Region missing parts of map in ggplot2 in R

Question

I am trying to make a heatmap for states in the United States using ggplot2 in R. When I do so, I run into this same problem as detailed in this and this post, however the solution - to specify a left join using merge or to use dplyr::left_join or dplyr::inner_join do not seem to work.

Here's what I did to create the following plot, with part of Washington, New Jersey, New York missing or the wrong color, using data in my_data, which is below the plot:

library(ggplot2)
library(ggthemes)

str(my_data)

> str(data)
'data.frame':   50 obs. of  2 variables:
 $ region          : chr  "alaska" "alabama" "arkansas" "arizona" ...
 $ number_of_tweets: int  0 10967 5130 462 26489 267 1464 2431 9777 7359 ...

states <- map_data("state")

choro <- dplyr::left_join(states, my_data, by = "region")

ggplot() +
      geom_polygon(data = choro, 
                   aes(x = long, y = lat, group = region, fill = number_of_tweets)) +
      scale_fill_gradient(low = "#deebf7", high = "#3182bd") +
      theme_map()

Here is the contents of my_data in case this helps reproducibility:

region,number_of_tweets
alabama,10929
alaska,0
arkansas,5107
arizona,452
california,26299
colorado,265
connecticut,1459
delaware,2418
florida,9666
georgia,7306
hawaii,2486
iowa,29229
idaho,7607
illinois,10221
indiana,20700
kansas,32252
kentucky,11098
louisiana,938
massachusetts,10764
maryland,4091
maine,5770
michigan,47335
minnesota,1079
missouri,1079
mississippi,1273
montana,11606
north carolina,22354
north dakota,6294
nebraska,7319
new hampshire,7185
new jersey,26850
new mexico,0
nevada,7918
new york,16007
ohio,8284
oklahoma,63551
oregon,1120
pennsylvania,908
rhode island,10240
south carolina,6296
south dakota,3559
tennessee,4765
texas,30235
utah,15019
virginia,5541
vermont,16444
washington,7506
wisconsin,7817
wyoming,10496
west virginia,0

Answer 1

No need for the data joining or a horrible projection. Note, your data is really not continuous and you should figure out how you should normalize it (probably find the estimated # of twitter users per state and normalize it by that, or use per 100,000 population).

library(ggplot2)
library(ggthemes)
library(viridis)

my_data <- structure(list(region = c("alabama", "alaska", "arkansas", "arizona", 
"california", "colorado", "connecticut", "delaware", "florida", 
"georgia", "hawaii", "iowa", "idaho", "illinois", "indiana", 
"kansas", "kentucky", "louisiana", "massachusetts", "maryland", 
"maine", "michigan", "minnesota", "missouri", "mississippi", 
"montana", "north carolina", "north dakota", "nebraska", "new hampshire", 
"new jersey", "new mexico", "nevada", "new york", "ohio", "oklahoma", 
"oregon", "pennsylvania", "rhode island", "south carolina", "south dakota", 
"tennessee", "texas", "utah", "virginia", "vermont", "washington", 
"wisconsin", "wyoming", "west virginia"), number_of_tweets = c(10929L, 
0L, 5107L, 452L, 26299L, 265L, 1459L, 2418L, 9666L, 7306L, 2486L, 
29229L, 7607L, 10221L, 20700L, 32252L, 11098L, 938L, 10764L, 
4091L, 5770L, 47335L, 1079L, 1079L, 1273L, 11606L, 22354L, 6294L, 
7319L, 7185L, 26850L, 0L, 7918L, 16007L, 8284L, 63551L, 1120L, 
908L, 10240L, 6296L, 3559L, 4765L, 30235L, 15019L, 5541L, 16444L, 
7506L, 7817L, 10496L, 0L)), .Names = c("region", "number_of_tweets"
), class = "data.frame", row.names = c(NA, -50L))

states <- map_data("state")

my_data$cut <- as.character(cut(my_data$number_of_tweets, 
                                breaks=pretty(x=my_data$number_of_tweets, n=7),
                                labels=pretty(x=my_data$number_of_tweets, n=7)[-1]))

my_data$cut <- ifelse(is.na(my_data$cut), 0, my_data$cut)

gg <- ggplot()
gg <- gg + geom_map(data=states, map=states,
                    aes(x=long, y=lat, map_id=region),
                    color="white", size=0.1, fill=NA)
gg <- gg + geom_map(data=my_data, map=states,
                    aes(fill=cut, map_id=region),
                    color="white", size=0.1)
gg <- gg + scale_fill_viridis(name="# Tweets", discrete=TRUE, begin=0.1, end=0.9)
gg <- gg + coord_map("polyconic")
gg <- gg + theme_map()
gg <- gg + theme(legend.position="right")
gg