[R-sig-Geo] decimals in NA value using raster::writeRaster with .ascii format

Fri Apr 11 02:06:23 CEST 2014

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
>>>>
>>>> _______________________________________________
>>>> R-sig-Geo mailing list
>>>> R-sig-Geo at r-project.org
>>>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>>
>>>
>>>
>>> --
>>> Jonathan A. Greenberg, PhD
>>> Assistant Professor
>>> Global Environmental Analysis and Remote Sensing (GEARS) Laboratory
>>> Department of Geography and Geographic Information Science
>>> University of Illinois at Urbana-Champaign
>>> 259 Computing Applications Building, MC-150
>>> 605 East Springfield Avenue
>>> Champaign, IL  61820-6371
>>> Phone: 217-300-1924
>>> http://www.geog.illinois.edu/~jgrn/
>>> AIM: jgrn307, MSN: jgrn307 at hotmail.com, Gchat: jgrn307, Skype: jgrn3007
>
>
>
> --
> Jonathan A. Greenberg, PhD
> Assistant Professor
> Global Environmental Analysis and Remote Sensing (GEARS) Laboratory
> Department of Geography and Geographic Information Science
> University of Illinois at Urbana-Champaign
> 259 Computing Applications Building, MC-150
> 605 East Springfield Avenue
> Champaign, IL  61820-6371
> Phone: 217-300-1924
> http://www.geog.illinois.edu/~jgrn/
> AIM: jgrn307, MSN: jgrn307 at hotmail.com, Gchat: jgrn307, Skype: jgrn3007
>
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