在ggmap上覆盖形状文件

Question

我在ggmap上覆盖一个形状文件有问题。

当我单独运行它时，这个形状文件是很好的，见下面的图。

library(ggmap)
library(grid)

la <- get_map(location="Los Angeles County", zoom=9)

# get base map layer
gg <- ggmap(la)

 library(broom)

  LaCountyTracts <- CalifCensusTracts %>% 
   tidy(region = "GEOID") %>%
   filter(grepl("06037", id))

 ggplot(LaCountyTracts, aes(long, lat, group = group) ) +
      geom_polygon(   fill = "grey40", 
           colour = "grey90", alpha = .7, size = .05) +
      coord_map() +
      theme_minimal() 

​

​

下面的代码产生变形的形状层时，ggmap和形状文件被合并。

 gg + geom_polygon(data=LaCountyTracts,aes(x=long, y=lat,group=group),
                      colour = "grey90", alpha = .7, size = .05)

​

​

Answer 1

将线路改为

la <- get_map(location="Los Angeles County", zoom=9)

至

la <- get_map(location="Los Angeles County", zoom = 8)

解决了这个问题