获取具有指定边界坐标的地图 [英] Get Map with specified boundary coordinates
问题描述
我希望从R获得RgoogleMaps的地图,并且具有特定的坐标边界。
我可以调用GetMap,并指定一个中心,我必须添加缩放级别。一切工作正常,除了我没有得到与我选择的坐标有界的图像映射。
以下是一个例子:
$ b $ (44.49,44.5)
lon <-c(11.33,11.36)
center = c(mean(lat),平均(lon))
zoom< - 14
mmap< - GetMap(center = center,zoom = zoom,maptype =satellite,destfile =m.png)
问题是只有中心被作为参数传递,因此我看到的整个图像取决于缩放水平。所以,我无法真正理解我得到的图像的边界是什么。我想要做的是让图像与我定义的坐标完全一致。这是可能的(也与其他地图包)?
这是一种方法。首先,你得到一个具有一定缩放比例的地图。然后,当您绘制一个图形时,您可以使用 scale_x_continuous
和 scale_y_continuous
来添加lon和lat限制。
library(ggmap)
library(ggplot2)
###设置范围
lat < - c(44.49,44.5)
lon < - c(11.33,11.36)
###获取地图
地图< - get_map(location = c(lon = mean(lon),lat = mean(lat)),zoom = 14,
maptype =satellite,source =google)
# ##绘制图形时,限制lon和lat。
foo < - ggmap(map)+
scale_x_continuous(limits = c(11.33,11.36),expand = c(0,0))+
scale_y_continuous(limits = c(44.49, 44.5),expand = c(0,0))
foo
I want to get a map with RgoogleMaps from R, with a specific coordinates boundary.
What I can call is GetMap, and specify a center, I must add a zoom level. Everything works fine, except that I am not getting an image map bounded with the coordinates I choose.
Here's an example:
lat <- c(44.49,44.5)
lon <- c(11.33,11.36)
center = c(mean(lat), mean(lon))
zoom <- 14
mmap <- GetMap(center = center, zoom=zoom, maptype= "satellite", destfile = "m.png")
The problem is that only the center is passed as a parameter, and thus the whole image I see is dependant on the zoom level. So, I cannot really understand what are the boundaries of the image I get. What I want to do is to get an image bounded exactly with the coordinates I am defining. Is this possible (also with other map packages)?
Here is one way. First, you get a map with a certain zoom. Then, you add the lon and lat limit when you draw a figure, which you can do with scale_x_continuous
and scale_y_continuous
.
library(ggmap)
library(ggplot2)
### Set a range
lat <- c(44.49, 44.5)
lon <- c(11.33, 11.36)
### Get a map
map <- get_map(location = c(lon = mean(lon), lat = mean(lat)), zoom = 14,
maptype = "satellite", source = "google")
### When you draw a figure, you limit lon and lat.
foo <- ggmap(map)+
scale_x_continuous(limits = c(11.33, 11.36), expand = c(0, 0)) +
scale_y_continuous(limits = c(44.49, 44.5), expand = c(0, 0))
foo
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