[R-sig-Geo] Error in basename(x) : path too long

[Ben Tupper]

Hi again,

A late thought - I'm still on the first cups of coffee.

It looks to me like you are iterating over a stack to select certain layers to sum.  You could achieve the same outcome with possibly much less work.  The following example will create a sum of 24-layer blocks along a stack of rasters. 

# from https://gist.github.com/btupper/20879e0b46e5ed63d402d7cff424dbb7
#' Split a vector into groups of MAX (or possibly fewer)
#'
#' @param v vector or list to split
#' @param MAX numeric the maximum size per group
#' @return a list of the vector split into groups
split_vector <- function(v, MAX = 200){
    nv <- length(v)
    if (nv <= MAX) return(list('1' = v))
    split(v, findInterval(1:nv, seq(from = 1, to = nv, by = MAX)))
}


library(raster)

N <- 345
n <- 24
nc <- 4
nr <- 3

R <- raster(matrix(runif(nc*nr), ncol = nc, nrow = nr))

RR <- stack(lapply(seq_len(N), function(i) R))

ix <- split_vector(seq_len(N), MAX = n)

SS <- lapply(ix, function(index) sum(RR[[index]]))

So, S[[1]], which looks like this...

$`1`
class       : RasterLayer 
dimensions  : 3, 4, 12  (nrow, ncol, ncell)
resolution  : 0.25, 0.3333333  (x, y)
extent      : 0, 1, 0, 1  (xmin, xmax, ymin, ymax)
coord. ref. : NA 
data source : in memory
names       : layer 
values      : 0.9451534, 20.0503  (min, max)

... is the sum of the first 24 layers of RR. SS[[2]] will be the sum of the next 24, and so on.

Is that what you are trying to do?

Cheers,
Ben




> On Jul 29, 2017, at 7:56 AM, John Wasige <johnwasige at gmail.com> wrote:
> 
> ​Dear all,
> 
> I am running the script below & I get the following error:
> Error in basename(x) : path too long
> ​
> What could be the problem?
> Thanks for your help
> John
> 
> ​### Script​
> 
> setwd("I:/Mauritius2001_2015")  # directory of data
> newlist= read.csv('I:/Mauritius2001_2015/Mauritius.csv',header=F)
> 
> refr <- raster(paste("I:/Mauritius2001_2015/",newlist[i,1],sep = ""))
> refr[!is.na(refr)] <- 0
> for(i in seq(1,345,by=23)){
>  rsum <- refr
>  for(p in 0:22){
>    r <- raster(paste("I:/Mauritius2001_2015/",newlist[i+p],sep = ""))
>    rsum <- rsum + r
>  }
>  #   rsum <- rsum
>  writeRaster(rsum,
> filename=paste("D:/Mauritius2001_2015/Annual/",substr(newlist[i],1,6),".tif",sep=''),
> format="GTiff", overwrite=TRUE)
> }
> 
> 	[[alternative HTML version deleted]]
> 
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Ben Tupper
Bigelow Laboratory for Ocean Sciences
60 Bigelow Drive, P.O. Box 380
East Boothbay, Maine 04544
http://www.bigelow.org

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