Question

我是初学者所以如果我的问题太基础，我道歉。我输入第一个ggplot2命令已经过了大约4天。我在发帖之前阅读了How can I apply a gradient fill to a geom_rect object in ggplot2?，但这篇文章似乎专注于制作渐变矩形，我已经这样做了。

目标：我想强调哪些美国总统失业＆gt; 10000（单位并不重要，因为我的重点是能够绘制图表。

presidential <- subset(presidential, start > economics$date[1])
ggplot(economics) +
       geom_rect(
         aes(xmin = start, xmax = end, fill = party),
         ymin = -Inf, ymax = Inf, alpha = 0.2,
         data = presidential
       ) +
       geom_vline(
         aes(xintercept = as.numeric(start)),
         data = presidential,
         colour = "grey50", alpha = 0.5
       ) +
       geom_text(
         aes(x = start, y = 2500, label = name),
         data = presidential,
         size = 3, vjust = 0, hjust = 0, nudge_x = 50, check_overlap = TRUE
       ) +
       geom_line(aes(date, unemploy)) +
       geom_rect(
         aes(xmin = start, xmax = end),
         ymin = 10000, ymax = Inf, alpha = 0.4, fill = "chartreuse",
         data = presidential
       ) +
       geom_text(
         aes(x = as.Date("1993-01-20"), y = 12000, label = "High unemployment"),
         size = 3, vjust = 0, hjust = 0, color = "forestgreen"
       )+
       scale_fill_manual(values = c("blue", "red"))

图表输出为：

正如我们所见，我能够为绿色矩形创建一个标签，显示失业＆gt; 10000.但是，我对这种方法不满意，因为这只是一个快速修复（即我通过调整x，y，nudges等参数使其工作）。如果轴的比例变化怎么办？文本将被扭曲或可能不可见。我有两个问题：

问题1：无论如何我们可以通过编程方式标记绿色矩形，以便失业＆gt; 10000？我不太关心我们是否使用文字，标签或图例。我假设使用geom_text()需要快速修复（即大量运行和重新运行以确保通过不断调整x，y，vjust，hjust和nudges正确显示文本）但设置图例或标签可能是自动的。

问题2 这是一个概念性问题 - 当我调用scale_fill_manual()时，ggplot2将如何知道我是否需要垂直矩形或水平矩形的红色和蓝色？我很好奇。为什么不要求我为水平和垂直矩形提供颜色？是不是我已经使用color = forestgreen为水平矩形提供了一个恒定的颜色，所以它只需要剩下的垂直矩形对的颜色，即红色和蓝色？

我是初学者，所以如果我的问题对你们这些人来说太基本了，我很抱歉。我很感激任何帮助。

更新

这是数据的输入：

structure(list(name = c("Nixon", "Ford", "Carter", "Reagan", 
"Bush", "Clinton", "Bush", "Obama"), start = structure(c(-346L, 
1681L, 2576L, 4037L, 6959L, 8420L, 11342L, 14264L), class = "Date"), 
    end = structure(c(1681L, 2576L, 4037L, 6959L, 8420L, 11342L, 
    14264L, 17186L), class = "Date"), party = c("Republican", 
    "Republican", "Democratic", "Republican", "Republican", "Democratic", 
    "Republican", "Democratic")), .Names = c("name", "start", 
"end", "party"), row.names = c(NA, -8L), class = c("tbl_df", 
"tbl", "data.frame"))

经济数据可通过ggplot2包

公开获取

 head(economics)
# A tibble: 6 x 6
        date   pce    pop psavert uempmed unemploy
      <date> <dbl>  <int>   <dbl>   <dbl>    <int>
1 1967-07-01 507.4 198712    12.5     4.5     2944
2 1967-08-01 510.5 198911    12.5     4.7     2945
3 1967-09-01 516.3 199113    11.7     4.6     2958
4 1967-10-01 512.9 199311    12.5     4.9     3143
5 1967-11-01 518.1 199498    12.5     4.7     3066
6 1967-12-01 525.8 199657    12.1     4.8     3018

Answer 1

presidential <- subset(presidential, start > economics$date[1])
ggplot(economics) +
       geom_rect(
         aes(xmin = start, xmax = end, fill = party),
         ymin = -Inf, ymax = Inf, alpha = 0.2,
         data = presidential
       ) +
       geom_vline(
         aes(xintercept = as.numeric(start)),
         data = presidential,
         colour = "grey50", alpha = 0.5
       ) +
       geom_text(
         aes(x = start, y = 2500, label = name),
         data = presidential,
         size = 3, vjust = 0, hjust = 0, nudge_x = 50, check_overlap = TRUE
       ) +
       geom_line(aes(date, unemploy)) +
       geom_rect(
         aes(xmin = start, xmax = end, fill = "chartreuse"),
         ymin = 10000, ymax = Inf, alpha = 0.4,
         data = presidential
       ) +
       geom_text(
         aes(x = as.Date("1993-01-20"), y = 12000, label = "High unemployment"),
         size = 3, vjust = 0, hjust = 0, color = "forestgreen"
       )+
       scale_fill_manual(values = c("chartreuse", "red", "blue"), labels=c("High Unemployment","Democrat","Republican"))+labs(fill="")

就你的第二个问题而言，颜色是垂直方向映射的，因为你的初始调用......

geom_rect(
         aes(xmin = start, xmax = end, fill = party),
         ymin = -Inf, ymax = Inf, alpha = 0.2,
         data = presidential
       )

...标识start日期矩形的开始及其end日期的结束，但对于y轴，尺寸设置为Inf因此颜色垂直映射。

在ggplot2

1 个答案: