重温“在 ggplot 中格式化纬度和经度轴标签”

Question

问题/问题与原始question 非常相似：将 ggplot 轴标签中的十进制度数更改为度分秒。

我正在执行以下步骤：

library(ggplot2)
library(ggmap)

#get my map
city<- get_map(location = c(lon= -54.847, lat= -22.25),
                maptype = "satellite",zoom = 11,color="bw")

map<-ggmap(city,extent="normal")+
  xlab("Longitude")+ ylab("Latitude")
map

另外，我正在尝试@Jaap 写的：

scale_x_longitude <- function(xmin=-180, xmax=180, step=1, ...) {
  xbreaks <- seq(xmin,xmax,step)
  xlabels <- unlist(lapply(xbreaks, function(x) ifelse(x < 0, parse(text=paste0(x,"^o", "*W")), ifelse(x > 0, parse(text=paste0(x,"^o", "*E")),x))))
  return(scale_x_continuous("Longitude", breaks = xbreaks, labels = xlabels, expand = c(0, 0), ...))
}
scale_y_latitude <- function(ymin=-90, ymax=90, step=0.5, ...) {
  ybreaks <- seq(ymin,ymax,step)
  ylabels <- unlist(lapply(ybreaks, function(x) ifelse(x < 0, parse(text=paste0(x,"^o", "*S")), ifelse(x > 0, parse(text=paste0(x,"^o", "*N")),x))))
  return(scale_y_continuous("Latitude", breaks = ybreaks, labels = ylabels, expand = c(0, 0), ...))
} 

所以：

map+
  scale_x_longitude(-55.0,-54.7,4)+
  scale_y_latitude(-22.4,-22.1,4)

在第二张地图中，仅绘制了两个坐标并且格式错误。 我需要将这些坐标写成如下：

55ºW, 54ºW 54',54ºW 48', 54ºW 42'; 22ºS 24', 22ºS 18', 22ºS 12', 22ºS 06'

谁能帮帮我？

更新 (16/08/2017) 这是@Rafael Cunha 提供的更新代码（非常感谢！） 仍然缺少添加分钟符号的方法。但是，它比以前工作得更好。

scale_x_longitude <- function(xmin=-180, xmax=180, step=1, ...) {
  xbreaks <- seq(xmin,xmax,step)
  xlabels <- unlist(
    lapply(xbreaks, function(x){
      ifelse(x < 0, parse(text=paste0(paste0(abs(dms(x)$d),"^{o}*"),
                                      paste0(abs(dms(x)$m)), "*W")), 
             ifelse(x > 0, parse(text=paste0(paste0(abs(dms(x)$d),"^{o}*"),
                                             paste0(abs(dms(x)$m)),"*E")),
                    abs(dms(x))))}))
  return(scale_x_continuous("Longitude", breaks = xbreaks, labels = xlabels, expand = c(0, 0), ...))
}

scale_y_latitude <- function(ymin=-90, ymax=90, step=0.5, ...) {
  ybreaks <- seq(ymin,ymax,step)
  ylabels <- unlist(
    lapply(ybreaks, function(x){
      ifelse(x < 0, parse(text=paste0(paste0(abs(dms(x)$d),"^{o}*"),
                                      paste0(abs(dms(x)$m)),"*S"), 
             ifelse(x > 0, parse(text=paste0(paste0(abs(dms(x)$d),"^{o}*"),
                                             paste0(abs(dms(x)$m)),"*N")),
                    abs(dms(x))))}))
  return(scale_y_continuous("Latitude", breaks = ybreaks, labels = ylabels, expand = c(0, 0), ...))
}  

map+
  scale_x_longitude(-55.0,-54.7,.1)+
  scale_y_latitude(-22.4,-22.1,.1)

Answer 1

@蒂亚戈席尔瓦泰勒斯，

基于@Rafael Cunha 提供的代码（谢谢，我也会使用它），表达式函数（无论如何对我来说）可以在绘图轴上提供度数、分钟和秒标签。

将 DD 转换为 DMS 以进行 ggmap 轴绘图的函数。

scale_x_longitude <- function(xmin=-180, xmax=180, step=0.002, ...) {
  xbreaks <- seq(xmin,xmax,step)
  xlabels <- unlist(
    lapply(xbreaks, function(x){
      ifelse(x < 0, parse(text=paste0(paste0(abs(dms(x)$d), expression("*{degree}*")),
                                      paste0(abs(dms(x)$m), expression("*{minute}*")),
                                      paste0(abs(dms(x)$s)), expression("*{second}*W"))), 
             ifelse(x > 0, parse(text=paste0(paste0(abs(dms(x)$d), expression("*{degree}*")),
                                             paste0(abs(dms(x)$m), expression("*{minute}*")),
                                             paste0(abs(dms(x)$s)), expression("*{second}*E"))),
                    abs(dms(x))))}))
  return(scale_x_continuous("Longitude", breaks = xbreaks, labels = xlabels, expand = c(0, 0), ...))
}

scale_y_latitude <- function(ymin=-90, ymax=90, step=0.002, ...) {
  ybreaks <- seq(ymin,ymax,step)
  ylabels <- unlist(
    lapply(ybreaks, function(x){
      ifelse(x < 0, parse(text=paste0(paste0(abs(dms(x)$d), expression("*{degree}*")),
                                      paste0(abs(dms(x)$m), expression("*{minute}*")),
                                      paste0(abs(dms(x)$s)), expression("*{second}*S"))), 
             ifelse(x > 0, parse(text=paste0(paste0(abs(dms(x)$d), expression("*{degree}*")),
                                             paste0(abs(dms(x)$m), expression("*{minute}*")),
                                             paste0(abs(dms(x)$s)), expression("*{second}*N"))),
                    abs(dms(x))))}))
  return(scale_y_continuous("Latitude", breaks = ybreaks, labels = ylabels, expand = c(0, 0), ...))
}  

Stackexchange 的示例地图

library(ggplot2)
library(ggmap)
map <- get_map(location = "Alabama",
               zoom = 8,
               maptype = "toner", source = "stamen",
               color = "bw")
sam_map <- ggmap(map) +
  theme_minimal() + theme(legend.position = "none")

sam_map +
  scale_x_longitude(-89, -85, 0.75) +
  scale_y_latitude(30, 34, 0.75)

我不得不修改“步骤”（在函数代码和调用中）以使其正确显示并以所需的时间间隔显示。这仍然可以改进以在更大的范围内省略几秒钟或几分钟。我确实喜欢它以非常小的比例提供小数秒。程序员/编码员不多，但这似乎确实有效。

Map of LA (Lower Alabama) with DMS (proper formatting)

Answer 2

我使用 GEOmap 包中的函数 dms 将十进制度转换为度分秒。我的代码中唯一缺少的是将分钟粘贴到轴标签中的方法。

图书馆（ggplot2） 图书馆（ggmap） 图书馆（地理地图）

#get my map
city<- get_map(location = c(lon= -54.847, lat= -22.25),
               maptype = "satellite",zoom = 11,color="bw")

map<-ggmap(city,extent="normal")+
  xlab("Longitude")+ ylab("Latitude")

scale_x_longitude <- function(xmin=-180, xmax=180, step=1, ...) {
  xbreaks <- seq(xmin,xmax,step)
  xlabels <- unlist(lapply(xbreaks, function(x) ifelse(x < 0, parse(text=paste0(abs(dms(x)$d),"^o", "*W")), ifelse(x > 0, parse(text=paste0(abs(dms(x)$d),"^o", "*E")),abs(dms(x))))))
  return(scale_x_continuous("Longitude", breaks = xbreaks, labels = xlabels, expand = c(0, 0), ...))
}
scale_y_latitude <- function(ymin=-90, ymax=90, step=0.5, ...) {
  ybreaks <- seq(ymin,ymax,step)
  ylabels <- unlist(lapply(ybreaks, function(x) ifelse(x < 0, parse(text=paste0(abs(dms(x)$d),"^o", "*S")), ifelse(x > 0, parse(text=paste0(abs(dms(x)$d),"^o", "*N")),abs(dms(x))))))
  return(scale_y_continuous("Latitude", breaks = ybreaks, labels = ylabels, expand = c(0, 0), ...))
} 

map+
  scale_x_longitude(-55.0,-54.7,.1)+
  scale_y_latitude(-22.4,-22.1,.1)