Convert map data to data frame using fortify {ggplot2} for spatial objects in R

Question

I use to be able to run this script without any problem, but now the fortify {ggplot2} command gives me an error message. Any hint of what might be the problem would be grea

Answer 1

I got it to work in ggplot2 and here is how I did it with the version and session info at the bottom.

The Map in ggplot2

The Code

rm(list = ls(all = TRUE)) #clear workspace

library(maptools)
library(gpclib)
library(ggplot2)

shape<-readShapeSpatial("./fao/World_Fao_Zones.shp") 
shape@data$id <- rownames(shape@data)
shape.fort <- fortify(shape, region='id') 
shape.fort<-shape.fort[order(shape.fort$order), ] 
ggplot(data=shape.fort, aes(long, lat, group=group)) + 
    geom_polygon(colour='black',
                 fill='white') +
    theme_bw()

The Session

> sessionInfo()
R version 2.15.0 (2012-03-30)
Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit)

locale:
    [1] C/en_US.UTF-8/C/C/C/C

attached base packages:
    [1] grid      stats     graphics  grDevices utils    
[6] datasets  methods   base     

other attached packages:
    [1] mapproj_1.1-8.3 gpclib_1.5-1    maptools_0.8-14
[4] lattice_0.20-6  foreign_0.8-49  rgeos_0.2-5    
[7] stringr_0.6     sp_0.9-99       gridExtra_0.9  
[10] mapdata_2.2-1   ggplot2_0.9.0   maps_2.2-5     

loaded via a namespace (and not attached):
    [1] MASS_7.3-17        RColorBrewer_1.0-5 colorspace_1.1-1  
[4] dichromat_1.2-4    digest_0.5.2       memoise_0.1       
[7] munsell_0.3        plyr_1.7.1         proto_0.3-9.2     
[10] reshape2_1.2.1     scales_0.2.0       tools_2.15.0

Answer 2

Fortify is likely to be deprecated. A new alternative is broom (see documentation here). It is very simply to use:

# Load shapefile
FAO <- readOGR(dsn="fao", layer="World_Fao_Zones")
#Convert
FAO_df <- tidy(FAO)

Unfortunately, the file you uploaded is not there anymore, so I cannot demonstrate the command for your example.