CODEWITHSUNDEEP
rggplot2
larry77
larry77

Reputation: 1533

Unwanted Horizontal Lines in Map Projection in R

A few lines of code to expose my problem. When I work with a map of the world and I introduce a projection, I always end up with some weird looking horizontal lines. Please have a look at https://www.rdocumentation.org/packages/ggplot2/versions/1.0.0/topics/coord_map

from where I take the example for New Zeland

library(ggplot2)

nz <- map_data("nz")
# Prepare a map of NZ
nzmap <- ggplot(nz, aes(x = long, y = lat, group = group)) +
geom_polygon(fill = "white", colour = "black")

# Plot it in cartesian coordinates
nzmap
# With correct mercator projection
nzmap + coord_map()

which works beautifully. Now let us do the same with the world

world <- map_data("world")
# Prepare a map of the world
worldmap <- ggplot(world, aes(x = long, y = lat, group = group)) +
geom_polygon(fill = "white", colour = "black")

# Plot it in cartesian coordinates
worldmap

##but the following is a disaster!
# With correct mercator projection
worldmap + coord_map()

enter image description here I see this issue of the horizontal lines with a projection has been going on for quite a while, but I was able to find only seasoned posts and I had assumed this was fixed long ago. Please find below my sessionInfo. Is there any solution to this? Is it still an open bug?

Upvotes: 4

Views: 2065

Answers (1)

r.bot
r.bot

Reputation: 5424

This is a pretty common problem in ggplot, but happily it is easily fixed:

worldmap + coord_map(xlim=c(-180,180)) producesthis

solution from: Why does coord_map produce a weird output?

Upvotes: 5

Related Questions