R help - Feb 2013 - How to calculate the moving average for binary files?

I have 12 binary (raster) files   
https://echange-fichiers.inra.fr/get?k=k3M2jatJyHy65Cs99G4 .
I would like to calculate the moving average for the 12 values for each
pixel in the 12 files.

For a simple vector we can get a moving average by using this :
              
             x <- c(1,2,3,NA,NA,4,6,5,6,4,2,5)
            movingmean <- rollapply(x, 3, FUN = mean, na.rm = T,fill=NA)
now I want to do the same but with binary files and I tried:

    files   <- list.files("C:final-2010", "*.envi",
full.names = TRUE)
    results <- list()
    for (.files in files) {
        # read in the 12 files as a vector of numbers 
        # that we take the average of
        x <- do.call(rbind,(lapply(.files, readBin  , double() , 
                         size = 4 ,n =1440 * 720 , signed = T)))
        # take the moving average across the 12 values 
        # from the 12 files for each pixel
        results[[length(results) + 1L]] <- rollapply(x, 3, FUN = mean,na.rm
= T)
    }
 
But got this error:
 
        Error in seq.default(start.at, NROW(data), by = by) : 
                                 wrong sign in 'by' argument



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On Feb 18, 2013, at 12:28 PM, Jonsson wrote:
> I have 12 binary (raster) files   
> https://echange-fichiers.inra.fr/get?k=k3M2jatJyHy65Cs99G4 .
> I would like to calculate the moving average for the 12 values for each
> pixel in the 12 files.
> 
> For a simple vector we can get a moving average by using this :
> 
>             x <- c(1,2,3,NA,NA,4,6,5,6,4,2,5)
>            movingmean <- rollapply(x, 3, FUN = mean, na.rm = T,fill=NA)
> now I want to do the same but with binary files and I tried:
> 
>    files   <- list.files("C:final-2010", "*.envi",
full.names = TRUE)
>    results <- list()
>    for (.files in files) {
>        # read in the 12 files as a vector of numbers 
>        # that we take the average of
>        x <- do.call(rbind,(lapply(.files, readBin  , double() , 
>                         size = 4 ,n =1440 * 720 , signed = T)))
>        # take the moving average across the 12 values 
>        # from the 12 files for each pixel
>        results[[length(results) + 1L]] <- rollapply(x, 3, FUN =
mean,na.rm
> = T)
>    }
> 
> But got this error:
> 
>        Error in seq.default(start.at, NROW(data), by = by) : 
>                                 wrong sign in 'by' argument
Cross-posting on StackOverflow and Rhelp is deprecated in the Posting Guide.

http://stackoverflow.com/questions/14944824/how-to-calculate-the-moving-averag-for-several-binary-files-in-r

-- 

David Winsemius
Alameda, CA, USA