[R] How to write a shapefile with projection

[Monica Pisica]

Hi,

 

I am trying to write a shapefile with projection. I have
my data in a data.frame called try and consists in xy coordinates and a
numerical attribute value z1.

 

Libraries loaded are: sp, rgdal, raster, maptools

 

head(try)

         x           y                    z1

1 610237.1          3375751
             8.221

2 610236.1          3375750
             8.153

3 610236.1          3375749
             8.275

4 610236.1          3375748
             8.251

5 610236.1          3375747
             8.217

6 610236.1          3375746
             8.196

 

#Get the projection from a raster  named llev I have loaded before:

crs <- projection(llev)

 

# get a spatial point data frame from my data

crest.sp <- SpatialPointsDataFrame(try[,1:2], try,
proj4string=CRS(crs))

 

summary(crest.sp)

Object of class SpatialPointsDataFrame

Coordinates:

        min               max

x  610235.1         610354.1

y 3374862.4        3375751.4

Is projected: TRUE 

proj4string :

[+proj=utm +zone=15 +ellps=GRS80 +datum=NAD83 +units=m
+no_defs +towgs84=0,0,0]

Number of points: 890

Data attributes:

                x          y                 z1       

 Min.   :  610235   Min. : 3374862   Min.: 6.966  

 1st
Qu.:610269   1st Qu.:3375085   1st Qu.:7.570  

 Median
:610298   Median :3375307   Median :7.901  

 Mean   :610300  
Mean   :3375307  
Mean   :7.882  

 3rd
Qu.:610334   3rd Qu.:3375529   3rd Qu.:8.180  

 Max.   :610354  
Max.   :3375751   Max.  
:8.756  

 

#write the shapefile

writePointsShape(crest.sp, "I:/LA_levee/Shape/llev_crest_pts6")

 

If I load this shapefile in ArcGIS is has no projection.
I also looked at the write.shapefile command from shapefiles library and again I
get a file without projection. Is there any way to write the projection for the
shapefile in R? Probably I can do something in ArcGIS, but I would like to have
my shapefile from R complete.

 

Thanks,

 

Monica