PROSAGA码农传奇-模型可视化-ggplot - 面板边框交替黑色和白色矩形

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    这很冗长，但这里是如何制作边框网格。您可以重复使用此代码，而不会在不同的地图之间进行重大更改，仅更新您为纬度和经度的最小值，最大值和间隔定义的值。
  
   <pre>
 <code>
 require(ggplot2)
require(maps)

world <- map_data("world2") #get map data

</code>
 </pre>
  
    首先，定义纬度和经度的最小值，最大值和网格间隔。这些数字将用于为边框网格矩形创建数据框，并在绘图中创建轴断点和限制。
  
   <pre>
 <code>
 min.lat <- -40
max.lat <- 40
interval.lat <- 20
min.long <- 0
max.long <- 90
interval.long <- 30

</code>
 </pre>
  
    接下来，创建一个包含矩形坐标的数据框，这些矩形将形成黑/白边框网格。此代码全部编写为使用上面定义的值而不是实际数字，因此您无需更改下面的代码来创建不同区域的地图，您只需要更新上面定义的值。
  
   <pre>
 <code>
 #define a constant (scaled to map size) width for grid rectangles
#may need to adjust number to get width you prefer
grid.width <- (max.lat - min.lat)/90

is.even <- function(x) x %% 2 == 0 #function to test if number is even

#dataframe of longitude rectangles
rects.long <- data.frame(x_start = rep(seq(min.long, max.long - interval.long,
 by = interval.long), 2))
rects.long$x_end <- rects.long$x_start + interval.long
rects.long$y_start <- c(rep(min.lat, nrow(rects.long)/2),
 rep(max.lat - grid.width, nrow(rects.long)/2))
rects.long$y_end <- c(rep(min.lat + grid.width, nrow(rects.long)/2),
 rep(max.lat, nrow(rects.long)/2))

rects.long$color <- if(is.even(nrow(rects.long)/2)) { #even/odd test
 rep(c("black", "white"), nrow(rects.long)/2) #pattern for even
} else {
 rep(c(rep(c("black", "white"), (nrow(rects.long) - 2)/4),"black"), 2)} #odd

#dataframe of latitude rectangles
rects.lat <- data.frame(y_start = rep(seq(min.lat, max.lat - interval.lat,
 by = interval.lat), 2))
rects.lat$y_end <- rects.lat$y_start + interval.lat
rects.lat$x_start <- c(rep(min.long, nrow(rects.lat)/2),
 rep(max.long - grid.width, nrow(rects.lat)/2))
rects.lat$x_end <- c(rep(min.long + grid.width, nrow(rects.lat)/2),
 rep(max.long, nrow(rects.lat)/2))

rects.lat$color <- if(is.even(nrow(rects.lat)/2)) { #even/odd test
 rep(c("black", "white"), nrow(rects.lat)/2) #pattern for even
} else {
 rep(c(rep(c("black", "white"), (nrow(rects.lat) - 2)/4),"black"), 2)} #odd

#combine latitude and longitude grid
rects.grid <- rbind(rects.lat, rects.long)

</code>
 </pre>
  
    最后，制作你的情节！
  
   <pre>
 <code>
 #define axis breaks to match grid
axis.breaks.x <- seq(min.long, max.long, interval.long)
axis.breaks.y <- seq(min.lat, max.lat, interval.lat)

ggplot(data = world) +
  geom_polygon(aes(x = long, y = lat, group = group),
               color = "black", fill = "gray50") +
  #set limits to your previously defined limits
  coord_fixed(1, xlim = c(min.long, max.long), ylim = c(min.lat, max.lat),
              expand = FALSE) +
  #define breaks same as grid, duplicate axes for lat/long labels on all sides
  scale_y_continuous(breaks = axis.breaks.y, sec.axis = dup_axis()) +
  scale_x_continuous(breaks = axis.breaks.x, sec.axis = dup_axis()) +
  #use geom_rect() to add border grid
  geom_rect(data = rects.grid, inherit.aes = FALSE,
            aes(xmin = x_start, xmax = x_end, ymin = y_start, ymax = y_end,
                fill = color), color = "black") +
  scale_fill_manual(values = c("black", "white")) +
  theme_minimal() + #theme edits to make plot look like a map
  theme(axis.title = element_blank(),
        legend.position = "none")

</code>
 </pre>
  
    <a href="https://i.stack.imgur.com/cRe7W.jpg" rel="noreferrer">
      <img src =“https://i.stack.imgur.com/cRe7W.jpg”alt =“在此处输入图片说明”/>
    </A>
  
  
    这是一个测试，以检查此代码是否适用于不同的限制和间隔：
  
   <pre>
 <code>
 min.lat <- -10
max.lat <- 50
interval.lat <- 10
min.long <- 60
max.long <- 150
interval.long <- 15
#run same code as above to create grid dataframes and plot

</code>
 </pre>
  
    <a href="https://i.stack.imgur.com/tfYxH.jpg" rel="noreferrer">
      <img src =“https://i.stack.imgur.com/tfYxH.jpg”alt =“在此输入图像说明”/>
    </A>
  
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