9
>
> The moving average is to be performed on
>
> 1,4,7 = (1+4)/2 , (4+7)/2
> 2,5,8 = ..
> 3,6,9 = ..
>
> Thanks
>
> Muhammad
>
> --
> Muhammad Rahiz  |  Doctoral Student in Regional Climate Modeling
> Climate Research Laboratory, School of Geography & the Environment
> Oxford University Centre for the Environment, University of Oxford
> South Parks Road, Oxford, OX1 3QY, United Kingdom
> Tel: +44 (0)1865-285194  Mobile: +44 (0)7854-625974
> Email: muhammad.rahiz at ouce.ox.ac.uk<mailto:muhammad.rahiz at ouce.ox.ac.uk>
>
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html<http://www.r-project.org/posting-guide.html>
> and provide commented, minimal, self-contained, reproducible code.
>
>
>