ggplot map with l

Question

I want to plot a world map using ggplot2 (v.9) which combines two pieces if information. The following example illustrates:

library(rgdal) library(ggplot2) library(maptools)  # Data from http://thematicmapping.org/downloads/world_borders.php. # Direct link: http://thematicmapping.org/downloads/TM_WORLD_BORDERS_SIMPL-0.3.zip # Unpack and put the files in a dir 'data'  gpclibPermit() world.map <- readOGR(dsn="data", layer="TM_WORLD_BORDERS_SIMPL-0.3") world.ggmap <- fortify(world.map, region = "NAME")  n <- length(unique(world.ggmap$id)) df <- data.frame(id = unique(world.ggmap$id),                  growth = 4*runif(n),                  category = factor(sample(1:5, n, replace=T)))  ## noise df[c(sample(1:100,40)),c("growth", "category")] <- NA   ggplot(df, aes(map_id = id)) +      geom_map(aes(fill = growth, color = category), map =world.ggmap) +      expand_limits(x = world.ggmap$long, y = world.ggmap$lat) +      scale_fill_gradient(low = "red", high = "blue", guide = "colorbar") 

However, this solution is not a nice way to display both growth and category. Growth is highly visible, but category is almost impossible to see because it is just a border.

I have tried to increase the size of borders, but without luck (the new geom_map is hard to work with). Does anyone knows how to increase border size in the above example, or even better, a mechanism to display two factors?

A bonus question: country names, such as those used by the maps package (which features USSR!) are the data used in the example is fragile. I prefer to use ISO 3166-1 alpha-3(1). Does anyone know data readily usable with ggplot2 which features ISO-... country names (included in linked data)

Result:

result http://ompldr.org/vY3hsYQ

Answer 1

I would use different hue ranges for fill and line color:

ggplot(df, aes(map_id = id)) +   geom_map(aes(fill = growth, color = category), map =world.ggmap) +   expand_limits(x = world.ggmap$long, y = world.ggmap$lat) +   scale_fill_gradient(high = "red", low = "white", guide = "colorbar") +   scale_colour_hue(h = c(120, 240)) 

OR, use fill for category and transparency for growth level.

ggplot(df, aes(map_id = id)) +   geom_map(aes(alpha = growth, fill = category), map =world.ggmap) +   expand_limits(x = world.ggmap$long, y = world.ggmap$lat) +   scale_alpha(range = c(0.2, 1), na.value = 1) 

It depends on what you want to show.

Just in case, here is the way to change the linesize:

ggplot(df, aes(map_id = id)) +  geom_map(aes(fill = growth, color = category, size = factor(1)), map =world.ggmap) +  expand_limits(x = world.ggmap$long, y = world.ggmap$lat) +  scale_fill_gradient(high = "red", low = "white", guide = "colorbar") +  scale_colour_hue(h = c(120, 240)) +   scale_size_manual(values = 2, guide = FALSE) 

Here is HSV version:

df$hue <- ifelse(is.na(df$category), 0, as.numeric(df$category)/max(as.numeric(df$category), na.rm=T)) df$sat <- ifelse(is.na(df$growth), 0, df$growth/max(df$growth, na.rm=T)) df$fill <- ifelse(is.na(df$category), "grey50", hsv(df$hue, df$sat))  ggplot(df, aes(map_id = id)) +  geom_map(aes(fill = fill), map =world.ggmap) +  expand_limits(x = world.ggmap$long, y = world.ggmap$lat) +  scale_fill_identity(guide = "none") 

Answer 2

One option is to map growth to the size of some points plotted at the centroid of the polygons.

centroids <- as.data.frame(coordinates(world.map)) df <- data.frame(df,centroids)  choropleth <-ggplot() +      geom_map(aes(fill = category, map_id = id),data = df, map =world.ggmap) +      expand_limits(x = world.ggmap$long, y = world.ggmap$lat) +      scale_fill_hue(na.value=NA) choropleth    choropleth + geom_point(aes(x=V1,y=V2,size=growth),data=df) +     scale_area(range=c(0,3)) 

Or if you really want to double code color, you could color the points instead. Note, that you can also add a raster map of satellite imagery with the new OpenStreetMap package (shameless plug).

library(OpenStreetMap) library(raster) rastermap <- openmap(c(70,-179),         c(-70,179),zoom=2,type='bing') rastermap <- openproj(rastermap) autoplot(rastermap,expand=FALSE) +      geom_map(aes(x=70,y=70,fill = category, map_id = id),data = df,         map =world.ggmap) +      expand_limits(x = world.ggmap$long, y = world.ggmap$lat) +      scale_fill_hue(na.value=NA) +      geom_point(aes(x=V1,y=V2,colour=growth),data=df) +     scale_colour_gradient(low = "red", high = "blue",          guide = "colorbar",na.value=NA)