[R-sig-Geo] Using raster to import headerless ASCIIs?

[Robert J. Hijmans]

Jonathan,
A little shorter:

library(raster)

s <- read.fwf("soilwhc.dat", widths=rep(5,36))
r <- raster(ncol=720, nrow=360, xmn=0, xmx=360)
values(r) <- as.vector(t(as.matrix(s)))
r <- rotate(flip(r, 'y'))

plot(r)

Robert

On Sat, May 11, 2013 at 10:45 AM, Jonathan Greenberg <jgrn at illinois.edu> wrote:
> I was trying to solve this entirely within R -- this was my solution:
>
> # The file is fixed width format, each number has a width of 5,
> # with 36 numbers to a line:
> soilwhc_dunne_raw_df <- read.fwf("soilwhc.dat",widths=rep(5,36))
> soilwhc_dunne_raw_vector <- c(t(data.matrix(soilwhc_dunne_raw_df)))
> soilwhc_dunne_raw_matrix <-
> matrix(soilwhc_dunne_raw_vector,ncol=360,nrow=720)
> # The image comes out flipped along the y axis:
> soilwhc_dunne_raw <- flip(raster(t(soilwhc_dunne_raw_matrix)),"y")
> extent(soilwhc_dunne_raw) <- extent(0,360,-90,90)
> projection(soilwhc_dunne_raw) <- CRS("+proj=longlat +datum=WGS84")
> # We'll also rotate it:
> soilwhc_dunne_raw_rotate <- rotate(soilwhc_dunne_raw)
>
> I was curious if there was a more elegant solution to this?  Either way,
> thanks for the response!
>
> --j
>
>
> On Fri, May 10, 2013 at 3:03 PM, Etienne B. Racine <etiennebr at gmail.com>wrote:
>
>>   Jonathan,
>>
>>  You should set an header in the first file. Dunne_soil.dat is recognized
>> as an Ascii Grid by GDAL because it has an header :
>> ncols         720
>> nrows         360
>> xllcorner     -180
>> yllcorner     -90
>> cellsize      0.5
>> NODATA_value  -9999
>>
>>  soilwhc.dat has no header. Also NA is coded with no space (-99.0-99.0).
>> Maybe if you search and replace -99.0 by -9999[space] this would make it
>> more standard. The lines are also rather short (36), but very long (7200).
>> I guess each row is indeed 10 lines. It would share the same header than
>> dunne_soil.dat. So you have some reformatting to get it working.
>>
>>  Etienne
>>
>>
>> 2013/5/10 Jonathan Greenberg <jgrn at illinois.edu>
>>
>>> r-sig-geo'ers:
>>>
>>> I'm trying some random hacks, but was wondering if there is a more
>>> efficient way to import the following file:
>>> ftp://ftp.daac.ornl.gov/data/global_soil/Dunne/data/soilwhc.dat
>>>
>>> as a raster().  The file is a fixed width file (width=5) of floating point
>>> values, but had the Arc header stripped off.  A reference file that DOES
>>> work with raster is:
>>>
>>> ftp://ftp.daac.ornl.gov/data/global_soil/Dunne/data/dunne_soil.dat
>>> reference_raster <- raster(dunne_soil.dat)
>>> # This has the same number of rows and columns and resolution as
>>> # the file above.
>>>
>>> Thoughts on the most efficient way to convert the first file to a workable
>>> raster?
>>>
>>> --j
>>>
>>> --
>>> 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
>>> 607 South Mathews Avenue, MC 150
>>> Urbana, IL 61801
>>> 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
> 607 South Mathews Avenue, MC 150
> Urbana, IL 61801
> 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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