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basic map
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())
@hkaushalya

Thanx for the write up. FYI, CSV file does not exist anymore. But I got what I was looking for.

@yichilychee

Great!

@hubte1g

Thanks!

@mpizosdim

Thank you!Really nice example. I would suggest that first remove the 'district of columbia' and later merge the data. Remove after merging in some datasets give some anomalies to the visualization.

@amandamasonsingh

I had to make a few tweaks to my code to get this to work. (I also forked this gist to show my new code.)

For example, instead of:
Total <- merge(all_states, Prison, by="region")
I had to do:
Total <- merge(all_states, Prison, all=TRUE)

However, after doing that, my map had a bunch of lines running through it. To fix it, I found the following to be helpful (tweaked from http://stackoverflow.com/questions/23714052/ggplot-mapping-us-counties-problems-with-visualization-shapes-in-r):

#*****************
loading packages
#*****************
#for maps
library(maps)
#help(package="maps") #help files if needed

#for plotting data
library(ggplot2)
#help(package="ggplot2") #help files if needed

#this package loads tables faster than merge
library(data.table)
#help(package="data.table") #if you need help with the package later

#to get fancy colors for graphing
#can see some color palettes here: http://moderndata.plot.ly/wp-content/uploads/2015/04/seq-300x211.jpg
library(RColorBrewer)
#help(package="RColorBrewer") #if you need help with the package later

##******************
#Matching state map data frame to Prison data frame
#********************
#setting keys to match the two data frames (all_states and Prison)
all_states <- data.table(map_data('state'))
setkey(all_states,region)
Prison <- data.table(Prison)
setkey(Prison,stateName)
#now merging the two data frames together based on those keys
map.df <- all_states[Prison]

#*************************
#now creating the state map
#**************************
ggplot(map.df, aes(x=long, y=lat, group=group, fill=bwRatio)) +
scale_fill_gradientn("",colours=brewer.pal(9,"GnBu"))+
geom_polygon()+coord_map()+
labs(fill="Black to White Incarceration Rates \n Weighted by Relative Population",
title="State Incarceration Rates by Race, 2010",x="",y="")+theme_bw()

@jmorten

Amanda, where did you find the prison data?

@amandamasonsingh

@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.

@PReineke

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!

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