ggplot设置坐标轴范围：如何将Y轴固定为1-5？

你设置Y轴范围没生效的核心原因是用了coord_flip()翻转了坐标轴——原来的Y轴（对应mean数值）被转换成了翻转后的X轴，之前针对Y轴的配置自然作用不到目标轴上。

给你两种可行的解决办法：

方法一：直接针对翻转后的轴设置范围 #

既然翻转后mean对应X轴，那就把coord_cartesian的参数改成xlim：

n <- 10000

test <- data.frame(value = sample(1:5, size = n, replace = TRUE),
                   grp = sample(c("A", "B", "C"), size = n, replace = TRUE),
                   item = sample(c("Item1", "Item2", "Item3", "Item4", "Item5", "Item6"), size = n, replace = TRUE)) 
                   
test %>%
  group_by(item, grp) %>%
  summarise(mean = mean(value, na.rm=TRUE)) %>%
  ungroup() %>%
  
  ggplot(aes(x = item, y = mean, group = grp, fill = grp)) +
    geom_col(position = 'dodge') +
    coord_cartesian(xlim=c(1, 5)) + # 修改为xlim
    coord_flip() 

方法二：先设置原Y轴的范围和刻度，再翻转 #

用scale_y_continuous同时指定范围和刻度，之后再翻转坐标轴，ggplot会自动将配置映射到翻转后的对应轴：

n <- 10000

test <- data.frame(value = sample(1:5, size = n, replace = TRUE),
                   grp = sample(c("A", "B", "C"), size = n, replace = TRUE),
                   item = sample(c("Item1", "Item2", "Item3", "Item4", "Item5", "Item6"), size = n, replace = TRUE)) 
                   
test %>%
  group_by(item, grp) %>%
  summarise(mean = mean(value, na.rm=TRUE)) %>%
  ungroup() %>%
  
  ggplot(aes(x = item, y = mean, group = grp, fill = grp)) +
    geom_col(position = 'dodge') +
    scale_y_continuous(limits = c(1,5), breaks = seq(1,5,1)) + # 先设置原Y轴
    coord_flip() 

两种方法都能帮你把目标轴的刻度范围固定在1到5之间。

内容的提问来源于stack exchange，提问作者D. Studer