There are many questions on here about how to get a certain line or point to plot at the top of your data in ggplot2. Currently the way to do this is different for geom_point (which depends on the actual order of the data.frame) and geom_line (which depends on the factor levels).
I am wondering if anyone knows why they are different and if there is any plan to change them. I am hoping if I know why then it can help make it more memorable because currently every time I want to alter plotting order I just end up getting frustrated.
I have made an example to illustrate the point based on this question from years ago
Change the overlaying order of lines in ggplot
Please note I am not asking how to do this (you can see below I know how to do it) but to get more understanding of why it is like this (therefore I don't think this question is a duplicate as far as I can see)
library(ggplot2)
#data
pl_data <- structure(list(x = c(1, 1.5, 2, 1, 1.3, 1.4, 1.51, 2, 1, 1.31, 2),
y = c(0, 0.5, 1, 1, 0.7, 0.7, 0.5, 0, 0.7, 0.7, 0.7),
col = c("r", "r", "r", "b", "b", "b", "b", "b", "g", "g", "g")),
row.names = c(NA, -11L), class = c("tbl_df", "tbl", "data.frame"))
#starting plot
plt1 <- ggplot(pl_data, aes(x = x, y = y, color = col)) +
geom_line(size = 3)+
scale_colour_manual(values = c("r"="Red","b"="blue","g"="green"))
#change factor to change lines
pl_data2 <- pl_data
pl_data2$col <- factor(pl_data2$col, c("g", "r", "b"))
plt2 <- plt1 %+% pl_data2
#But the points are still the same way around as in original
plt1 + geom_point(size = 5)
plt2 + geom_point(size = 5)
#reorder data to chnage the points
pl_data3 <- pl_data2[order(pl_data2$col),]
plt3 <- plt1 %+% pl_data3
plt3+ geom_point(size = 5)
Created on 2019-11-12 by the reprex package (v0.3.0)
