How to create an individual line plot in between box plot in r

Question

I'm trying to create a plot like this image below where the individual data lines are in between the box plots. Image to create in R ggplot2

The closest I am getting is something like this: Image using ggplot2 but it looks a bit cluttered with the lines/points behind.

data1 %>%
ggplot(aes(Time,Trait)) +
geom_line(aes(group=ID), position = "identity")+
geom_point(aes(group=ID), shape=21, colour="black", size=2, position = "identity")+
geom_boxplot(width=.5,position = position_dodge(width=0.9), fill="white") +
stat_summary(fun.data= mean_cl_boot, geom = "errorbar", width = 0.1,  position = position_dodge(width = .9)) +
stat_summary(fun = mean, geom = "point", shape = 18, size=3, position = "identity")+
facet_wrap(~Cond) +
theme_classic()

Any tips would be greatly appreciated!

Hello Erich, very nice question. Could you post part of your data? — LDT, Aug 03 '21 at 21:47
Previous related discussion - https://stackoverflow.com/questions/15605926/how-to-draw-a-plot-joining-points-from-two-measurement-times/15606055 — thelatemail, Aug 03 '21 at 23:17

stefan · Accepted Answer · 2021-08-04T13:37:28.753

One option to achieve your desired result would be to make use of continuous x scale. Doing so makes it possible to shift the box plots to the left or to right and vice versa for the points and lines:

Making use of some random data to mimic your real data set.


data1$Time1 <- as.numeric(factor(data1$Time, levels = c("Pre", "Post")))
data1$Time_box <- data1$Time1 + .1 * ifelse(data1$Time == "Pre", -1, 1)
data1$Time_lp <- data1$Time1 + .1 * ifelse(data1$Time == "Pre", 1, -1)

library(ggplot2)
ggplot(data1, aes(x = Time_box, y = Trait)) +
  geom_line(aes(x = Time_lp, group=ID), position = "identity")+
  geom_point(aes(x = Time_lp, group=ID), shape=21, colour="black", size=2, position = "identity")+
  geom_boxplot(aes(x = Time_box, group=Time1), width=.25, fill="white") +
  stat_summary(fun.data = mean_cl_boot, geom = "errorbar", width = 0.1) +
  stat_summary(fun = mean, geom = "point", shape = 18, size=3, position = "identity") +
  scale_x_continuous(breaks = c(1, 2), labels = c("Pre", "Post")) +
  facet_wrap(~Cond) +
  theme_classic()

DATA

set.seed(42)

data1 <- data.frame(
  ID = rep(1:10, 4),
  Time = rep(c("Pre", "Post"), each = 10),
  Trait = runif(40),
  Cond = rep(c("MBSR", "SME"), each = 20)
)

EDIT If you want to two boxplots side by side it's basically the same. However in that case you have to map the interaction of Time1 and the variable mapped on fill on the group aesthetic in geom_boxplot (and probably the error bars as well):

library(ggplot2)

set.seed(42)

data1 <- data.frame(
  ID = rep(1:10, 4),
  Time = rep(c("Pre", "Post"), each = 10),
  Fill = rep(c("Fill1", "Fill2"), each = 5),
  Trait = runif(40),
  Cond = rep(c("MBSR", "SME"), each = 20)
)

ggplot(data1, aes(x = Time_box, y = Trait)) +
  geom_line(aes(x = Time_lp, group=ID, color = Fill), position = "identity")+
  geom_point(aes(x = Time_lp, group=ID, fill = Fill), shape=21, colour="black", size=2, position = "identity")+
  geom_boxplot(aes(x = Time_box, group=interaction(Time1, Fill) , fill = Fill), width=.25) +
  stat_summary(fun.data = mean_cl_boot, geom = "errorbar", width = 0.1) +
  stat_summary(fun = mean, geom = "point", shape = 18, size=3, position = "identity") +
  scale_x_continuous(breaks = c(1, 2), labels = c("Pre", "Post")) +
  facet_wrap(~Cond) +
  theme_classic()

Thank you so much for the speedy response! Very helpful. Works great! Now if I want to add another boxplot (fill group) to each pre/post (so it appears in the legend), how would I do this? position_dodge doesn't seem to work with the boxplot... — Erich, Aug 04 '21 at 13:19
Basically it's the same. But you have to set the `group`ing right to make it work. — stefan, Aug 04 '21 at 13:38

How to create an individual line plot in between box plot in r

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