decimals in NA value using raster::writeRaster with .ascii format

Thu, Apr 10, 2014 5:06 PM

Zack,

You are using:     dataType="INT2U"

but it should be:     datatype="INT2U"  # (or any other INT data type)

That fixes it. If the datatype is FLT* (the default), the first value
gets decimals to assure that GDAL and others treat the values as
floats, not integers.

Robert

On Thu, Apr 10, 2014 at 3:36 PM, Jonathan Greenberg <jgrn at illinois.edu> wrote:

Zack:

Hopefully Robert will get back to you (I confirmed it -- it looks like
a bug to me) -- but in the meantime, you might want to try my
gdalUtils package, which uses gdal_translate to convert files.  You
can use one of the many ASCII formats -- you'll want to use parameters
like:
gdal_translate(...,a_nodata=-9999,ot="UInt16",format="...")

You can see the available formats at: http://www.gdal.org/formats_list.html

--j



--

On Thu, Apr 10, 2014 at 5:29 PM, Zack Holden <zaholdenfs at gmail.com> wrote:

Thanks for getting back to me Jonathan.

In reality, I am creating the files from an existing DEM. However, I
get the same behavior regardless of whether I generate the file in R
(as with my example code) or with actual data.
I have since tested on 4 machines. One windows machine with an older
version of R successfully generates the desired ascii file without the
decimals. The other 3 computers (Linux and windows machines) add the
decimals. As a workaround, I've tried using -Inf as my NAflag. This
eliminates the decimals, but results in a large string of white space
in front of the first row of data. These still cause problems for
PCraster (the next step in the processing chain).

I'm still stumped.

Thanks again,
Zack


On Thu, Apr 10, 2014 at 4:22 PM, Jonathan Greenberg <jgrn at illinois.edu> wrote:

Zack:

Are you creating the files from within R, or are you just trying to
convert an existing file?  If the latter, can you make one of those
files available (e.g. via google drive or dropbox or something like
that)?

--j

On Thu, Apr 10, 2014 at 3:06 PM, Zack Holden <zaholdenfs at gmail.com> wrote:

Dear list,

I am creating ascii files as inputs to the PCraster software (no other
gdal format is allowed). When I write my ascii file using
raster::writeRaster, the first cell of every raster that I write has a
large number of decimal values appended to it. This causes errors
later in the model workflow.

This also happens to the first NA value in the file, so that all NA
values in the file are e.g. -9999 except the first cell. which appears
as: -9999.00000000000

Can anyone suggest a method for ensuring that all of my NA values are
identical and with no trailing decimals?

A small reproducible example follows. Any help or suggestions is appreciated.

Thanks,
Zack

##################
# start code
require(raster)
r <- raster(nrows=2, ncols=2, xmn=0, xmx=2, ymn=0, ymx=2)
r <- setValues(r, seq(1:ncell(r)))
rexpand <- extend(r, c(2,2))
NAvalue(rexpand) <- -9999

temp.dir <- "/home/zholden/"
writeRaster(rexpand, file=paste(temp.dir, "testraster.asc",sep=""),
NAflag=-9999, dataType="INT2U", overwrite=T)
# end code
##################

# opening in a text editor reveals trailing decimals in the first NA value.
system(paste("gedit ", temp.dir, "testraster.asc", sep=""))

################################
 sessionInfo()
R version 3.0.2 (2013-09-25)
Platform: x86_64-redhat-linux-gnu (64-bit)

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C
LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8
LC_MONETARY=en_US.UTF-8
 [6] LC_MESSAGES=en_US.UTF-8    LC_PAPER=en_US.UTF-8       LC_NAME=C
               LC_ADDRESS=C               LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
[1] rgdal_0.8-16  raster_2.2-12 sp_1.0-14

loaded via a namespace (and not attached):
[1] grid_3.0.2      lattice_0.20-23 tools_3.0.2

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decimals in NA value using raster::writeRaster with .ascii format

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