library(ggplot2)
library(maps)
library(mapproj)

# read in points
mpc <- read.csv("meancentersWGS.csv")

# plot the means, grouped by population subgroup
p <- qplot(MEAN_X, MEAN_Y, data=mpc, colour=factor(POP), size=I(1.2), xlab="", ylab="", main="US Mean Population Centers 1790-2000")

# use eastern section of US as basemap
us.east = c("minnesota","iowa","missouri","arkansas","louisiana","wisconsin","illinois","tennessee","michigan","maine","indiana","kentucky","alabama","ohio","georgia","massachusetts","vermont","new hampshire","mississippi","rhode island","new york","conneticut","pennsylvania","new jersey","deleware","west virginia","virginia","maryland","north carolina","south carolina","florida")
p <- p + borders("state", region=us.east, size=0.2, colour = I("grey65"))

# transform coordinates into Albers Equal Area
p <- p +  coord_map(project="albers", lat0=37.5, lat1=29.5)

# add path for all three population groups
p <- p + geom_path(size=0.2)

# make legend and colors nicer
p <- p + scale_colour_brewer(pal="Set1", name = "Population Group", breaks=c("African-African/American", "Enslaved", "Total"), labels =c("African, African-American", "Enslaved (1790-1860)", "Total (1790-2000)"))

# add labels for 1790..
p <- p + annotate("text", x = subset(mpc, POP == "African-African/American")[1,2], y = subset(mpc, POP == "African-African/American")[1,3], label = subset(mpc, POP == "African-African/American")[1,1], size=2.5, hjust = 0.4, vjust = -0.5)
# ... 2000..
p <- p + annotate("text", x = subset(mpc, POP == "African-African/American")[length(subset(mpc, POP == "African-African/American")),2], y = subset(mpc, POP == "African-African/American")[nrow(subset(mpc, POP == "African-African/American")),3], label = subset(mpc, POP == "African-African/American")[nrow(subset(mpc, POP == "African-African/American")),1], size=2.5, hjust = 3.5, vjust = -1)
# ... and 1900
p <- p + annotate("text", x = subset(subset(mpc, POP == "African-African/American"), CENSUSYR == 1900)[1,2], y = subset(subset(mpc, POP == "African-African/American"), CENSUSYR == 1900)[1,3], label = subset(subset(mpc, POP == "African-African/American"), CENSUSYR == 1900)[1,1], size=2.5, hjust = 1.2, vjust = 1)

# plot it!
pdf()
p
dev.off()