Ggplot: multiple lines starting at the same point
I have a dataset like this one:
df <- data.frame(Species = c("Sp A", "Other sp", "Other sp", "Other sp",
"Sp A", "Other sp", "Other sp"),
Study = c("A", "A", "A", "A",
"B", "B", "B"),
Value = c(1, 3, 4, 5, 3, 6, 7))
Looks like:
> df
Species Study Value
1 Sp A A 1
2 Other sp A 3
3 Other sp A 4
4 Other sp A 5
5 Sp A B 3
6 Other sp B 6
7 Other sp B 7
I would like to compare values of view A with values of other views from the same study.
This is the plot I have now:
ggplot(df, aes(y = Value, x = Species)) +
geom_point(shape = 1) +
geom_line(aes(group = Study), color = "gray50") +
theme_bw()
I don't want vertical lines. Instead, I would like to have 5 lines starting from the bottom "Sp A" towards 3 corresponding "other sp" points from the same study (A) and 2 starting from the top "Sp A" towards 2 other points from that same study (B).
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There might be a more elegant way to do this, but here's a solution that works. The trick is to change the data a bit and then use geom_segment
:
library(tidyverse)
df <- data.frame(Species = c("Sp A", "Other sp", "Other sp", "Other sp",
"Sp A", "Other sp", "Other sp"),
Study = c("A", "A", "A", "A",
"B", "B", "B"),
Value = c(1, 3, 4, 5, 3, 6, 7))
# Split data
other <- df %>% filter(Species == "Other sp")
sp_a <- df %>% filter(Species == "Sp A")
# Recombine into the data set for plotting
df <- other %>%
inner_join(sp_a, by = "Study")
# Make the plot
ggplot(df, aes(x = Species.y, y = Value.y)) +
geom_segment(aes(xend = Species.x, yend = Value.x, colour = Study))
Adjust the schedule as desired!
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You can do this with geom_line
if for each level Study
you duplicate the number of lines Sp A
to match the number of lines Other sp
and then assign a unique ID to each pair Sp A
and Other sp
for aesthetics group
.
library(tidyverse)
df %>% group_by(Study) %>%
slice(c(rep(1,length(Species[Species=="Other sp"])),2:n())) %>%
group_by(Study, Species) %>%
mutate(ID = paste0(Study, 1:n())) %>%
ggplot(aes(y = Value, x=Species, group=ID, colour=Study)) +
geom_point(shape=1) +
geom_line() +
theme_bw()
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