I would like to create a plot with segements or arrows.
Let's say I have this toy example
temp <- data.frame(posi=c(1,2,3,3,2,1,5), from=c("A", "B", "C", "D", "D", "B", "A"),
to=c( "C", "D", "D", "C", "A", "A", "B"))
posi from to
1 A C
2 B D
3 C D
3 D C
2 D A
1 B A
5 A B
And I want to plot segments or arrows from the points defined by "from" and its starting position to the points defined by "to" and position+1.
I got to create the plot with ggplot
ggplot() + geom_point(data=temp, aes(x=posi, y=from, size=10),show.legend = FALSE) +
geom_point(data=temp, aes(x=posi+1, y=to, size=10),show.legend = FALSE) +
geom_segment(data=temp, aes(x=posi, y=from, xend=posi+1, yend=to),
arrow=arrow(type="closed", angle=10), size=1.5, color="blue") + theme_bw()
But I would like to do it with Lattice because my real dataset is much bigger (millions of rows) and lattice works faster.
I know I can reduce the number of lines removing duplicates but that's another story.
How can I do it with lattice?
I've been researchig and I think I need to use a panel.segments or lsegments, but things seem to be much more complicated and it's difficult to find examples.
xyplot(from ~ posi , type="p", col="black", data=temp, pch=16,
panel = function(x, y, ...){ panel.segments(x,y,) })
I don't know what parameters to write inside function nor inside panel.
![](https://www.manongdao.com/static/images/pcload.jpg)
You could use the following code:
xyplot(from ~ posi , type="p", col="black", data=temp, pch=16, xlim = c(0,7),
panel = function(...){
panel.dotplot(x = (temp$posi+1), y = temp$to, col="black", cex=1.4)
panel.dotplot(x = temp$posi, y = temp$from, col ="black", cex=1.4)
panel.arrows(x0 = temp$posi, y0 = temp$from, x1 = temp$posi+1, y1 = temp$to, lwd=3, col="blue", )
}
)
yielding the following graph:
![](https://www.manongdao.com/static/images/pcload.jpg)
Please let me know whether this is what you want.
UPDATE
I posted a question concerning the problem that @skan identified and described in the comments: when a "extreme" level (like "D") is not present in temp$from
then the "D" will not part of the graph, even when "D" will be needed later for temp$to
. The question with answer from @Konn may be found here.
As I understand it now, we need a factor
that is ordered
, and we need an addition to the code specifying drop.unused.levels = FALSE
in the call to xyplot
. In the example we show the full set with "extremes" in "from" and as subset where the extreme "D" is absent: The full code is:
l <- c("A", "B", "C", "D")
temp <- data.frame(posi = c(1, 2, 3, 3, 2),
from= factor(c("A", "B", "C", "D", "D"), levels = l, ordered = TRUE),
to = factor(c("C", "D", "D", "C", "A"), levels = l, ordered = TRUE)
)
xyplot(from ~ posi , type="p", col="black", data=temp, pch=16, xlim = c(0,7),
drop.unused.levels = FALSE, ## the added code
panel = function(...){
panel.dotplot(x = temp$posi, y = temp$from, col ="green", cex=1.6)
panel.dotplot(x = (temp$posi+1), y = temp$to, col="black", cex=1.)
panel.arrows(x0 = temp$posi, y0 = temp$from, x1 = temp$posi+1, y1 = temp$to, lwd=2, col="blue" )
})
temp <- temp[1:3, ]
xyplot(from ~ posi , type="p", col="black", data=temp, pch=16, xlim = c(0,7),
drop.unused.levels = FALSE, ## the added code
panel = function(...){
panel.dotplot(x = temp$posi, y = temp$from, col ="green", cex=1.6)
panel.dotplot(x = (temp$posi+1), y = temp$to, col="black", cex=1.)
panel.arrows(x0 = temp$posi, y0 = temp$from, x1 = temp$posi+1, y1 = temp$to, lwd=2, col="blue" )
})
yielding the following pics:
![](https://www.manongdao.com/static/images/pcload.jpg)
![](https://www.manongdao.com/static/images/pcload.jpg)
I think we have solved this question.