dictionary - Plotting barchart on States map in R -

following usa states example data state.x77 dataset in r:

mydf = structure(list(usa_state = structure(1:5, .label = c("alabama",  "alaska", "arizona", "arkansas", "california"), class = "factor"),      life.exp = c(69.05, 69.31, 70.55, 70.66, 71.71), hs.grad = c(41.3,      66.7, 58.1, 39.9, 62.6)), .names = c("usa_state", "life.exp",  "hs.grad"), class = "data.frame", row.names = c(na, -5l))  > mydf    usa_state life.exp hs.grad 1    alabama    69.05    41.3 2     alaska    69.31    66.7 3    arizona    70.55    58.1 4   arkansas    70.66    39.9 5 california    71.71    62.6 >  

i want plot on usa states map. can plot map using following code:

all_states <- map_data("state") ggplot() + geom_polygon( data=all_states, aes(x=long, y=lat, group = group),colour="gray", fill="white" ) 

but not able plot barcharts on map. help.

i drew on 2 great sources answer this:

• http://www.r-bloggers.com/us-state-maps-using-map_data/. see gist https://gist.github.com/4252133 , comments @ end @amandamasonsingh (although gists demo prison dataset not available)
• ggplot/mapping counties — problems visualization shapes in r

solution

mydf <- structure(list(usa_state =                           structure(1:5,                                    .label = c("alabama", "alaska", "arizona", "arkansas", "california"), class = "factor"),                        life.exp = c(69.05, 69.31, 70.55, 70.66, 71.71),                        hs.grad = c(41.3, 66.7, 58.1, 39.9, 62.6)),                  .names = c("usa_state", "life.exp", "hs.grad"),                   class = "data.frame", row.names = c(na, -5l))  library(ggplot2) library(maps) library(rcolorbrewer) # lots of color palettes these kind of charts  library(data.table) # sorting key library(mapproj) #coord_maps() needed  all_states <- map_data("state")  # need merge dataset maps 1 long , lat. # need same key lets change state region used in maps all_states # note lowercased match  mydf$region <- tolower(mydf$usa_state) totaldf <- merge(all_states, mydf, = "region")  # switched data.table fix cut map issue # getting sort region order  totaldt <- as.data.table(totaldf) setkey(totaldt, region, order)  ggplot(data = totaldt,         aes(x = long, y = lat, group = group, fill = hs.grad)) +   geom_polygon() + coord_map() +   scale_fill_gradientn("", colours=brewer.pal(9, "gnbu")) 

dont forget sort me

if data not sorted correctly region , order, patchy maps this.

i use data.table package , key data. data.table faster if need merge lots of data. use format x[y] this. see data.table cheatsheet if new package.

final map

this hs.grid in example. other chart changing fill = myvariable

note not states shown, because test data limited these states. in fuller example see more states.

also see alaska missing. not in maps - see this answer @jazzurro practical tests on state names setdiff.