多因子ggplot图表：如何在图例中正确实现图案样式？

我已经完成了Practice和Focus两个参数的图例配置，但Sequence对应的第三个图例元素（标注为"practice"）未按预期显示——我需要它呈现黑色填充的条纹图案。

示例数据集 #

df <- data.frame(Practice = factor(rep(c('A','B'), 216)),
                 Focus = factor(rep(c("high","high","low","low"), each = 216)), 
                 Session = factor(rep(c(1:6), each=72)),
                 Sequence = factor(rep(c('X','X','X','Y','Y','Y','Z','Z','Z'), 48)),
                 Hand = factor(rep(c('L','R','R','L'), 108)),
                 value = sample(0:100, 432, rep = TRUE)) %>%
  unite('group', c(Practice,Focus,Hand), remove=FALSE)

原绘图代码 #

ggplot(df, aes(x=Session, y=value, fill= Focus, pattern = Sequence)) +
  theme_classic() +
  facet_wrap(vars(group), nrow=4)  +
  geom_boxplot_pattern(outlier.shape=NA, position='dodge', key_glyph = 'rect',
    aes(alpha = Practice, fill = Focus,
      pattern_density = Sequence, pattern_angle = Sequence), 
    pattern = 'stripe', pattern_fill = 'white', pattern_colour = 'white', pattern_spacing = 0.02) +
  geom_point(size=0.25, position=position_jitterdodge(0.2), show.legend = FALSE)    +
  scale_alpha_discrete(range = c(1,0.3)) +
  scale_fill_brewer(palette = "Set1") +
  scale_pattern_density_manual(values = c(0,0.05,0.05), labels=c('different','mirror','practice')) + 
  scale_pattern_angle_manual(values = c(0,315,45), guide = "none") + 
  guides(alpha   = guide_legend(order=1, override.aes = list(fill='grey30', pattern='none')) ) + 
  guides(fill    = guide_legend(order=2, override.aes = list(pattern='none')) ) +
  guides(pattern_density = guide_legend(order=3, override.aes = list(
    fill='black',pattern = 'stripe', pattern_fill = 'white', pattern_colour = 'white', pattern_spacing = 0.02, pattern_density=0.05, pattern_angle=45) )) + 
  #guides(pattern_angle   = guide_legend(order=4, override.aes = list(fill='black', pattern_size=0.1)) ) +
  scale_y_continuous(breaks = seq(0,1500,200)) + ylab('Reaction time in ms') + geom_vline(xintercept=5.5,  color = "grey", linetype="dotted" ) #+

解决方案 #

问题出在pattern_density图例的override.aes设置上——之前统一给所有图例条目设置了黑色填充，但实际上只需要给第三个条目（对应"practice"）设置黑色，同时要确保每个条目的图案属性匹配对应Sequence水平的设置。

修改后的代码：

ggplot(df, aes(x=Session, y=value, fill= Focus, pattern = Sequence)) +
  theme_classic() +
  facet_wrap(vars(group), nrow=4)  +
  geom_boxplot_pattern(outlier.shape=NA, position='dodge', key_glyph = 'rect',
    aes(alpha = Practice, fill = Focus,
      pattern_density = Sequence, pattern_angle = Sequence), 
    pattern = 'stripe', pattern_fill = 'white', pattern_colour = 'white', pattern_spacing = 0.02) +
  geom_point(size=0.25, position=position_jitterdodge(0.2), show.legend = FALSE)    +
  scale_alpha_discrete(range = c(1,0.3)) +
  scale_fill_brewer(palette = "Set1") +
  scale_pattern_density_manual(values = c(0,0.05,0.05), labels=c('different','mirror','practice')) + 
  scale_pattern_angle_manual(values = c(0,315,45), guide = "none") + 
  guides(alpha   = guide_legend(order=1, override.aes = list(fill='grey30', pattern='none')) ) + 
  guides(fill    = guide_legend(order=2, override.aes = list(pattern='none')) ) +
  # 为每个图例条目单独指定样式
  guides(pattern_density = guide_legend(
    order=3, 
    override.aes = list(
      fill = c(scale_fill_brewer(palette = "Set1")$palette(2)[1], 
               scale_fill_brewer(palette = "Set1")$palette(2)[1], 
               "black"), # 前两个沿用Focus的填充色，第三个设为黑色
      pattern = c("none", "stripe", "stripe"),
      pattern_fill = c(NA, "white", "white"),
      pattern_colour = c(NA, "white", "white"),
      pattern_density = c(0, 0.05, 0.05),
      pattern_angle = c(0, 315, 45)
    )
  )) + 
  scale_y_continuous(breaks = seq(0,100,20)) + # 匹配示例数据的value范围
  ylab('Reaction time in ms') + 
  geom_vline(xintercept=5.5,  color = "grey", linetype="dotted" )

关键修改说明 #

• 在pattern_density的override.aes中，为三个图例条目分别指定样式：
  • 前两个条目（different、mirror）沿用scale_fill_brewer的默认填充色，保持和图表主体元素一致；
  • 第三个条目（practice）设置fill='black'，同时匹配对应的条纹参数（密度、角度等）；
• 调整y轴刻度，使其匹配示例数据的value范围（0-100），避免原代码中刻度范围过大的问题。

内容的提问来源于stack exchange，提问作者SDahm