[R] Question on Reduce + rollmean
Muhammad Rahiz
muhammad.rahiz at ouce.ox.ac.uk
Thu Jan 7 19:25:18 CET 2010
Yes, should be
1. out[[i]], instead of t[[i]].
2. x1[c(i:(i+1))] # For this case, I was trying out the rolling sum.
Muhammad Rahiz | Doctoral Student in Regional Climate Modeling
Climate Research Laboratory, School of Geography & the Environment
Oxford University Centre for the Environment
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
Gabor Grothendieck wrote:
> That gives an error when I run it. I think you want this:
>
> m <- matrix(1:3,3,3)
> x1 <- list(m, m+1, m+2, m+3, m+4)
>
> out <- list()
> for(i in 1:4) out[[i]] <- (x1[[i]] + x1[[i+1]]) / 2
>
>
> On Thu, Jan 7, 2010 at 12:28 PM, Muhammad Rahiz
> <muhammad.rahiz at ouce.ox.ac.uk> wrote:
>
>> Dear Gabor & Henrique,
>>
>> Thanks for your suggestions on the above problem. The following is more
>> traditional and unfanciful but it works. Suitable for a prodige like
>> myself...
>>
>> m <- matrix(1:3,3,3)
>> x1 <- list(m, m+1, m+2, m+3, m+4)
>> out <- list()
>> for (i in 1:4){
>> t[[i]] <- Reduce("+", x1[c(i:i+1)])
>> }
>>
>> Muhammad
>>
>> Muhammad Rahiz | Doctoral Student in Regional Climate Modeling
>>
>> Climate Research Laboratory, School of Geography & the Environment
>> Oxford University Centre for the Environment
>> 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
>>
>>
>>
>>
>>
>>
>> Gabor Grothendieck wrote:
>>
>>> Here is a variation which also uses head and tail:
>>>
>>> mapply(function(x, y) (x + y)/2, tail(x, -1), head(x, -1), SIMPLIFY =
>>> FALSE)
>>>
>>>
>>> On Mon, Jan 4, 2010 at 12:37 PM, Henrique Dallazuanna <wwwhsd at gmail.com>
>>> wrote:
>>>
>>>
>>>> For this example try this:
>>>>
>>>> lapply(lapply(list('head', 'tail'), do.call, list(x, n = -1)),
>>>> function(x)Reduce('+', x)/2)
>>>>
>>>>
>>>> On Mon, Jan 4, 2010 at 1:54 PM, Muhammad Rahiz
>>>> <muhammad.rahiz at ouce.ox.ac.uk> wrote:
>>>>
>>>>
>>>>> Thanks Gabor,
>>>>>
>>>>> It works alright. But is there alternative ways to perform rollmean
>>>>> apart
>>>>> from permutating the data?
>>>>> Possibly combining the Reduce and rollmean functions?
>>>>>
>>>>> The easiest but traditional way is
>>>>>
>>>>>
>>>>>
>>>>>> (x[[1]]+x[[2]]) / 2
>>>>>> (x[[2]]+x[[3]]) / 2
>>>>>>
>>>>>>
>>>>> Muhammad Rahiz | Doctoral Student in Regional Climate Modeling
>>>>>
>>>>> Climate Research Laboratory, School of Geography & the Environment
>>>>> Oxford University Centre for the Environment
>>>>> 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
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Gabor Grothendieck wrote:
>>>>>
>>>>>
>>>>>> Try apply:
>>>>>>
>>>>>> library(zoo) # rollmean
>>>>>>
>>>>>> # test data
>>>>>> m <- matrix(1:3, 3, 3)
>>>>>> x <- list(m, m+3, m+6)
>>>>>>
>>>>>> # convert to array
>>>>>> a <- array(unlist(x), c(3, 3, 3)); a
>>>>>>
>>>>>> # apply rollmean and permute to desired form
>>>>>> aa <- apply(a, 1:2, rollmean, k = 2)
>>>>>> aperm(aa, c(2, 3, 1))
>>>>>>
>>>>>> The last line outputs:
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>> aperm(aa, c(2, 3, 1))
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>> , , 1
>>>>>>
>>>>>> [,1] [,2] [,3]
>>>>>> [1,] 2.5 2.5 2.5
>>>>>> [2,] 3.5 3.5 3.5
>>>>>> [3,] 4.5 4.5 4.5
>>>>>>
>>>>>> , , 2
>>>>>>
>>>>>> [,1] [,2] [,3]
>>>>>> [1,] 5.5 5.5 5.5
>>>>>> [2,] 6.5 6.5 6.5
>>>>>> [3,] 7.5 7.5 7.5
>>>>>>
>>>>>>
>>>>>> On Sat, Jan 2, 2010 at 10:00 AM, Muhammad Rahiz
>>>>>> <muhammad.rahiz at ouce.ox.ac.uk> wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>> 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>
>>>>>>>>
>>>>>>>> ______________________________________________
>>>>>>>> R-help at r-project.org<mailto:R-help at r-project.org> mailing list
>>>>>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>>>>>> 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.
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>> ______________________________________________
>>>>>>> R-help at r-project.org mailing list
>>>>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>>>>> PLEASE do read the posting guide
>>>>>>> http://www.R-project.org/posting-guide.html
>>>>>>> and provide commented, minimal, self-contained, reproducible code.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>> ______________________________________________
>>>>> R-help at r-project.org mailing list
>>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>>> PLEASE do read the posting guide
>>>>> http://www.R-project.org/posting-guide.html
>>>>> and provide commented, minimal, self-contained, reproducible code.
>>>>>
>>>>>
>>>>>
>>>> --
>>>> Henrique Dallazuanna
>>>> Curitiba-Paraná-Brasil
>>>> 25° 25' 40" S 49° 16' 22" O
>>>>
>>>> ______________________________________________
>>>> R-help at r-project.org mailing list
>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>> PLEASE do read the posting guide
>>>> http://www.R-project.org/posting-guide.html
>>>> and provide commented, minimal, self-contained, reproducible code.
>>>>
>>>>
>>>>
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