ggplot2 geom_bar自定义条形间距：同色系条形相连、色系间留空

要实现同cell_color的条形相连，不同颜色条形间留空隙，核心是打破默认的等间距x轴因子布局，手动控制条形的位置。以下是两种可行方案：

方案1：手动设置连续型x轴位置（保留原x轴标签） #

这种方法直接控制每个条形的x坐标，让同颜色的条形紧密排列，不同颜色的条形间留出明显空隙：

library(ggplot2)
library(dplyr)

df <- data.frame(
  cell_color = c("blue", "blue", "red", "red"),
  cell_type = c("neuron", "sc", "neuron", "sc"),
  value = c(10, 15, 8, 12)
)

# 给每个条形分配x位置：同颜色的间隔极小，不同颜色间隔放大
df <- df %>%
  mutate(x_pos = case_when(
    cell_color == "blue" & cell_type == "neuron" ~ 1,
    cell_color == "blue" & cell_type == "sc" ~ 1.08,
    cell_color == "red" & cell_type == "neuron" ~ 2,
    cell_color == "red" & cell_type == "sc" ~ 2.08
  ))

# 定义x轴显示的标签
x_labels <- c("blue_neuron", "blue_sc", "red_neuron", "red_sc")

ggplot(df, aes(x = x_pos, y = value, fill = cell_color)) +
  geom_bar(stat = "identity", width = 0.07) +  # 条形宽度匹配位置间隔
  scale_x_continuous(breaks = df$x_pos, labels = x_labels) +
  scale_fill_manual(values = c("blue" = "blue", "red" = "red")) +
  labs(x = "Cell Type", y = "Value") +
  theme_minimal()

方案2：按颜色分组，组内展示细胞类型（简化布局） #

如果可以接受x轴按颜色分组，这种方法更简洁，同颜色的条形自动相连，不同颜色组之间天然有空隙：

library(ggplot2)

df <- data.frame(
  cell_color = c("blue", "blue", "red", "red"),
  cell_type = c("neuron", "sc", "neuron", "sc"),
  value = c(10, 15, 8, 12)
)

ggplot(df, aes(x = cell_color, y = value, fill = cell_color, group = cell_type)) +
  geom_bar(stat = "identity", position = position_dodge(width = 1)) +
  scale_fill_manual(values = c("blue" = "blue", "red" = "red")) +
  labs(x = "Cell Color", y = "Value") +
  theme_minimal()

说明 #

• 方案1完全保留你原有的x轴标签样式，通过手动调整x坐标实现间距控制，可根据需求微调x_pos的数值和条形宽度，达到理想的空隙效果。
• 方案2更简洁，适合侧重颜色分组展示的场景，x轴以颜色为类别，组内的细胞类型条形紧密排列。

内容的提问来源于stack exchange，提问作者MM1