使用线型和组美学的ggplot错误

Question

我正在尝试根据以下数据制作情节

dt <- data.frame(ValuationDate = seq.Date(as.Date("2014-1-1"), 
                 as.Date("2014-7-1"), by = "month"), 
                 Adjuster = factor(c("Bob","Bob","Sue","Sue","Sue","Sue","Bob")),
                 Paid = c(1,2,3,4,5,6,7), Incurred = c(3,5,9,9,10,8,7))
dt <- melt(dt, measure.vars = c("Paid", "Incurred"), 
           variable.name = "Value", value.name = "Amount")
dt
   ValuationDate Adjuster    Value Amount
1     2014-01-01      Bob     Paid      1
2     2014-02-01      Bob     Paid      2
3     2014-03-01      Sue     Paid      3
4     2014-04-01      Sue     Paid      4
5     2014-05-01      Sue     Paid      5
6     2014-06-01      Sue     Paid      6
7     2014-07-01      Bob     Paid      7
8     2014-01-01      Bob Incurred      3
9     2014-02-01      Bob Incurred      5
10    2014-03-01      Sue Incurred      9
11    2014-04-01      Sue Incurred      9
12    2014-05-01      Sue Incurred     10
13    2014-06-01      Sue Incurred      8
14    2014-07-01      Bob Incurred      7

对于每个ValuationDate，有一个“付费”金额和一个“发生”金额我想在一段时间内绘制，将每个时间段与一个调整器相关联。当我尝试做

时

#with grouping variable and linetype (error)
ggplot(data = dt) + geom_step(aes(x = ValuationDate, 
                                  y = Amount, group = Value, 
                                  color = Adjuster, linetype = Value))

我得到“错误：geom_path：如果你使用虚线或虚线，颜色，大小和线型必须在线上保持不变”

然而，以下两个图表工作

#with grouping variable, without linetype
ggplot(data = dt) + geom_step(aes(x = ValuationDate, y = Amount,
                                  group = Value, color = Adjuster))

#with linetype, without grouping variable
ggplot(data = dt) + geom_step(aes(x = ValuationDate, y = Amount,
                                  color = Adjuster, linetype = Value))

是什么给出了？

Answer 1

让我们看一下产生错误的piece of code：

# Work out whether we should use lines or segments
attr <- ddply(munched, .(group), function(df) {
  data.frame(
    solid = identical(unique(df$linetype), 1),
    constant = nrow(unique(df[, c("alpha", "colour","size", "linetype")])) == 1
  )
})
solid_lines <- all(attr$solid)
constant <- all(attr$constant)
if (!solid_lines && !constant) {
  stop("geom_path: If you are using dotted or dashed lines",
    ", colour, size and linetype must be constant over the line",
    call.=FALSE)
}

因此，如果至少有两个不同的linetype s，则所有其他aes应该是唯一的。我不能说为什么会出现这种限制，可能会导致一些与渲染相关的问题。

您可以通过其他方式区分线条，例如改变size或alpha而不是linetype。另一种可能性是添加

geom_point(aes(x = ValuationDate, y = Amount, group = Value, shape = Value), size = 3)

Answer 2

您必须为每个唯一的值x调整器段使用单独的geom_step调用。

gg <- ggplot()
for (i in 1:6) gg <- gg + 
  geom_step(data=subset(your_dt, Segment==i), 
            aes(x=ValuationDate, y=Amount, color=Adjuster, linetype=Value, group=i))

制作（致电gg）：

要使其连接到连续的阶梯线（即您想要的输出），您必须插入一些虚拟/重复行。我是手动完成的，但根据您执行此操作的频率，您可能需要一个函数来插入这些行。通过将Adjuster和Value与前一行进行比较，可以轻松计算Segment。

your_dt：

   ValuationDate Adjuster    Value Amount DummyRow Segment
1       1/1/2014      Bob     Paid      1       no       1
2       2/1/2014      Bob     Paid      2       no       1
3       3/1/2014      Bob     Paid      2      yes       1
4       3/1/2014      Sue     Paid      2      yes       2
5       3/1/2014      Sue     Paid      3       no       2
6       4/1/2014      Sue     Paid      4       no       2
7       5/1/2014      Sue     Paid      5       no       2
8       6/1/2014      Sue     Paid      6       no       2
9       7/1/2014      Sue     Paid      6      yes       2
10      7/1/2014      Bob     Paid      6      yes       3
11      7/1/2014      Bob     Paid      7       no       3
12      1/1/2014      Bob Incurred      3       no       4
13      2/1/2014      Bob Incurred      5       no       4
14      3/1/2014      Bob Incurred      5      yes       4
15      3/1/2014      Sue Incurred      5      yes       5
16      3/1/2014      Sue Incurred      9       no       5
17      4/1/2014      Sue Incurred      9       no       5
18      5/1/2014      Sue Incurred     10       no       5
19      6/1/2014      Sue Incurred      8       no       5
20      7/1/2014      Sue Incurred      8      yes       5
21      7/1/2014      Bob Incurred      8      yes       6
22      7/1/2014      Bob Incurred      7       no       6