On Mon, 19 Jul 2010, tim.haer...@lwf.bayern.de wrote:
Hello !
I want to import a raster into R using the readGDAL() function.
Unfortunately the coordinates of my raster have decimal places. After
importing the file the decimal places get lost. It seems the GDAL rounds
the coordinates. Is it possible to read the decimal places?
Try setting a different value for options("digits") to be used by the
print() method you are calling invisibly. Showing a floating point number
must involve arbitrary rounding, and if you haven't specified a different
number of digits, you get the default:
x <- 4344198.9375000019
print(x)
print(x, digits=16)
print(x, digits=20)
Notice that your example number cannot be represented in double precision,
as after 4344198.93750001 there is no precision left, and any operations
(such as multiplication) will erode it anyway. In any case, you are
probably dealing with a missing part of the size of 0.0000019 mm, which
might just be more precise than the measurements were.
Hope this clarifies,
Roger
Here a little example:
The header of my ASCII file:
NCOLS 202
NROWS 201
XLLCENTER 4344198.9375000019
YLLCENTER 5537700.3750000028
CELLSIZE 20.000000
NODATA_VALUE -99999
myraster <- readGDAL("raster.asc")
myras...@coords
x y
[1,] 4344199 5537700
[2,] 4348219 5541700
Thank you.
TIM
-----------------
Tim Häring
Bavarian State Institute of Forestry
Department of Forest Ecology
Hans-Carl-von-Carlowitz-Platz 1
D-85354 Freising
E-Mail: tim.haer...@lwf.bayern.de
http://www.lwf.bayern.de
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--
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: roger.biv...@nhh.no
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