R：ggplot 在日期时间未显示 geom_segment

Question

我想在日期时间上绘制一个 geom_segment，就像一个简单的甘特图。我从数据框 (df) 中绘制了一个 geom_segment，然后在 ggplot 中绘制了一个 geom_segment。问题是，当 x 尺度限制与 geom_segment 重叠时，它就会消失。但只有 geom_segment 从数据框创建。另一个工作正常。这是代码：

    output$TA_2 <- renderPlot({

    df <- data.frame("Start" = c("2019-08-13"),
                   "End" = c("2019-08-15"),
                   "y" = c(1))

    df$Start <- as.POSIXct(2019-01-01, origin = df$Start)
    df$End <- as.POSIXct(2019-01-01, origin = df$End)

    ggplot(df, aes(x = Start, y = y)) +
      geom_segment(aes(xend = End, yend = y), size=4) +
      theme_bw() +
      scale_y_continuous(limits=c(0,3)) +
      scale_x_datetime(date_breaks = "24 hour", labels = date_format("%d.%m - %H:%M"), 
                     minor_breaks = "24 hour", expand=c(0,0),
                     limits = c(
                       as.POSIXct(2019-01-01, origin = "2019-08-14"),
                       as.POSIXct(2019-01-01, origin = "2019-08-16")
                     )) +
      geom_segment(x = as.POSIXct(2019-01-01, origin = "2019-08-13"), 
                 xend = as.POSIXct(2019-01-01, origin = "2019-08-15"), 
                 y = 2, yend = 2, size=1)
})

如果x-scale限制

limits = c(
as.POSIXct(2019-01-01, origin = "2019-08-14"),
...

调整为例如

limits = c(
as.POSIXct(2019-01-01, origin = "2019-08-10"),
...

两个片段都出现了。

我必须做什么，从数据框创建的段也可以重叠工作？

Answer 1

您可以使用 coord_cartesian，而不是在 scale_x_datetime 中设置限制来切断您的 df，它只会放大并保留片段。

ggplot(df, aes(x = Start, y = y)) +
  geom_segment(aes(xend = End, yend = y), size=4) +
  theme_bw() +
  scale_y_continuous(limits=c(0,3)) +
  scale_x_datetime(date_breaks = "24 hour", labels = date_format("%d.%m - %H:%M"), 
                   minor_breaks = "24 hour", expand=c(0,0)) +
  geom_segment(x = as.POSIXct(2019-01-01, origin = "2019-08-13"), 
               xend = as.POSIXct(2019-01-01, origin = "2019-08-15"), 
               y = 2, yend = 2, size=1) +
  coord_cartesian(xlim = c(
    as.POSIXct(2019-01-01, origin = "2019-08-14"),
    as.POSIXct(2019-01-01, origin = "2019-08-16")
  ))

R：ggplot 在日期时间未显示 geom_segment

R: ggplot not showing geom_segment over datetime

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