如何在ggplot2中绘制两条线
这似乎与 Hadley 的 ggplot2 书中的一些示例类似，但我似乎无法完成这项工作。 给定：
off = c(0, 2000, 4000, 6000, 25, 3000, 6050, 9000)
tim = c( 0, -100, -200, -300 -25, -125, -225, -325)
col = c( 1, 1, 1, 1, 2, 2, 2, 2)
dataf = data.frame(off, tim, col)
p = ggplot(dataf, aes(off, tim, color=col)) + geom_point() + geom_line()
p
我认为这应该绘制这八个点，并用 col = 1 绘制一条穿过前四个点的线，用 col = 2 绘制另一条穿过最后四个点的线。然而我最终得到的是一条红色和蓝色交替的线段。
为什么？！
This seems to be a similar example to some of Hadley's examples in his ggplot2 book, but I can't seem to make this work.
Given:
off = c(0, 2000, 4000, 6000, 25, 3000, 6050, 9000)
tim = c( 0, -100, -200, -300 -25, -125, -225, -325)
col = c( 1, 1, 1, 1, 2, 2, 2, 2)
dataf = data.frame(off, tim, col)
p = ggplot(dataf, aes(off, tim, color=col)) + geom_point() + geom_line()
p
I think this should plot these eight points and draw ONE line through the first four points with col = 1 and another line through the last four points with col = 2. Yet what I end up with is one line with alternating red and blue segments.
Why?!
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因为
col是数字。分组设置为因子变量的交互作用，但由于没有因子变量，因此将线绘制为单个组。您可以将col更改为一个因子，或手动设置分组
Because
colis numeric. Grouping is set to the interaction of factor variables, but since there are none the line is plotted as a single group. You can either changecolto a factor,or manually set the grouping