ggplot2:将线宽应用于图例键

Question

考虑data.frame"dfc":

dfc <- structure(list(lag = c(-5L, -4L, -3L, -2L, -1L, 0L, 1L, 2L, 3L, 
       4L, 5L, -5L, -4L, -3L, -2L, -1L, 0L, 1L, 2L, 3L, 4L, 5L), variable = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L), .Label = c("var1", "var2"), class = "factor"), 
value = c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 0.6, 1.2, 1.8, 
2.4, 3, 3.6, 4.2, 4.8, 5.4, 6, 6.6), size = c(2, 2, 2, 2, 
2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)), .Names = c("lag", 
"variable", "value", "size"), row.names = c(NA, -22L), class = "data.frame")

看起来像:

head(dfc)
  lag variable value size
1  -5     var1     1    2
2  -4     var1     2    2
3  -3     var1     3    2
4  -2     var1     4    2
5  -1     var1     5    2
6   0     var1     6    2

我想用不同的线条样式(取决于"变量"和宽度(取决于"大小"))对"滞后"绘制"值".我用这段代码实现了:

ggplot(dfc) +
geom_line(aes(x = lag, y = value, linetype = variable, size = size)) +
scale_size(range=c(1, 2), guide=FALSE) +
scale_linetype_manual(values = 1:2, labels = c("Name of var1    ", "Name of var2")) +
theme(legend.title = element_blank(), legend.position = "bottom",
      legend.direction = "horizontal")

给出这个情节:

但是我无法弄清楚如何相应地改变图例中线条的大小,并保持重命名.

Answer 1

z <- ggplot(dfc) + 
     geom_line(aes(x = lag, y = value, linetype = variable, size = size)) + 
     scale_size(range=c(1, 2), guide=FALSE)
z <- z + theme(legend.key.width = unit(5,"cm"))
z <- z + guides(linetype = guide_legend(override.aes = list(size = 2)))
z

我已将该guides()功能添加到我之前的答案中.

增加宽度后legend.key.width,可以使用override.aes参数更改图例中线条的大小并将其指定给linetype变量.

这可能是@cogitovita提出的其他方式.