scale_fill_manual中系数颜色与顺序不一致问题求助

你在scale_fill_manual和scale_color_manual中设置的limits仅控制图例的显示顺序，但ggplot分组元素（如点、误差线）的排列顺序是由数据中category列的因子水平顺序决定的，而非scale参数。你的原始数据里category是字符型，ggplot会默认按字母顺序（Black、Female、Hispanic、Male、White）处理，这就是绘图顺序和图例不一致的原因。

解决步骤 #

将category转换为指定顺序的因子，让ggplot按照你需要的顺序排列分组元素：

方法1：预处理数据（推荐） #

在绘图前修改数据，把category设置为有序因子：

dtest <- dtest %>%
  mutate(category = factor(category, levels = c("Black", "Hispanic", "White", "Female", "Male")))

方法2：在ggplot的aes中直接指定 #

如果不想修改原始数据，可以在aes里临时转换因子：

dtest %>% 
  ggplot(aes(x = coef, y = as.factor(model),
             xmin = ci_lower, xmax = ci_upper,
             color = factor(category, levels = c("Black", "Hispanic", "White", "Female", "Male")),
             fill = factor(category, levels = c("Black", "Hispanic", "White", "Female", "Male")))) +
  facet_wrap(~outcome, 
             nrow = 3,
             scales = "free") +
  geom_errorbar(width = 0, 
                size = 1.1, 
                alpha = 0.6, 
                position = position_dodge(width = 0.5)) +
  geom_errorbar(aes(x = -coef, xmin = -ci_lower, xmax = -ci_upper),
            width = 0, 
            size = 1.1, 
            alpha = 0, 
            position = position_dodge(width = 0.5)) +
  geom_point(shape = 22, 
             size = 2.5, 
             color = 'white',
             position = position_dodge(width = 0.5)) +
  geom_vline(xintercept = 0, 
             linetype = "dashed", 
             color = "blue",
             linewidth = .3) +
  scale_y_discrete(labels = outcome_labels) +
  scale_fill_manual(values = c("Black" = "indianred2",
                               "Hispanic" = "tan2",
                               "White" = "lightgoldenrod1",
                               "Female" = "gray10",
                               "Male" = "gray70")) +
  scale_color_manual(values = c("Black" = "indianred2",
                               "Hispanic" = "tan2",
                               "White" = "lightgoldenrod1",
                               "Female" = "gray10",
                               "Male" = "gray70")) +
  theme_bw(base_size = 14) +
  theme(legend.title = element_blank())

说明 #

完成上述修改后，position_dodge会按照你指定的因子水平顺序排列每个model对应的分组元素，绘图中的颜色/系数顺序就会和图例保持一致（从上到下：Black、Hispanic、White、Female、Male）。

内容的提问来源于stack exchange，提问作者a_todd12