Hello,
Have a look at spTransform (in rgdal package) and the EPSG code of the
desired projection (this is to me the easiest way not to mess with
digits and various copy errors that can be made while writing the
projection properties) at www.spatialreference.org
then, you just have to do something like this
library(rgdal)
data<-read.table ("mydata.txt", h=T, sep=",") #your original dataset
coordinates(data)<-~ X + Y # where X and Y stand for the name of your
lat/lon columns
proj4string(data)<-CRS("+init=epsg:4326") #if your coordinates are in WGS84
data.proj<-spTransfrom(data,
CRS("+init=epsg:the.correct.epsg.number.of.your.projection")
HTH
Alex
Le 24/08/2010 16:51, Jonathan Marc Bearak a écrit :
Hi,
I'm new to GIS and have been trying to convert latitude and longitude to/from
state plane coordinates.
I've tried using the project() program from the proj4 library to convert
lat/lng to FIPS 3104 (New York State Long Island).
No matter how I go about this, however, the coordinates come out wrong. E.g.,
"+proj=lcc +lat_1=40.66666666666666 +lat_2=41.03333333333333
+lat_0=40.16666666666666 +lon_0=-74 +x_0=300000 +y_0=0 +units=ft +no_defs
+datum=NAD83",
"+proj=lcc +a=6378137 +es=.0066943800229 +lon_0=-74
+lat_1=41d2 +lat_2=40d40 +lat_0=40d10 +x_0=300000 +y_0=0 +units=ft +no_defs
+datum=NAD83",
E.g., if I try the inverse, to convert 1062791, 209606.6 to lat/lng, project()
prints: 43.04762 -76.89626. The correct coordinates, however, are: 40.7416495
-073.7165681.
I've been reading the mailing lists and searching Google and R project PDFs and
manual pages without any luck for an embarrassingly long number of hours
without any luck.
Thanks for any help.
Best,
Jonathan
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