在ggplot2中绘制地图时避免水平线和疯狂的形状 [英] Avoiding hoizontal lines and crazy shapes when plotting maps in ggplot2

问题描述

我想要一个区域的阴谋，例如拉丁美洲，使用来自IPUMSI的世界形状文件...

当我想专注于拉丁美洲我得到了一些不需要的水平线：

$ $ $ $ $ $ $ $ $ ggplot（data = df0，mapping = aes（x = long，y = lat ，group = group））+
geom_polygon（fill =black，color =black）+
coord_map（xlim = c（-125，-30），ylim = c（-60， 35））

我尝试使用 clipPolys 函数来解决此问题，请遵循

对这个情节也不是很满意。我认为这是一个漏洞问题，就像这个问题一样，但是建议的解决方案会产生与上面相同的图：

  gghole < - 函数（fort）{
 poly < -  fort [fort％ [$ fort $洞，$ $ id，] 
洞<  - 堡垒[！堡垒$ id％在堡垒[堡垒$洞，] $ id，] 
出<  - 列表）
名（out）< -c（'poly'，'hole'）
 return（out）
} 
 
 ggplot（df2，aes（x = long，y = lat，group = group））+ 
 geom_polygon（data = gghole（df2）[[1]]，fill =black，color =black）+ 
 geom_polygon data = gghole（df2）[[2]]，fill =black，color =black）
 
 ggplot（df0，aes（x = long，y = lat，group = group） ）+ 
 geom_polygon（data = gghole（df0）[[1]]，fill =black，color =black）+ 
 geom_polygon（data = gghole（df0）[[2]] ，fill =black，color =black）+ 
 coord_map（xlim = c（-125，-30），ylim = c（-60，35））
  

解决方案

 库（ggplot2）
库（maptools）
库（mapproj）
 
＃Maptools数据集
数据（wrld_simpl ）
 world < -  fortify（wrld_simpl）
 
＃同样的情节，但限制视图而不是删除点
＃允许完成渲染
 ggplot（世界，mapping = aes（x = long，y = lat，group = group））+ 
 geom_polygon（fill =black，color =black）+ 
 coord_cartesian（xlim = c（ - 125，-30），ylim = c（-60，35））
  

I want a plot of an area, such as Latin America, using the world shape file from IPUMSI...

https://international.ipums.org/international/resources/gis/IPUMSI_world.zip

... I will add some more IPUMS districts later so I really want to use this as my template layer.

I having difficulty with the plot when I add limits through coord_map in ggplot2.

The initial spatial file looks alright

library("ggplot2")
library("raster")

sd0 <- readShapePoly("./IPUMSI_world.shp")
df0 <- fortify(sd0)

ggplot(data = df0, mapping = aes(x = long, y = lat, group = group)) +
  geom_polygon(fill = "black", colour = "black")

When I want to focus on Latin America I get some unwanted horizontal lines:

ggplot(data = df0, mapping = aes(x = long, y = lat, group = group)) +
  geom_polygon(fill = "black", colour = "black") +
  coord_map(xlim = c(-125, -30), ylim = c(-60, 35))

I tried to fix this using the clipPolys function, following the guidance here

library("PBSmapping")
df1 <- df0
names(df1)[c(1,2,6,3)] <- c("X","Y","PID","POS")
df1$PID <- as.numeric(df1$PID)
df2 <- clipPolys(polys = df1, xlim = c(-125, -30), ylim = c(-60, 35), keepExtra = TRUE)
names(df2)[names(df2)=="X"] <- "long" 
names(df2)[names(df2)=="Y"] <- "lat"
names(df2)[names(df2)=="PID"] <- "id"

ggplot(data = df2, mapping = aes(x = long, y = lat, group = group)) +
  geom_polygon(fill = "black", colour = "black") 

Not really super happy with this plot either. I thought it was a problem with holes, as in this question, but the suggested solution produces the same plots as above:

gghole <- function(fort){
  poly <- fort[fort$id %in% fort[fort$hole,]$id,]
  hole <- fort[!fort$id %in% fort[fort$hole,]$id,]
  out <- list(poly,hole)
  names(out) <- c('poly','hole')
  return(out)
} 

ggplot(df2, aes(x=long, y=lat, group=group)) +
  geom_polygon(data = gghole(df2)[[1]], fill = "black", colour = "black") +
  geom_polygon(data = gghole(df2)[[2]], fill = "black", colour = "black")

ggplot(df0, aes(x=long, y=lat, group=group)) +
  geom_polygon(data = gghole(df0)[[1]], fill = "black", colour = "black") +
  geom_polygon(data = gghole(df0)[[2]], fill = "black", colour = "black") +
  coord_map(xlim = c(-125, -30), ylim = c(-60, 35))

解决方案

The other solution is to restrict the view, rather than remove point from the render:

library(ggplot2)
library(maptools)
library(mapproj)

# Maptools dataset
data(wrld_simpl)
world <- fortify(wrld_simpl)

# Same plot, but restrict the view instead of removing points
# allowing the complete render to happen
ggplot(world, mapping = aes(x = long, y = lat, group = group)) +
  geom_polygon(fill = "black", colour = "black") +
  coord_cartesian(xlim = c(-125, -30), ylim = c(-60, 35))

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