[R-sig-Geo] noob question: access single region from .shp file
Brandon Payne
payneb at post.bgu.ac.il
Wed Mar 8 14:45:45 CET 2017
How do you access a single region in a shape file?
<begin pseudo code:>
if (Israelshape2$NAME_1=="Golan") {
Color= "Red"}
</end>
<begin real code:>
#! /usr/bin/R
## grab shape file
download.file("http://biogeo.ucdavis.edu/data/diva/adm/ISR_adm.zip",
"./includes/ISR_adm.zip")
unzip("./includes/ISR_adm.zip", files=Sys.glob(".shp"),
unzip="internal", exdir = "./shapeFiles")
## libraries
library(maptools)
library(RColorBrewer)
colors <- brewer.pal(9, "BuGn")
library(ggmap)
## google maps
mapImageData3 <- get_map(location = c(lon = 35.1660235,
lat = 31.32226),
color="color",
source = "google",
maptype = "satellite",
zoom = 7)
## read shape file
IsraelPolygon <- readShapePoly("./includes/ISR_adm/ISR_adm1.shp")
IsraelPoints <- fortify(IsraelPolygon)
## plot shapes on top of map, output to graphics device
ggmap(mapImageData3,
extent = "device",
ylab = "Latitude",
xlab = "Longitude") +
geom_polygon(aes(x=long,
y=lat,
group=group),
data=IsraelPoints,
color=colors[9],
fil= colors[6],
alpha=0.5) +
labs(x="Longitude",
y="Latitude")
#############################
ILshape2 <- rgdal::readOGR(dsn="./includes/ISR_adm", layer="ISR_adm1")
rgdal::readOGR(dsn="./includes/ISR_adm", layer="ISR_adm1",
disambiguateFIDs = TRUE)
</end>
>> output:graphic: map w/ lightly colored polygons overlayed.
>> output:text:
OGR data source with driver: ESRI Shapefile
Source: "./includes/ISR_adm", layer: "ISR_adm1"
with 7 features
It has 9 fields
An object of class "SpatialPolygonsDataFrame"
Slot "data":
ID_0 ISO NAME_0 ID_1 NAME_1 TYPE_1 ENGTYPE_1 NL_NAME_1
0 111 ISR Israel 1 Golan Mehoz District <NA>
1 111 ISR Israel 2 HaDarom Mehoz District <NA>
2 111 ISR Israel 3 Haifa Mehoz District <NA>
3 111 ISR Israel 4 HaMerkaz Mehoz District <NA>
4 111 ISR Israel 5 HaZafon Mehoz District <NA>
5 111 ISR Israel 6 Jerusalem Mehoz District <NA>
6 111 ISR Israel 7 Tel Aviv Mehoz District <NA>
VARNAME_1
0 <NA>
1 Southern District
2 Hefa
3 Central District
4 Northern
5 Al-Quds|Yerushalayim
6 <NA>
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