ggplot US state map; colors are fine, polygons jagged - r

13,870

You don't need to do the merge. You can use geom_map and keep the data separate from the shapes. Here's an example using the built-in USArrests data (reformatted with dplyr):

library(ggplot2)
library(dplyr)

us <- map_data("state")

arr <- USArrests %>% 
  add_rownames("region") %>% 
  mutate(region=tolower(region))

gg <- ggplot()
gg <- gg + geom_map(data=us, map=us,
                    aes(x=long, y=lat, map_id=region),
                    fill="#ffffff", color="#ffffff", size=0.15)
gg <- gg + geom_map(data=arr, map=us,
                    aes(fill=Murder, map_id=region),
                    color="#ffffff", size=0.15)
gg <- gg + scale_fill_continuous(low='thistle2', high='darkred', 
                                 guide='colorbar')
gg <- gg + labs(x=NULL, y=NULL)
gg <- gg + coord_map("albers", lat0 = 39, lat1 = 45) 
gg <- gg + theme(panel.border = element_blank())
gg <- gg + theme(panel.background = element_blank())
gg <- gg + theme(axis.ticks = element_blank())
gg <- gg + theme(axis.text = element_blank())
gg

enter image description here

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13,870
Keyboard Frenzy
Author by

Keyboard Frenzy

Updated on August 07, 2022

Comments

  • Keyboard Frenzy
    Keyboard Frenzy over 1 year

    I'm trying to plot a US map where each state is shaded by the count that it has. I've gotten the shading to work just fine. The problem I'm running into, however, is that the polygons look very jagged (I'm assuming something happened when I tried to merge the map_data('state') with my data frame of counts per state). My data frame before merging has 49 rows (Nevada was missing data in my set), and after merging has many more rows (expected for the long/lat items for the states) but the data appears to be copied correctly for each lat/long pair, so I'm unsure why the poly's are so jagged.

    Code:

    ggplot() +
      geom_polygon(data=try1, aes(x=long, y=lat, group = group, fill= COUNT)) +
      scale_fill_continuous(low='thistle2', high='darkred', guide='colorbar') +
      theme_bw() + labs(fill="State Map Try Title1", title='Title2', x='', y='') +
      scale_y_continuous(breaks=c()) +
      scale_x_continuous(breaks=c()) +
      theme(panel.border = element_blank())
    

    Any help would be greatly appreciated (and obviously, if there is a better way to do it, I'm open to suggestions!).

    enter image description here

  • Keyboard Frenzy
    Keyboard Frenzy almost 9 years
    Hey thanks! This works as well. I especially appreciate the coord_map since it makes the map a bit more pretty.
  • Superbest
    Superbest almost 8 years
    I can't get this to run. First %>% is not available by default and hard to google for (it's from magrittr). Second I can't get dplyr to install on 3.1.1. Can you edit the column shuffling to be more minimal?
  • hrbrmstr
    hrbrmstr almost 8 years
    The code runs perfectly in a vanilla R session and %>% comes along for the ride with dplyr. Which means you didn't run it as-is. Also, I'm sure you are more than capable of putting the code into your own editor and changing line spacing/indenting to suit your personal preferences, @Superbest
  • Superbest
    Superbest almost 8 years
    Well it didn't work for me, I use Rstudio. Column shuffling refers to columns of data frame, not the source. Anyway, excuse me for trying to help improve the answer.
  • hrbrmstr
    hrbrmstr almost 8 years
    You did not execute the code the way it is written. Period. I use RStudio as well.
  • Achekroud
    Achekroud over 7 years
    Code works perfectly if you follow it with a new & clean install. Thanks @hrbrmstr. One additional helper in case people are looking for alternative colour palettes, the following will go from blue to red through white: scale_fill_gradientn(colours = c("#2b8cbe", "white", "#d7301f"))
  • hrbrmstr
    hrbrmstr over 7 years
    You should absolutely not do that color palette. 10% of the world can't see it properly. Look at the viridis package. I only used the colors the OP had since it was what the OP had.