CODEWITHSUNDEEP
rgispolygonpoint
user3005718
user3005718

Reputation: 23

N/A values using over() function with sp package in R

I'm relatively new to GIS and R, and I'm do a project to map crime data to specific neighborhoods in cities. The data file is in CSV format, with incident ID, longitude and latitude. The neighborhood polygons are defined by shapefile. Here is my code in R:

require(sp)  
require(rgdal)
require(maps)

crime<-read.csv("crime sample.csv")
crime<-subset(crime,!is.na(crime$Latitude))
coordinates(crime)<-c("Longitude","Latitude")
Neigh <- readOGR(".", "Neighborhoods_2012b")

proj4string(crime)<-proj4string(Neigh)
inside.Neigh <- !is.na(over(crime, as(Neigh, "SpatialPolygons")))

however, the result shows that there are no points that falls within any of the polygons. 

proj4string(Neigh)

gives

[1] "+proj=tmerc +lat_0=36.66666666666666 +lon_0=-88.33333333333333 +k=0.999975          
+x_0=300000 +y_0=0 +datum=NAD83 +units=us-ft +no_defs +ellps=GRS80 +towgs84=0,0,0

The data files used are available at this link: file

thanks for any help.

Upvotes: 2

Views: 2428

Answers (1)

rcs
rcs

Reputation: 68849

You have to re-project one data set. The spTransform methods provide transformation between datum(s) and conversion between projections:

Neigh_wgs84 <- spTransform(Neigh, CRS("+proj=longlat +datum=WGS84"))
proj4string(crime) <- proj4string(Neigh_wgs84)
plot(Neigh_wgs84)
plot(crime, add=TRUE, col="red")

plot

R> over(crime, Neigh_wgs84)
        PRI_NEIGH                SEC_NEIGH SHAPE_AREA SHAPE_LEN
1       Gage Park MARQUETTE PARK,GAGE PARK   61284896     32294
2   Humboldt Park            HUMBOLDT PARK  125010426     46127
3 Grand Boulevard              BRONZEVILLE   48492503     28197
4  Garfield Ridge           MIDWAY AIRPORT  117890778     60080
5  Auburn Gresham           AUBURN GRESHAM  105065354     46758

Upvotes: 5

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