ggplot2绘制北美地图时纬度轴标签不显示，如何解决？

我在用ggplot2绘制北美地图时，经度轴标签能正常显示，但纬度轴标签不出现，怎么设置才能让它显示出来？

library(ggplot2)
library(ggspatial)
library(dplyr)
library(geodata)
library(sf)
library(tidyr)
library(lubridate)

# 北美国家 shp 文件 ----
can <- gadm(country = 'CAN', level = 0, path=tempdir()) %>%
  st_as_sf()
usa <- gadm(country = 'USA', level = 0, path=tempdir()) %>%
  st_as_sf()
mex <- gadm(country = 'MEX', level = 0, path=tempdir()) %>%
  st_as_sf()

# 北美周边国家 shp 文件 ----
cc <- country_codes()
cca <- cc %>%
  filter(UNREGION1 %in% c('Caribbean','Central America'))
cca <- cca$ISO3
cca <- gadm(country = cca, level = 0, path=tempdir()) %>%
  st_as_sf()
green <- gadm(country = 'GRL', level = 0, path=tempdir()) %>%
  st_as_sf()
rus <- gadm(country = 'RUS', level = 0, path=tempdir()) %>%
  st_as_sf()

# 绘制北美地图 ----
ggplot() +
  geom_sf(data = green, mapping = aes(geometry = geometry), color = "black") +
  geom_sf(data = rus, mapping = aes(geometry = geometry), color = "black") +
  geom_sf(data = can, mapping = aes(geometry = geometry), color = "black") +
  geom_sf(data = usa, mapping = aes(geometry = geometry), color = "black") +
  geom_sf(data = cca, mapping = aes(geometry = geometry), color = "black") +
  geom_sf(data = mex, mapping = aes(geometry = geometry), color = "black") +
  coord_sf(xlim = c(-180, -48), ylim = c(12, 84), expand = F) +
  annotation_scale(location = "bl", width_hint = 0.2, text_cex = 1) +
  annotation_north_arrow(location = "bl",
                         which_north = "true",
                         pad_x = unit(0.15, "in"),
                         pad_y = unit(0.3, "in"),
                         style = north_arrow_fancy_orienteering) +
  theme_bw() +
  theme(plot.margin = grid::unit(c(0,2,0,2), "mm"),
        text = element_text(size = 16),
        axis.text.x = element_text(size = 14, color = "black"),
        axis.text.y = element_text(size = 14, color = "black"),
        panel.grid.major = element_blank(),
        panel.background = element_rect(fill = "lightblue"))

问题原因 #

你设置的plot.margin左侧边距仅为2mm，宽度不足以容纳纬度轴标签，导致标签被挤出绘图区域；另外左下角的指北针也可能和标签产生重叠，进一步影响显示。

解决方案 #

1. 增大左侧边距：修改plot.margin的左侧参数，给纬度标签留出足够空间，比如将grid::unit(c(0,2,0,2), "mm")改为grid::unit(c(0,2,0,10), "mm")
2. 调整指北针位置：可以把指北针移到右上角（location = "tr"），或者调整pad_x/pad_y的值，避免和标签重叠

修改后的完整代码 #

library(ggplot2)
library(ggspatial)
library(dplyr)
library(geodata)
library(sf)
library(tidyr)
library(lubridate)

# 北美国家 shp 文件 ----
can <- gadm(country = 'CAN', level = 0, path=tempdir()) %>%
  st_as_sf()
usa <- gadm(country = 'USA', level = 0, path=tempdir()) %>%
  st_as_sf()
mex <- gadm(country = 'MEX', level = 0, path=tempdir()) %>%
  st_as_sf()

# 北美周边国家 shp 文件 ----
cc <- country_codes()
cca <- cc %>%
  filter(UNREGION1 %in% c('Caribbean','Central America'))
cca <- cca$ISO3
cca <- gadm(country = cca, level = 0, path=tempdir()) %>%
  st_as_sf()
green <- gadm(country = 'GRL', level = 0, path=tempdir()) %>%
  st_as_sf()
rus <- gadm(country = 'RUS', level = 0, path=tempdir()) %>%
  st_as_sf()

# 绘制北美地图 ----
ggplot() +
  geom_sf(data = green, mapping = aes(geometry = geometry), color = "black") +
  geom_sf(data = rus, mapping = aes(geometry = geometry), color = "black") +
  geom_sf(data = can, mapping = aes(geometry = geometry), color = "black") +
  geom_sf(data = usa, mapping = aes(geometry = geometry), color = "black") +
  geom_sf(data = cca, mapping = aes(geometry = geometry), color = "black") +
  geom_sf(data = mex, mapping = aes(geometry = geometry), color = "black") +
  coord_sf(xlim = c(-180, -48), ylim = c(12, 84), expand = F) +
  annotation_scale(location = "bl", width_hint = 0.2, text_cex = 1) +
  # 调整指北针到右上角避免重叠
  annotation_north_arrow(location = "tr",
                         which_north = "true",
                         pad_x = unit(0.15, "in"),
                         pad_y = unit(0.3, "in"),
                         style = north_arrow_fancy_orienteering) +
  theme_bw() +
  theme(plot.margin = grid::unit(c(0,2,0,10), "mm"), # 增大左侧边距
        text = element_text(size = 16),
        axis.text.x = element_text(size = 14, color = "black"),
        axis.text.y = element_text(size = 14, color = "black"),
        panel.grid.major = element_blank(),
        panel.background = element_rect(fill = "lightblue"))

内容的提问来源于stack exchange，提问作者tassones