如何修正ggpattern柱状图仅部分柱子加图案时的图例错误

使用ggpattern绘制柱状图时，指定仅为部分柱子添加图案（通过scale_pattern_manual），图表中的图案显示符合预期，但图例中所有柱子变量都显示条纹图案，如何修正？

解决方案 #

核心问题是图例的图案映射未与scale_pattern_manual的设置同步，通过调整刻度设置和自定义图例符号即可解决，修改后的完整代码如下：

library(data.table)
library(ggpattern)
library(ggplot2)

mwe <- structure(list(time = c(2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024,
                               2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024,
                               2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024, 
                               2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024,
                               2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024),
                      variable = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
                                             2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 
                                             3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
                                             4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L,
                                             5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L),
                                           levels = c("line", "colA", "colB", "colC", "colD"),
                                           class = "factor"),
                      value = c(0.357009288818499, 
                                1.71988206941869, 0.718233226499176, 0.731459804415735, 1.32156929908822, 
                                0.560209948397006, 0.458172276280688, -0.545085303407777, 0.341824064319862, 
                                0.548992565644735, 1.67689305057888, 0.731572600674735, 0.565083479982942, 
                                -1.50947739133498, 2.07670813142427, 1.05184988035862, -0.649722543167019, 
                                NA, -0.454897957364349, -0.560726446108042, -0.505986125219531, 
                                -0.436527260421888, 0.472106640040311, -0.55586138196329, -0.764628982718829, 
                                -0.402292611965036, -0.276831035898875, -0.0919962180055433, 
                                0.198944308210276, 0.0475753047954131, 0.0408311042257559, 1.99036972882494, 
                                -1.3873165419347, -0.267642645661357, 0.0537581061845893, 0.0396657211136064, 
                                0.354910898543741, 0.404771156737533, 0.445071446248599, 0.562072480628934, 
                                0.368570321557913, 0.426679740870766, 0.438594024302237, 0.453171745539747, 
                                NA)),
                 row.names = c(NA, -45L),
                 class = c("data.table", "data.frame"))

p <-
  ggplot(mapping = aes(y = value,
                       x = time
                       )
         ) +
  geom_col_pattern(data = mwe[variable != "line"],
                   aes(fill = variable,
                       pattern = variable
                       ),
                   width = .8
                   ) +
  geom_line(data = mwe[variable == "line"],
            aes(color = variable),
            linewidth = 1
            ) +
  geom_hline(yintercept = 0) +
  theme(axis.text.x = element_text(angle = 45, hjust=1)) +
  labs(x = NULL,
       y = "(%)") +
  scale_x_continuous(breaks = seq(min(mwe$time), max(mwe$time), by=2)) +
  scale_fill_manual(limits = c("colA", "colB", "colC", "colD", "line"),
                    values = c("#005390", "#E75118", "#2F8CFF", "#FFC81D", "black"),
                    labels = c("A", "B", "C", "D", "Line"),
                    aesthetics = c("fill", "color")
                    ) +
  # 同步刻度范围与fill一致，给无图案变量设NA并指定na.value
  scale_pattern_manual(limits = c("colA", "colB", "colC", "colD", "line"),
                       values = c(NA, NA, "stripe", "crosshatch", NA),
                       labels = c("A", "B", "C", "D", "Line"),
                       na.value = "none"
                       ) +
  # 自定义图例符号，区分线条和柱状图
  guides(fill = guide_legend(nrow = 2, byrow = TRUE,
                             key_glyph = function(data, params, size) {
                               if (data$variable == "line") {
                                 draw_key_path(data, params, size)
                               } else {
                                 draw_key_col_pattern(data, params, size)
                               }
                             }),
         pattern = "none")
print(p)

关键修改说明 #

1. 统一刻度映射范围：
   • 将scale_pattern_manual的limits扩展为包含所有变量，确保和scale_fill_manual的刻度范围完全匹配
   • 给不需要图案的变量（colA、colB、line）设置values = NA，并通过na.value = "none"指定无图案的显示规则
2. 自定义图例符号：
   • 在guide_legend中添加key_glyph函数，分别为线条和柱状图指定对应的图例绘制函数，保证图例显示与实际图形一致

修改后，图例中的每个项会正确显示对应的图案（或无图案），和图表中的柱子显示保持同步。

内容的提问来源于stack exchange，提问作者gitcanzo