geom_point与geom_errorbarh的position dodge调整问题：数据点与误差棒间距过大

绘图脚本 #

dat_combined %>% arrange(depth_cm) %>% ggplot(aes(x = mean_delta_13C, y = depth_cm)) + 
  geom_errorbarh(aes(xmin = mean_delta_13C - sd_delta_13c, xmax = mean_delta_13C + sd_delta_13c, color = site), height = 0.2, size = 0.5, position = position_dodge2(width = 0.3)) + 
  geom_path(aes(group = interaction(Type, site)))+ 
  geom_point(aes(color = site, shape = Type), size = 2.5, position = position_dodge2(width = 0.1)) + 
  scale_color_manual(values = site_colors, labels = new_names) + 
  labs(x = expression(delta^13*"C (‰)"), y = "Soil depth (cm)", color = "Ecosystem", shape = element_blank())+ 
  scale_x_reverse(position = "top") + 
  scale_y_discrete(limits = rev(depths)) + 
  theme_pubr() 

问题描述 #

生成的图表中，数据点与对应误差棒的横向间距过大（问题区域已用绿色圈出）。

解决方案 #

问题根源是geom_errorbarh和geom_point的position_dodge2(width)参数值不一致：误差棒用了width=0.3，而点用了width=0.1，导致两者错位。只需将两个图层的该参数设为相同值，即可让点与误差棒对齐。

修改后的核心代码示例：

geom_errorbarh(..., position = position_dodge2(width = 0.3)) + 
geom_point(..., position = position_dodge2(width = 0.3))

若希望布局更紧凑，可适当减小width数值（比如设为0.2），但必须保证两个图层的参数完全一致。

内容的提问来源于stack exchange，提问作者J.M