你如何在ggmap中旋转地图的视图？ [英] How do you rotate the view of a map in ggmap?

问题描述

我正在将ggmap对象中的视图从默认的up = true north旋转到我选择的自定义角度，但无法在ggmap或get_map中找到选项。目前，我有以下代码：

  map1<  -  get_map（location = c（-78.872209，35.050514），zoom = 17，maptype =hybrid）
 ggmap（map1）
  

产生：

我想旋转图像，以便显示的主要街道（人街）垂直对齐，就像这样（我刚刚在screencapture软件中手动旋转）：

我的目标当然是仍然有一个水平和垂直的x和y轴作为原始图像，但有实际的视口旋转。

解决方案

在旋转的（和重新调整大小的）视口中绘制地图，但在相反的方向旋转标签。 lon标签的位置（hjust，vjust）需要稍微调整。如果旋转角度不太大，调整就可以了。

 库（ggmap）
库（网格）
 
＃获取地图$ b $ c $（$）
 lat <-c（-47.5，-33.5）
 map1 < -  get_map（location = c（-78.872209,35.050514），zoom = 17，maptype =hybrid）
 
＃旋转角度
 rotate = -67 
 
＃向相反方向旋转标签
＃加上对刻度标记位置的调整
 map = ggmap（map1）+ 
 theme（axis.text.x = element_text（angle = -rotate，
 vjust = 1.1，hjust =旋转> 0，0,1）），
 axis.text.y = element_text（angle = -rotate），
 axis.title.y = element_text（angle = -rotate，vjust = 0.5），
 axis.title.x = element_text（angle = -rotate））
 
＃在旋转的视口中绘制地图，调整大小
 print（map ，vp = viewport（width = .7，height = .7，angle = rotate））
  

< a href =https://i.stack.imgur.com/nLe 7i.pngrel =nofollow noreferrer>

I am looking to rotate the view within the ggmap object from the default of up = true north, to a custom angle of my choosing, but can't find the option within ggmap or get_map. Currently, I have the following code:

map1 <- get_map(location=c(-78.872209, 35.050514), zoom = 17, maptype="hybrid")
ggmap(map1)

Which produces:

I would like to rotate the image so that the main street shown (Person Street) is vertically-aligned, like this (which I just rotated manually in a screencapture software):

My goal, of course, is to still have a horizontal and vertical x and y axis as the original image, but have the actual "viewport" be rotated.

解决方案

Draw the map in a rotated (and re-sized) viewport, but rotate the labels in the opposite direction. The position (hjust, vjust) of the lon labels needs a little adjustment. If the angle of rotation isn't too big, the adjustment is okay.

library(ggmap)
library(grid)

# Get the map
lon <- c(165, 180)
lat <- c(-47.5, -33.5) 
map1 <- get_map(location = c(-78.872209, 35.050514), zoom = 17, maptype = "hybrid")

# Angle of rotation
rotate = -67

# Rotate the labels  in the opposite direction,
# plus an adjustment of the position of the tick mark labels 
map = ggmap(map1) +
      theme(axis.text.x = element_text(angle= -rotate, 
                            vjust = 1.1, hjust = ifelse(rotate > 0, 0, 1)),
            axis.text.y = element_text(angle = -rotate),
            axis.title.y = element_text(angle = -rotate, vjust = 0.5),
            axis.title.x = element_text(angle = -rotate))

# Draw the map in a rotated viewport, with its size adjusted
print(map, vp = viewport(width = .7, height = .7, angle = rotate))

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