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

Jonathan Greenberg jgrn at illinois.edu
Fri Apr 11 16:48:57 CEST 2014 

Robert:

What is the practical difference between those two? -- does dataType
get passed off to GDAL, while datatype is interpreted by your R code?

--j

On Thu, Apr 10, 2014 at 7:06 PM, Robert J. Hijmans <r.hijmans at gmail.com> wrote:
> 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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>
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-- 
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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