gappy gappy - 3 months ago 6
R Question

Plotting color map with zip codes in R or Python

I have some US demographic and firmographic data.

I would like to plot zipcode areas in a state or a smaller region (e.g. city). Each area would be annotated by color and/or text specific to that area. The output would be similar to http://maps.huge.info/ but a) with annotated text; b) pdf output; c) scriptable in R or Python.

Is there any package and code that allows me to do this?

Answer

I am assuming you want static maps.

alt text

1) Get the shapefiles of the zip boundaries and state boundaries at census.gov:

2) Use the plot.heat function I posted in this SO question.

For example (assumes you have the maryland shapefiles in the map subdirectory):

library(maptools)
##substitute your shapefiles here
state.map <- readShapeSpatial("maps/st24_d00.shp")
zip.map <- readShapeSpatial("maps/zt24_d00.shp")
## this is the variable we will be plotting
zip.map@data$noise <- rnorm(nrow(zip.map@data))
## put the lab point x y locations of the zip codes in the data frame for easy retrieval
labelpos <- data.frame(do.call(rbind, lapply(zip.map@polygons, function(x) x@labpt)))
names(labelpos) <- c("x","y")                        
zip.map@data <- data.frame(zip.map@data, labelpos)
## plot it
png(file="map.png")
## plot colors
plot.heat(zip.map,state.map,z="noise",breaks=c(-Inf,-2,-1,0,1,2,Inf))
## plot text
with(zip.map@data[sample(1:nrow(zip.map@data), 10),] , text(x,y,NAME))
dev.off()
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