Message-ID: <BAY147-W14D4AB1393994B4D0CCCA5C3DA0@phx.gbl>
Date: 2011-11-04T14:51:41Z
From: Monica Pisica
Subject: How to write a shapefile with projection
Hi,
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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.
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Libraries loaded are: sp, rgdal, raster, maptools
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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
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#Get the projection from a raster ?named llev I have loaded before:
crs <- projection(llev)
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# get a spatial point data frame from my data
crest.sp <- SpatialPointsDataFrame(try[,1:2], try,
proj4string=CRS(crs))
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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?
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#write the shapefile
writePointsShape(crest.sp, "I:/LA_levee/Shape/llev_crest_pts6")
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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.
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Thanks,
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Monica
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