On 12-08-18 15:12, Roger Bivand wrote:
On Sun, 12 Aug 2018, Paulo van Breugel wrote:
Dear devs,
The function getLocationProj returns an spproj-compliant PROJ.4
string of projection information (using internally /g.proj -jf/).
However, when writing a vector layer to the grass database using the
writeVECT function, it (expects the projection information in the
format returned by /g.proj -g/ (checking the code, this is because it
uses v.in.ogr I guess).
For example, if running R from within a grass session with the NC
location: I have a vector layer "klatifolia" in latlong which I
project it to match the projection of the NC location. Next, I write
it to the grass database using writeVECT:
proj <- getLocationProj()
KLnew <- spTransform(KL, proj)
writeVECT(SDF=KLnew[,c(1,2,5)], vname="KLatifolia", driver="SQLite")
This results in an error telling that the projection of dataset does
not appear to match current location.
Location PROJ_INFO is:
name: Lambert Conformal Conic
proj: lcc
datum: nad83
a: 6378137.0
es: 0.006694380022900787
lat_1: 36.16666666666666
lat_2: 34.33333333333334
lat_0: 33.75
lon_0: -79
x_0: 609601.22
y_0: 0
no_defs: defined
Dataset PROJ_INFO is:
name: unnamed
ellps: grs80
proj: lcc
lat_1: 36.16666666666666
lat_2: 34.33333333333334
lat_0: 33.75
lon_0: -79
x_0: 609601.22
y_0: 0
towgs84: 0,0,0,0,0,0,0
no_defs: defined
ERROR: datum
I can obviously run writeVECT with v.in.ogr_flags="o", but is there a
way that writeVECT can check against the spproj-compliant proj.4
string? Or is this something that should be dealt with at the
v.in.ogr side?
Short answer - after inspecting the two, and checking that they are
the same, use v.in.ogr_flags="o".
Long answer: the PROJ migration from 4.* to 5.* and further is
shifting things everywhere, so handling in GRASS and sf/rgdal will
also change. On the R side, we are waiting for the GDAL barn-raising
project (writing C++ classes for PROJ) to complete before considering
moving to the pipeline model and possible new representations.
Roger
Hi Roger, thanks for the reply, all clear, I'll keep on using
v.in.ogr_flags="o".
Best wishes,
Paulo
sessionInfo()
R version 3.4.4 (2018-03-15)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 18.04.1 LTS
Matrix products: default
BLAS: /usr/lib/x86_64-linux-gnu/blas/libblas.so.3.7.1
LAPACK: /usr/lib/x86_64-linux-gnu/lapack/liblapack.so.3.7.1
locale:
[1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C LC_TIME=en_US.UTF-8
[4] LC_COLLATE=en_US.UTF-8 LC_MONETARY=en_US.UTF-8
LC_MESSAGES=en_US.UTF-8
[7] LC_PAPER=en_US.UTF-8 LC_NAME=C LC_ADDRESS=C
[10] LC_TELEPHONE=C LC_MEASUREMENT=en_US.UTF-8
LC_IDENTIFICATION=C
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] ggplot2_3.0.0 mapr_0.4.0 raster_2.6-7 rgrass7_0.1-11
XML_3.98-1.12 maptools_0.9-3
[7] sp_1.3-1 rgbif_1.0.2
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