删除shapefile

Question

我在这里有一个形状文件：https://login.filesanywhere.com/fs/v.aspx?v=8c6c63865a6574bcaa69，我有一个加州红腿青蛙的形状文件，我正在加州的顶部，然而，这些青蛙的范围延伸到加州以外的地方，进入墨西哥。我只想要加州的青蛙数据，我怎样才能修剪扩展到墨西哥的数据呢？我试着使用子集来分隔“原产地”，但它似乎没有任何效果。谢谢你事先提供的帮助。

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library(rgdal)
library(tidyverse)

ranas <- readOGR(dsn = ".", layer = "data_0")
names(ranas)

# Coerce into a dataframe 
ranas4 <- fortify(ranas) 
head(ranas4) 

cali_map <- map_data("state",region="california") 
counties <- map_data("county",region="California")
 head(counties)
 
windows(w=9)
ggplot(cali_map, aes(x = long, y = lat, group = group)) +
geom_polygon() +
geom_polygon(data = ranas4, fill = "green")  

ggplot(cali_map, aes(x = long, y = lat, group = group)) +
geom_polygon(fill = "cornsilk4", col = "cornsilk") +
geom_polygon(data=counties,color="black",fill="lightgoldenrod") +
geom_polygon(data = ranas4, fill = "green", alpha = 0.5) +
theme_void() +
theme(panel.background = element_rect(fill = "cornsilk"))  +
coord_map("albers",lat=90,lat1=80)

# Tried to trim data outside California (Mexico data) with no success.
#I tried: 
ranas2 <- subset(ranas,ORIGIN !=1)
but it doesn't have any effect or subsets anything. 

Answer 1

细分您的空间数据将没有多大用处，因为它的两个特性(行)都不完全在加利福尼亚：

## plot features by origin:
library(ggplot2)
library(sf)

my_shp <- read_sf(dsn = "path_to_shp_directory")

my_shp %>% 
  ggplot() +
  geom_sf() + 
  facet_wrap(~ ORIGIN)

您仍然可以使用带有加利福尼亚边界的(剪辑)功能.：

## make sure both geometries have the same CRS,
## if necessary, by st_transform(your_epsg_code)
my_shp_cropped <- st_crop(my_shp, cali_map)

..。但是请注意，这不会重新计算底层的青蛙数据(例如，只在加利福尼亚计算青蛙数量)。