为什么 ggplot geom_col 极限处的条形不可见，但标签可见？

Question

I am trying to set the limits of a geom_col() plot to include only specific dates. However, when I attempt to set the limit with scale_x_date() the bars for the end points disappear. If the end points are moved, the new end points disappear.

library(ggplot2)
TestData <- data.frame(
  "Date" = as.Date(c('2020-10-16','2020-10-17','2020-10-18', '2020-10-19', '2020-10-20')),
  "Number" = c(5,3,2,4,1)
)


ggplot(TestData, aes(x = Date, y = Number, fill = 'red', col = 'white')) + 
  geom_col() + 
  scale_x_date(limits = as.Date(c('2020-10-17','2020-10-19'))) + 
  geom_text(aes(label=Number), vjust = -0.5) +
  ylim(0,15)

The above MWE generates the plot below.

The same issue occurs regardless of whether I use xlim() or scale_x_date() .

Answer 1

I agree the best way to deal with this is to filter your data. You can do this with dplyr

library(dplyr)
TestData %>% 
  filter(Date>='2020-10-17' & Date<='2020-10-19') %>% 
  ggplot(aes(x = Date, y = Number, fill = 'red', col = 'white')) + 
  geom_col() + 
  geom_text(aes(label=Number), vjust = -0.5) +
  ylim(0,15)

You could also technically do it with a scale but it's kind of a hack. You just need to adjust the end points a bit to filter out the other geoms to make sure they get dropped.

ggplot(TestData, aes(x = Date, y = Number, fill = 'red', col = 'white')) + 
  geom_col() + 
  scale_x_date(limits=as.Date(c('2020-10-17','2020-10-19')) + c(-.5, .5)) +
  geom_text(aes(label=Number), vjust = -0.5) +
  ylim(0,15)

This still generates a warning message about the dropped values.