Hello all,
I am working on mapping the density of calls for service for our police department in my town. Please excuse me because I'm completely self-teaching R, so I'm probably pretty inefficient in my programming. Also, this is probably a simple answer, so I apologize for that, but I hope someone can help. The data that I have indicates the address of the call for service and I am interested in aggregating to regions of the town so that I can create a heat map that shows where in the town there are higher demands for service for police. My strategy thus far has been to geocode the address points, then to create a grid structure over the town, and then overlay the points to assign them to a grid. Then, I would like to calculate the frequency of which a cell has calls for service within it and create a heat map of the high density demand locations. Then, I'd like to map it with an overlay of the town streets (which I can do). Can anyone help on where to do next? I can calculate frequencies after I've converted the overlay output into a data frame, but I'm not sure how to add that in as like an attribute to the Spatial Polygon structure that I've created. I think this is almost like a join when you're using ArcMap, but I'm not sure how to have that third variable for each cell and then plot it with appropriate color codes. Any ideas on how to get to the next point? Here is some of the code I've done so far, which has gotten me to the point that I've geocoded the addresses, created a grid-like spatial polygon, and then overlayed the points to the polygon, then created the df for the overlay. library(gdata) library(ggmap) library(dismo) library(XML) library(PBSmapping) library(rgeos) library(sp) library(gstat) cfs<-read.xls("cfs.xlsx", sheet="Sheet1") ##create grid grid<-GridTopology(c(-78.55, 38.85), c(0.0012, 0.0010), c(50,50)) grid.points<-SpatialPoints(grid) grid.pixels<-SpatialPixels(grid.points) poly<-as(grid.pixels, "SpatialPolygons") plot(poly, col="white", border="grey", axes=T) ## geocode addresses and plot add<-geocode(cfs$location.address, oneRecord=FALSE) coordinates(add)<-c("longitude", "latitude") plot(add, col="red", axes=T, add=T, pch=21) ##overlay incidents to grid over<-overlay(poly,add) over.df<-data.frame(over) Thanks, Reid Reid A. Wodicka | Town Manager Town of Woodstock, Virginia 135 North Main Street | Woodstock, Virginia 22664 Phone: 540-459-3621 | Fax: 540-459-3085 <mailto:reid.wodi...@townofwoodstockva.gov> reid.wodi...@townofwoodstockva.gov | <http://www.townofwoodstockva.gov> http://www.townofwoodstockva.gov <http://www.facebook.com/pages/Town-of-Woodstock-Virginia/201011663375674> To find out the latest information, LIKE US on Facebook!
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