使用测深数据将ggplot2地图分层到ggmap卫星上 [英] Layering a ggplot2 map onto ggmap satellite with bathymetry data

问题描述

好的，我希望在ggmap基座上绘制一个普通地图，以便海洋显示测深数据.

Okay so I wish to plot a plain map onto the ggmap base so that the ocean shows the bathymetry data.

library(maps)
library(mapdata)
library(ggplot2)
library(ggmap)

#pick out the base layer I want
get.Peru<-get_map(location = c(left = -85, bottom = -20, right = -70, top = -5), maptype="satellite") 

#this is the layer i wish to put over the top
coast_map <- fortify(map("worldHires", fill = TRUE, plot = FALSE)) 

peru_bathy_map <- fortify(get.Peru)

gg <- ggplot() 
gg <- gg + geom_map(data=peru_bathy_map, map=peru_bathy_map,
                    aes(map_id=id))  
gg <- gg + geom_map(data=coast_map, map=coast_map, aes(x=long, y=lat, map_id=region),
                    fill="gray", color="black") + xlim(-86,-70) + ylim(-20,-4) + labs(x="Longitude", y="Latitude") 
gg <- gg + coord_map() +  theme_classic()

但是，我收到错误消息:错误:尝试运行强化代码时，ggplot2不知道如何处理ggmapraster类的数据.

However, I get the error: Error: ggplot2 doesn't know how to deal with data of class ggmapraster when I try and run the fortify code.

我之前曾使用此方法添加测深多边形(请参阅上一个问题)，但是当我将数据点绘制到海洋上时它们看起来很凌乱，所以我现在尝试这样做.

I have used this method before to add bathymetry polygons (see previous question) but they looked messy when I plotted datapoints onto the ocean so I am now trying this.

如果有人有任何指针，甚至还有其他方法来绘制ggmaps卫星以外的看起来干净的测深数据，请让我知道:)

If anyone has any pointers, or even other ways of plotting cleanish looking bathymetry data other that ggmaps satellite please let me know :)

推荐答案

这是一种方法.使用 ggmap 下载地图时，地图的类为 ggmap 和 raster .看来这是您不能应用 fortify 的东西.看到您的代码，我想这也许就是您想要做的.首先，您将获得秘鲁的地图.然后，您将获得数据以绘制灰色的秘鲁地图.在这里，我仅对秘鲁的数据进行了子集化.最后，当我绘制此图时，我使用了 ggmap 和 geom_map .

Here is one approach. When you download maps using ggmap, maps have class ggmap and raster. It seems that this is something you cannot apply fortify. Seeing your code, I think this is perhaps what you want to do. First, you get a map of Peru. Then, you get the data to draw the map for Peru filled with gray colour. Here, I subsetted data for Peru only. Finally, when I drew this figure, I used ggmap and geom_map.

library(mapdata)
library(ggmap)
library(ggplot2)

# Get Peru map
Peru <- get_map(location = "Peru", zoom = 5, maptype="satellite") 

# This is the layer I wish to put over the top
coast_map <- fortify(map("worldHires", fill = TRUE, plot = FALSE)) 

# Subset data for Peru
peru.coast <- subset(coast_map, region == "Peru")

# Draw a graphic
ggmap(Peru) +
geom_map(data = peru.coast, map = peru.coast, aes(x = long, y = lat, map_id = region),
         fill="gray", color="black") +
xlim(-86, -68) +
ylim(-20, 0) + 
labs(x = "Longitude", y = "Latitude") +
coord_map() +
theme_classic()

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