Question

我正试图描绘我正在阿拉伯/波斯湾研究的某些生物的生态分布。以下是我尝试过的代码示例：

背景层

library(ggplot2)
library(ggmap)

nc <- get_map("Persian Gulf", zoom = 6, maptype = 'terrain', language = "English")
ncmap <- ggmap(nc,  extent = "device")

其他图层

  ncmap+
    stat_density2d(data=sample.data3, aes(x=long, y=lat, fill=..level.., alpha=..level..),geom="polygon")+
    geom_point(data=sample.data3, aes(x=long, y=lat))+
    geom_point(aes(x =50.626444, y = 26.044472), color="red", size = 4)+
    scale_fill_gradient(low = "green", high = "red") + scale_alpha(range = c(0.00, 0.25), guide = FALSE)

但是，我想使用stat_density2d来显示数百种物种（在列中记录，例如SP1 ...... SPn）在水体上的分布，而不仅仅是显示纬度和经度。

另外，是否可以将我的热图限制在水体中？我将感谢您提出的任何帮助和建议

Answer 1

我对你的问题的处理方法是务实的：只需将海湾国家/地区的层放在热图分布上。这相应地构成了热图。但是请注意，热图仍然被计算为好像没有被裁剪。这意味着密度计算不仅限于水体，但它只是视觉上裁剪。

为了重现性，以下代码假定您已解压缩@Hammao提供的.rar文件并在生成的Persian Gulf文件夹中执行代码。

# get sample data
sample.data <- read.csv("sample.data3.csv")

现在，我们需要了解海湾国家的国家形态。我使用rworldmap包。

# loading country shapes
library(rworldmap) 

# download map of the world
worldmap <- getMap(resolution = "high") # note that for 'resolution="high"' 
                                        # you also need the "rworldxtra" pkg

# extract Persian Gulf countries...
gulf_simpl <- worldmap[worldmap$SOVEREIGNT == "Oman" | 
                         worldmap$SOVEREIGNT == "Qatar"  |
                         worldmap$SOVEREIGNT == "United Arab Emirates" |
                         worldmap$SOVEREIGNT == "Bahrain" |
                         worldmap$SOVEREIGNT == "Saudi Arabia" |
                         worldmap$SOVEREIGNT == "Kuwait" |
                         worldmap$SOVEREIGNT == "Iraq" |
                         worldmap$SOVEREIGNT == "Iran", ]

# ... and fortify the data for plotting in ggplot2
gulf_simpl_fort <- fortify(gulf_simpl)

# Now read data for the Persian Gulf, which we need to get the distances for
# the extension of the map
PG <- readOGR(dsn = ".", "iho")
PG <- readShapePoly("iho.shp")

PG <- fortify(PG)

现在，只需按照正确的顺序绘制图层即可。

# generate plot
ggplot(sample.data) + 

  # first we plot the density...
  stat_density_2d(aes(x = long, y = lat, 
                      fill = ..level..),
                  geom="polygon", 
                  alpha = 0.5) +

  # ... then we plot the points
  geom_point(aes(x = long, y = lat)) +

  # gradient options
  scale_fill_gradient(low = "green", high = "red") + 
  scale_alpha(range = c(0.00, 0.25), guide = FALSE) +

  # and now put the shapes of the gulf states on top
  geom_polygon(data = gulf_simpl_fort, 
               aes(x = long, 
                   y = lat, group = group), 
               color = "black", fill = "white", 
               inherit.aes = F) +

  # now, limit the displayed map only to the gulf 
  coord_equal(xlim = c(min(PG_fort$long), max(PG_fort$long)), 
              ylim = c(min(PG_fort$lat), max(PG_fort$lat))) +
  theme_bw()

ggplot_stat_density2d用于生态分布

1 个答案: