如何移除ggplot2图例中符号周围的方框

问题 #

无法移除ggplot2图例中符号周围的方框，以下是代码、数据片段及生成的图表：

代码 #

theme_opts_V5 <- list(theme(
  panel.grid.minor.x = element_line(color = "transparent"),
  panel.grid.major.x = element_line(color = "transparent"),
  panel.grid.minor = element_line(color = "grey"),
  panel.grid.major = element_line(color = "grey"),
  panel.background = element_blank(),
  plot.background = element_rect(),
  panel.border = element_blank(),
  axis.line = element_line(colour = "black")
))

ggplot(data, aes(x = value, y = old_value, fill = category, color = category)) +
  geom_hline(
    yintercept = 0, linetype = "solid",
    color = "#898800", size = 1
  ) +
  geom_vline(
    xintercept = 57, linetype = "solid",
    color = "#898800", size = 1
  ) +
  geom_text(aes(x = 61, label = "Mean", y = 15), colour = "#898800", angle = 0, size = 3.4) +
  geom_point(size = 3, shape = 23) +
  labs(
    title = "Title",
    subtitle = "Subtitle",
    caption = "Source"
  ) +
  xlab("new, in %") +
  ylab("change to old") +
  scale_color_manual(values = c("#440154", "#3b528b")) +
  scale_fill_manual(values = c("#440154", "#3b528b")) +
  theme(
    legend.title = element_blank(),
    legend.position = "bottom",
    legend.key = element_rect(fill = NA)
  ) +
  theme(legend.background = element_blank()) +
  theme_opts_V5 +
  scale_x_continuous(limits = c(30, 80), breaks = seq(30, 80, by = 10), expand = c(0, 0)) +
  scale_y_continuous(limits = c(-30, 20), breaks = seq(-30, 20, by = 10), expand = c(0, 0))

数据片段 #

structure(list(city = c("Aadorf", "Affeltrangen", "Altnau", "Amlikon-Bissegg", 
"Amriswil", "Arbon", "Basadingen-Schlattingen", "Berg", "Berlingen", 
"Bettwiesen", "Bichelsee-Balterswil", "Birwinken", "Bischofszell", 
"Bottighofen", "Braunau", "Bürglen", "Bussnang", "Diessenhofen", 
"Dozwil", "Egnach"), value = c(55L, 48L, 60L, 70L, 63L, 76L, 
52L, 42L, 53L, 49L, 49L, 57L, 70L, 36L, 49L, 69L, 47L, 47L, 44L, 
57L), old_value = c(4L, 2L, -1L, 0L, 0L, 0L, 3L, -3L, -2L, 6L, 
5L, -11L, -2L, -3L, -3L, 6L, -3L, 0L, -8L, -3L), category = c("low", 
"low", "low", "low", "high", "high", "low", "low", "low", "low", 
"low", "low", "low", "low", "low", "low", "low", "low", "low", 
"low")), row.names = c(NA, 20L), class = "data.frame")

生成图表 #

补充说明 #

theme_opts_V5仅定义绘图的背景和网格线：

theme_opts_V5 <- list(theme(panel.grid.minor.x = element_line(color = "transparent"),
                            panel.grid.major.x = element_line(color = "transparent"),
                            panel.grid.minor = element_line(color = "grey"),
                            panel.grid.major = element_line(color = "grey"),
                            panel.background = element_blank(),
                            plot.background = element_rect(),
                            panel.border = element_blank(),
                            axis.line = element_line(colour = "black")))

解决方案 #

问题出在主题设置的加载顺序：你先设置了legend.key = element_rect(fill = NA)，但后面加载的theme_opts_V5没有指定legend.key的边框颜色，导致默认黑色边框被保留。要彻底移除方框，需要同时设置legend.key的fill和colour为NA，并确保该设置不被后续主题覆盖。

有两种修改方式：

方式一：调整theme设置顺序 #

把自定义图例的theme代码移到theme_opts_V5之后，避免被覆盖：

ggplot(data, aes(x = value, y = old_value, fill = category, color = category)) +
  geom_hline(
    yintercept = 0, linetype = "solid",
    color = "#898800", size = 1
  ) +
  geom_vline(
    xintercept = 57, linetype = "solid",
    color = "#898800", size = 1
  ) +
  geom_text(aes(x = 61, label = "Mean", y = 15), colour = "#898800", angle = 0, size = 3.4) +
  geom_point(size = 3, shape = 23) +
  labs(
    title = "Title",
    subtitle = "Subtitle",
    caption = "Source"
  ) +
  xlab("new, in %") +
  ylab("change to old") +
  scale_color_manual(values = c("#440154", "#3b528b")) +
  scale_fill_manual(values = c("#440154", "#3b528b")) +
  theme_opts_V5 +  # 先加载通用主题
  theme(
    legend.title = element_blank(),
    legend.position = "bottom",
    legend.key = element_rect(fill = NA, colour = NA),  # 同时设置填充和边框为透明
    legend.background = element_blank()
  ) +
  scale_x_continuous(limits = c(30, 80), breaks = seq(30, 80, by = 10), expand = c(0, 0)) +
  scale_y_continuous(limits = c(-30, 20), breaks = seq(-30, 20, by = 10), expand = c(0, 0))

方式二：整合图例设置到通用主题 #

直接修改theme_opts_V5，加入图例相关设置，减少重复代码：

theme_opts_V5 <- list(theme(
  panel.grid.minor.x = element_line(color = "transparent"),
  panel.grid.major.x = element_line(color = "transparent"),
  panel.grid.minor = element_line(color = "grey"),
  panel.grid.major = element_line(color = "grey"),
  panel.background = element_blank(),
  plot.background = element_rect(),
  panel.border = element_blank(),
  axis.line = element_line(colour = "black"),
  # 新增图例设置
  legend.title = element_blank(),
  legend.position = "bottom",
  legend.key = element_rect(fill = NA, colour = NA),
  legend.background = element_blank()
))

ggplot(data, aes(x = value, y = old_value, fill = category, color = category)) +
  geom_hline(
    yintercept = 0, linetype = "solid",
    color = "#898800", size = 1
  ) +
  geom_vline(
    xintercept = 57, linetype = "solid",
    color = "#898800", size = 1
  ) +
  geom_text(aes(x = 61, label = "Mean", y = 15), colour = "#898800", angle = 0, size = 3.4) +
  geom_point(size = 3, shape = 23) +
  labs(
    title = "Title",
    subtitle = "Subtitle",
    caption = "Source"
  ) +
  xlab("new, in %") +
  ylab("change to old") +
  scale_color_manual(values = c("#440154", "#3b528b")) +
  scale_fill_manual(values = c("#440154", "#3b528b")) +
  theme_opts_V5 +
  scale_x_continuous(limits = c(30, 80), breaks = seq(30, 80, by = 10), expand = c(0, 0)) +
  scale_y_continuous(limits = c(-30, 20), breaks = seq(-30, 20, by = 10), expand = c(0, 0))

内容的提问来源于stack exchange，提问作者user11841097