ggplot-面板边框交替的黑色和白色矩形 [英] ggplot - panel borders alternating black and white rectangles

问题描述

使用ggplot，有没有办法设置黑白矩形交替的面板边框，像这样:

With ggplot, is there a way to set up panel borders with alternation of black and white rectangles, like this :

推荐答案

这很长，但是这里是制作边框的方法.您可以重用此代码，而不必在不同的地图之间进行重大更改，只需更新您定义的最小，最大以及纬度和经度间隔的值即可.

This is lengthy, but here's how to make a border grid. You can reuse this code without major changes among different maps, updating only the values you define for minimum, maximum, and intervals for latitude and longitude.

require(ggplot2)
require(maps)

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

首先，定义纬度和经度的最小，最大和网格间隔.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界限.

First, define your minimum, maximum, and grid interval for latitude and longitude. These numbers will be used to create a dataframe for border grid rectangles and to create axis breaks and limits in your plot.

min.lat <- -40
max.lat <- 40
interval.lat <- 20
min.long <- 0
max.long <- 90
interval.long <- 30

接下来，创建两个数据框，其中包含将形成网格的矩形的坐标，一个数据框用于黑色矩形，一个数据框用于白色矩形.为每种网格矩形颜色创建了单独的数据框，因此您无需使用scale_fill_manual()进行边界网格填充，因此，如果需要，您将能够对数据使用填充美学.编写此代码都是为了使用上面定义的值，而不是实际数字，因此您无需更改下面的代码即可绘制不同区域的地图，只需更新上面定义的值即可.

Next, create two dataframes containing coordinates for the rectangles that will form your grid, one dataframe for black rectangles and one for white rectangles. Separate dataframes for each color of grid rectangle are created so that you will not need to use scale_fill_manual() for border grid fill, and thus will be able to use the fill aesthetic for your data if desired. This code is all written to use the values defined above, rather than actual numbers, so you do not need to change the code below to make a map of a different area, you'll only need to update the values defined above.

#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)

#split into black dataframe and white dataframe
rects.black <- rects.grid[rects.grid$color == "black",]
rects.white <- rects.grid[rects.grid$color == "white",]

最后，让你的情节！

#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.white, inherit.aes = FALSE, #white grid rectangles
        aes(xmin = x_start, xmax = x_end, ymin = y_start, ymax = y_end), 
            color = "black", fill = "white") +
  geom_rect(data = rects.black, inherit.aes = FALSE, #black grid rectangles
        aes(xmin = x_start, xmax = x_end, ymin = y_start, ymax = y_end),
            color = "black", fill = "black") +
  theme_minimal() + #theme edits to make plot look like a map
  theme(axis.title = element_blank(),
        legend.position = "none")

这是一项测试，以检查此代码在不同的限制和间隔下是否起作用:

Here is a test to check that this code works with different limits and intervals:

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

这篇关于ggplot-面板边框交替的黑色和白色矩形的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！