basic map

basicmap.r

doInstall <- TRUE
toInstall <- c("maps", "ggplot2")
if(doInstall){install.packages(toInstall, repos = "http://cran.us.r-project.org")}
lapply(toInstall, library, character.only = TRUE)
library(ggplot2)
library(maps)

Prison <- read.csv("http://www.oberlin.edu/faculty/cdesante/assets/downloads/prison.csv")
head(Prison)

all_states <- map_data("state")
all_states
head(all_states)
Prison$region <- Prison$stateName
Total <- merge(all_states, Prison, by="region")
head(Total)
Total <- Total[Total$region!="district of columbia",]



p <- ggplot()
p <- p + geom_polygon(data=Total, aes(x=long, y=lat, group = group, fill=Total$bwRatio),colour="white"
      ) + scale_fill_continuous(low = "thistle2", high = "darkred", guide="colorbar")
P1 <- p + theme_bw()  + labs(fill = "Black to White Incarceration Rates \n Weighted by Relative Population" 
                            ,title = "State Incarceration Rates by Race, 2010", x="", y="")
P1 + scale_y_continuous(breaks=c()) + scale_x_continuous(breaks=c()) + theme(panel.border =  element_blank())

@jmorten - I couldn't find the prison data - but I used the same code concept for some other data that I was working with. I only listed the code using the Prison data here to stay consistent with the original example.

It appears you can fix the "splintered map/random lines in the map" issue simply by ordering your variables by the "order" variable in all_states after your last merger.
I.e. just insert Total <- Total[order(Total$order),] before running the plotting functions. (see http://stackoverflow.com/questions/23714052/ggplot-mapping-us-counties-problems-with-visualization-shapes-in-r, last answer)

The main difference using the "all = TRUE" argument in the initial merger (Total <- merge(all_states, Prison, all=TRUE)) seems to be that if you DON'T set "all = TRUE" and you are missing data for single states they will be shown as opaque, whereas if you do set "all = TRUE" the states will be inserted but not colored.

Thanks @amandamasonsingh for the code revisions, pointing to the stackoverflow thread, and highlighting the "all = TRUE" issue!