CODEWITHSUNDEEP
rggplot2tidyverse
Flavien PETIT
Flavien PETIT

Reputation: 106

How to use geom_bar and use two categorical variables on the x axis

I try to do a bar plot, with an X axis a bit different than usual. The idea is to represent this axis by the initial variable (code) and by a grouping variable (region). Each code has one region attributed to it. And I would like vertical line to delimitate my regions on the plot.

Here is a reprex

library(dplyr)
library(ggplot2)
data <- tibble::tribble(
                           ~code,    ~term,          ~estimate,           ~std.error,       ~statistic,             ~p.value,      ~region,
                          "ANTA", "t_chla", 0.0577051712200805, 0.000720537559840254, 80.0862778518777, 1.51491004165028e-36,      "Polar",
                          "ARCH", "t_chla", 0.0528096415790542,  0.00237431411186973, 22.2420619559337, 9.38778083531695e-08, "Equatorial",
                          "ARCT", "t_chla", 0.0381489725623347, 0.000549351930679462, 69.4435942277484,  7.1661522966813e-84,      "Polar",
                          "BPLR", "t_chla", 0.0334314725309052, 0.000908084662707285, 36.8153696498248,   6.728272457306e-26,      "Polar",
                          "EMED", "t_chla",  0.048713647973686,  0.00179735526256328, 27.1029601038437, 1.37127584382531e-20,  "Temperate",
                          "SANT", "t_chla", 0.0311278181792805, 0.000594175450783383, 52.3882602996143, 4.93281235468381e-67,      "Polar",
                          "SPSG", "t_chla", 0.0676467149977894,  0.00461643829029263,  14.653442923744, 1.64755108560374e-06, "Equatorial",
                          "WMED", "t_chla", 0.0359293074812375, 0.000954627809780489, 37.6369796826883, 1.88418982949485e-42,  "Temperate"
                          )

data$code <- factor(data$code, levels = c("ANTA", "SANT", "ARCT", "BPLR", "EMED", "WMED", "SPSG", "ARCH"))


ggplot(data)+
  geom_bar(aes(y = estimate, x = code, fill = code), stat = "identity")+
  geom_errorbar(aes(ymin = estimate - std.error, ymax = estimate + std.error, x = code))+
  scale_fill_brewer(palette = "Set1", guide = "none")+
  theme_bw()+
  ylab("Specifc absorption")+
  xlab("Oceanic province")+
  ggtitle("Specific absorption")

enter image description here

So the idea is to have a vertical line between BPLR and EMED and between WMED and SPSG, with the bar grouped under the label Polar, Temperate and Equatorial.

Thanks in advance for your answers.

Upvotes: 2

Views: 1229

Answers (1)

nniloc
nniloc

Reputation: 4243

What about adding facet_wrap and panel.spacing = unit(0, 'lines') to your plot?

ggplot(data)+
  geom_bar(aes(y = estimate, x = code, fill = code), stat = "identity")+
  geom_errorbar(aes(ymin = estimate - std.error, ymax = estimate + std.error, x = code))+
  scale_fill_brewer(palette = "Set1", guide = "none")+
  theme_bw()+
  ylab("Specifc absorption")+
  xlab("Oceanic province")+
  ggtitle("Specific absorption") +
  facet_wrap(~region, scales = 'free_x') +
  theme(panel.spacing = unit(0, 'lines'))

enter image description here

Edit: updated to manually add vertical line and labels

Here is another option for adding the grouping to the bars. Lots of customization can be done with text size, position, color, font, etc.

ggplot(data)+
  geom_bar(aes(y = estimate, x = code, fill = code), stat = "identity")+
  geom_errorbar(aes(ymin = estimate - std.error, ymax = estimate + std.error, x = code))+
  scale_fill_brewer(palette = "Set1", guide = "none")+
  theme_bw()+
  ylab("Specifc absorption")+
  xlab("Oceanic province")+
  ggtitle("Specific absorption") +
  geom_vline(xintercept = c(4.5, 6.5)) +
  annotate(geom = 'text', x = 2.5, y = .07, label = 'Polar') +
  annotate(geom = 'text', x = 5.5, y = .07, label = 'Temperate') +
  annotate(geom = 'text', x = 8, y = .07, label = 'Equitorial')

enter image description here

Upvotes: 2

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