Message-ID: <f7bd71731001062243p144707b8m23a5c4cd9314b3d5@mail.gmail.com>
Date: 2010-01-07T06:43:49Z
From: Noli Sicad
Subject: subsetting shapefile polygons with separate table criteria
# Subseting shapefile before merging tables - join table
I realised that deleting the polygon with does match wit the record is
not possible since, I can read the shapefile at all. But still I need
to know how to delete / subset polygons.
I think this is more workable.
1. Read shapefile polygons from foreststand.shp
2. Match harvest.dbf table with polygon ID foreststand.shp
3. Subset shapefile polygon that matches
4. Write subset into a new shapefile
~~~~~~~~~~~
getwd()
setwd('C:\\Down2\\R_forestmgt\\modelIII\\')
library(rgdal)
library(maptools)
#forest <- readOGR(".", "ForestStand")
forest <- readShapePoly("ForestStand")
harvest< read.csv('forest_cut.csv')
#Match
index <- match(harvest$CROP_ID, forest$CROP_ID , nomatch = 0)
# subset polygon.
# use this index here for setting
mypoly <- subset(forest, Index)
#Save shapefile
writeOGR(mypoly, ".", "ForestStandNew", "ESRI Shapefile")
~~~~~~~~~~~~
Any ideas how to do this?
Thanks in advance.
Noli