How keep information from shapefile after fortify()

Question

How can I keep polygons\'s information after shapefile? Let me try to explain:

I have a shapefile with this data:

> head(mapa@data)
         ID      C         


        

Answer 1

Since you did not provide your shapefile or data, it's impossible to test, but something like this should work:

# not tested...
library(plyr)      # for join(...)
library(rgdal)     # for readOGR(...)
library(ggplot2)   # for fortify(...)

mapa <- readOGR(dsn=".",layer="shapefile name w/o .shp extension")
map@data$id <- rownames(mapa@data)
mapa@data   <- join(mapa@data, data, by="CD_GEOCODI")
mapa.df     <- fortify(mapa)
mapa.df     <- join(mapa.df,mapa@data, by="id")

ggplot(mapa.df, aes(x=long, y=lat, group=group))+
  geom_polygon(aes(fill=Population))+
  coord_fixed()