你看过scales包了吗？你可以用breaks_pretty指定你想要的x轴刻度线和标签的数量，并用label_date指定日期格式，而不是手动创建x轴刻度线和标签。

library(tidyverse)
library(scales)
time <- seq(as.Date("2020-1-1"), as.Date("2022-1-1"), by = "months")
var <- c(1:15, 15:6)
df <- data.frame(var, time) %>%
  mutate(time = as.Date(time))

# original
df %>%
  ggplot(aes(x = time, y = var)) +
  geom_bar(stat = "identity")

# just month names
df %>%
  ggplot(aes(x = time, y = var)) +
  geom_bar(stat = "identity") + 
  scale_x_date(labels = label_date("%B"))

# increase tick marks with month names and full year
df %>%
  ggplot(aes(x = time, y = var)) +
  geom_bar(stat = "identity") + 
  scale_x_date(labels = label_date("%B %Y"),
               breaks = breaks_pretty(n = 12)) # <- change 12 to another number