Hi there,
I have a SpatialGridDataFrame object and I wish to round the coordinates
associated with the grid to three decimal places in order to match points in
this object with points on another spatial object where the coordinates are
recorded to three decimal places.
Some information about the obj. It is quite a large grid that covers Australia
with over 2 million points in it.
> coords1 <- coordinates(obj)
> dim(coords1)
[1] 2287841 2
> head(coords1)
x y
[1,] 112.0013 -9.999004
[2,] 112.0263 -9.999004
[3,] 112.0513 -9.999004
[4,] 112.0763 -9.999004
[5,] 112.1013 -9.999004
[6,] 112.1263 -9.999004
>
> o...@coords
x y
[1,] 112.0013 -43.999004
[2,] 154.0013 -9.999004
> bbox(obj)
min max
x 111.9888 154.013789
y -44.0115 -9.986504
>
My first attempt to do the rounding was based on the coordinates function. When
I read the help file it indicates that one can set the coordinates by passing
a matrix here. I get an error as listed below.
> ## First suggestion
> coordinates(obj) <- round(coordinates(obj),3)
Error in `coordinates<-`(`*tmp*`, value = c(112.001, 112.026, 112.051, :
setting coordinates cannot be done on Spatial objects, where they have
already been set
A second way was suggested to me that involved rounding o...@coords directly.
This produces no errors but also doesn't do the job as you can see below. It
does round the o...@coords part but this doesn't have any effect on
coordinates(obj) or on bbox(obj).
> ## Second suggestion
> roundcoordinates = function(obj, r = 3) {
+ o...@coords = round(o...@coords, r)
+ obj
+ }
>
> obj <- roundcoordinates(obj)
>
> o...@coords
x y
[1,] 112.001 -43.999
[2,] 154.001 -9.999
> bbox(obj)
min max
x 111.9888 154.013789
y -44.0115 -9.986504
>
> coords2 <- coordinates(obj)
> head(coords2)
x y
[1,] 112.0013 -9.999004
[2,] 112.0263 -9.999004
[3,] 112.0513 -9.999004
[4,] 112.0763 -9.999004
[5,] 112.1013 -9.999004
[6,] 112.1263 -9.999004
>
Does anyone know how to go about this in a way that will also not cause other
potential problems - ie changing o...@coords doesn't automatically update
coordinates(obj) or bbox(obj).
Thanks in advance,
David
Dr David Clifford
Research Scientist
CSIRO Division of Mathematics, Informatics and Statistics
Phone: +61 7 3214 2816 | Fax: +61 7 3214 2855
david.cliff...@csiro.au | www.csiro.au |
www.csiro.au/people/David.Clifford.html
Address: CSIRO Long Pocket Laboratories, 120 Meiers Road, INDOOROOPILLY QLD
4068
New Postal Address from Nov 2010: CSIRO, EcoSciences Precinct, PO Box 2583,
Brisbane, QLD 4001
New Street Address from Nov 2010: CSIRO, EcoSciences Precinct, 41 Boggo Road,
Annerley, QLD 4103
New Phone from Nov 2010: +61 7 3833 5532
PLEASE NOTE
The information contained in this email may be confidential or privileged. Any
unauthorised use or disclosure is prohibited. If you have received this email
in error, please delete it immediately and notify the sender by return email.
Thank you. To the extent permitted by law, CSIRO does not represent, warrant
and/or guarantee that the integrity of this communication has been maintained
or that the communication is free of errors, virus, interception or
interference.
Please consider the environment before printing this email.
_______________________________________________
R-sig-Geo mailing list
R-sig-Geo@stat.math.ethz.ch
https://stat.ethz.ch/mailman/listinfo/r-sig-geo
