[R] Re ading and Creating Shape Files
Hello R Community, I have imported a dataset which contain X Y coordinates and would like to recreate a shape file after some data analysis. What i have done is to import some taxlot data and join them based on some criteria. I want to check to see how well the joining went by reviewing the results in GIS. A couple things. I cant seem to import a shape file correctly using the maptools package and the readShapeSpatial. I have tried Building=file(data/input/BuildingShape/Building.shp) Bldg-readShapeSpatial(fn=data/input/BuildingShape/Building,proj4string=NAD83) #-- Bldg-readShapeSpatial(data/input/BuildingShape/Building,proj4string=NAD83) #--- Building=file(data/input/BuildingShape/Building.shp) Bldg-readShapeSpatial(Building,proj4string=NAD83) I know i am mis interpreting the documentation but it doesnt seem like it is very complicated so i am of course confused. Also, i am wondering if i can create a shape file by simply using XY coordinates from a data frame. So for: Ycoord=c( 865296.4, 865151.5, 865457.0 ,865363.4 ,865311.0, 865260.9 ,865210.7 ,865173.3, 865123.6 ,865038.2 ,864841.1 ,864745.4 ,864429.1 ,864795.6 ,864334.9 ,864882.0) Xcoord=c( 4227640 ,4227816 ,4228929 ,4228508 ,4229569 ,4229498 ,4226747, 4226781, 4229597, 4229204, 4228910, 4228959 ,4229465 ,4229794 ,4229596 ,4229082) Lot-c(1900 , 2000, 2100 , 100 ,200 , 300, 400 , 500 , 600 , 701 , 900 , 1000 , 1100, 300 ,100, 200) XYcoord-spCbind(Ycoord,Xcoord) #doesnt work so XYcoord=c(Ycoord,Xcoord) TaxLots-cbind(Ycoord,Xcoord,Lot) writeSpatialShape(XYcoord, TaxLots.., file=data/input/test/Taxlots,strictFilename=FALSE) So help reading in shape files and then creating them using XY coordinates if possible Any help would be appreciated. Thank you. -- View this message in context: http://www.nabble.com/Reading-and-Creating-Shape-Files-tp26098828p26098828.html Sent from the R help mailing list archive at Nabble.com. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Re ading and Creating Shape Files
PDXRugger wrote:
Hello R Community,
I have imported a dataset which contain X Y coordinates and would like
to recreate a shape file after some data analysis. What i have done is to
import some taxlot data and join them based on some criteria. I want to
check to see how well the joining went by reviewing the results in GIS.
A couple things. I cant seem to import a shape file correctly using the
maptools package and the readShapeSpatial. I have tried
Building=file(data/input/BuildingShape/Building.shp)
Bldg-readShapeSpatial(fn=data/input/BuildingShape/Building,proj4string=NAD83)
#--
Bldg-readShapeSpatial(data/input/BuildingShape/Building,proj4string=NAD83)
#---
Building=file(data/input/BuildingShape/Building.shp)
Bldg-readShapeSpatial(Building,proj4string=NAD83)
I know i am mis interpreting the documentation but it doesnt seem like it
is very complicated so i am of course confused.
I haven't used the maptools package for this kind of operation, so I offer
any specific advice. However, the value of proj4string seems to be a little
odd-- unless NAD83 is a variable that contains a string. It should probably
be a quoted list of PROJ4 declarations such as:
proj4string = '+proj=longlat +datum=NAD83'
If maptools is leveraging the sp package, then you probably need to enclose
the string in the CRS() function:
proj4string = CRS('+proj=longlat +datum=NAD83')
Note that the above example assumes coordinates are in lat/lon using the
NAD83 datum. If your data is in a different projection, such as UTM, you
will need to change the PROJ4 string accordingly.
PDXRugger wrote:
Also, i am wondering if i can create a shape file by simply using XY
coordinates from a data frame.
So for:
Ycoord=c( 865296.4, 865151.5, 865457.0 ,865363.4 ,865311.0, 865260.9
,865210.7 ,865173.3,
865123.6 ,865038.2 ,864841.1 ,864745.4 ,864429.1 ,864795.6 ,864334.9
,864882.0)
Xcoord=c( 4227640 ,4227816 ,4228929 ,4228508 ,4229569 ,4229498 ,4226747,
4226781, 4229597,
4229204, 4228910, 4228959 ,4229465 ,4229794 ,4229596 ,4229082)
Lot-c(1900 , 2000, 2100 , 100 ,200 , 300, 400 , 500 , 600 , 701
, 900 , 1000 , 1100,
300 ,100, 200)
XYcoord-spCbind(Ycoord,Xcoord) #doesnt work so
XYcoord=c(Ycoord,Xcoord)
TaxLots-cbind(Ycoord,Xcoord,Lot)
writeSpatialShape(XYcoord, TaxLots..,
file=data/input/test/Taxlots,strictFilename=FALSE)
So help reading in shape files and then creating them using XY coordinates
if possible
Any help would be appreciated. Thank you.
Maybe maptools provides a nice way to do this-- again I haven't used it
much. My shapefile workflow usually centers on the sp and rgdal packages.
First, sp is used to create a spatial object that holds the coordinates and
data. Assuming you have point data:
require(rgdal)
lots - SpatialPointsDataFrame( coords = cbind(Xcoord,Ycoord), data =
data.frame( Lot = Lot ))
*Note that SpatialPointsDataFrame also takes a proj4string argument of the
form:
proj4string = CRS( 'proj declarations' )
I have omitted it since I don't know what projection your data is in.
You can then create a shapefile using the writeOGR() routine in rgdal:
writeOGR( lots, dsn = 'tstShapefile', layer = 'tstShapefile', driver='ESRI
Shapefile')
The readOGR() function can also be used to read a shapefile-- note that you
give it the name of the directory containing the shapefile components and
not the name of an individual component such as 'shapefile.shp'.
Hope this helps!
-Charlie
-
Charlie Sharpsteen
Undergraduate
Environmental Resources Engineering
Humboldt State University
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Re: [R] Re ading and Creating Shape Files
Have you tried readShapePoints writePointsShape both in maptools. Also, I don't think you really need a proj4string specified unless you are actually doing some spatial operations such as buffers and distances. I take it that you have already considered and discarded the possibility of using using a unique ID for the tax records and after the analysis in R just joining the resulting table in a GIS to your original shapefile. Nikhil On 28 Oct 2009, at 1:33PM, PDXRugger wrote: Hello R Community, I have imported a dataset which contain X Y coordinates and would like to recreate a shape file after some data analysis. What i have done is to import some taxlot data and join them based on some criteria. I want to check to see how well the joining went by reviewing the results in GIS. A couple things. I cant seem to import a shape file correctly using the maptools package and the readShapeSpatial. I have tried Building=file(data/input/BuildingShape/Building.shp) Bldg-readShapeSpatial(fn=data/input/BuildingShape/ Building,proj4string=NAD83) #-- Bldg-readShapeSpatial(data/input/BuildingShape/ Building,proj4string=NAD83) #--- Building=file(data/input/BuildingShape/Building.shp) Bldg-readShapeSpatial(Building,proj4string=NAD83) I know i am mis interpreting the documentation but it doesnt seem like it is very complicated so i am of course confused. Also, i am wondering if i can create a shape file by simply using XY coordinates from a data frame. So for: Ycoord=c( 865296.4, 865151.5, 865457.0 ,865363.4 ,865311.0, 865260.9 ,865210.7 ,865173.3, 865123.6 ,865038.2 ,864841.1 ,864745.4 ,864429.1 ,864795.6 ,864334.9 ,864882.0) Xcoord=c( 4227640 ,4227816 ,4228929 ,4228508 ,4229569 ,4229498 , 4226747, 4226781, 4229597, 4229204, 4228910, 4228959 ,4229465 ,4229794 ,4229596 ,4229082) Lot-c(1900 , 2000, 2100 , 100 ,200 , 300, 400 , 500 , 600 , 701 , 900 , 1000 , 1100, 300 ,100, 200) XYcoord-spCbind(Ycoord,Xcoord) #doesnt work so XYcoord=c(Ycoord,Xcoord) TaxLots-cbind(Ycoord,Xcoord,Lot) writeSpatialShape(XYcoord, TaxLots.., file=data/input/test/Taxlots,strictFilename=FALSE) So help reading in shape files and then creating them using XY coordinates if possible Any help would be appreciated. Thank you. -- View this message in context: http://www.nabble.com/Reading-and-Creating-Shape-Files-tp26098828p26098828.html Sent from the R help mailing list archive at Nabble.com. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
