How do I add multiple x axis underneath bar graph in r using ggplot2?

Question

I'm having trouble adding in multiple x axis underneath a bar chart in RStudio using ggplot2. I want it to look something like this:

This is my current code:

ggplot(data=relative_trimming_subset, aes(x=Relative_trimming, y=Stage1_time, fill=Trimming)) +
    geom_bar(stat="identity", position=position_dodge(), show.legend = FALSE) + 
    scale_fill_manual(values = c("#cccccc", "#666666", "#cccccc", "#666666")) +
    scale_x_discrete(limits = level_order) +
    theme_bw() +
    labs(x = "Trimming") +                             
    labs(y = "Stage one time (seconds)") +  
    theme(axis.title.x=element_blank(),
          axis.text.x=element_blank(),
          axis.ticks.x=element_blank(),
          panel.grid.major = element_blank(), 
          panel.grid.minor = element_blank()) +
    theme(panel.border = element_rect(linewidth = 1)) +
    theme(text = element_text(size = 12),
          axis.title.y = element_text(margin = margin(t = 0, r = 10, b = 0, l = 0)),
          axis.line = element_line(colour = 'black'),
          axis.title = element_text(face="bold"),
          axis.text.y = element_text(size = 10),
          axis.text = element_text(colour = 'black'))

I have tried using the annotate function as laid out here: https://statisticsglobe.com/draw-plot-multi-row-x-axis-labels-r

I have also tried using geom_text, but can't seem to get it to work. If anyone has any advice, that would be great! Feels like it should be simple but I've spent hours on it now...

Thank you.

Reproducible subset of my data:

structure(list(ID = c("TF1-05MB", "TF1-05MB", "TF1-05MB", "TF1-05MB", 
"TF1-05MB", "TF1-05MB", "TF1-05MB", "TF1-05MB", "TF1-05MB", "TF1-05MB", 
"TF1-05MB", "TF1-05MB", "TF1-05MB", "TF1-05MB", "TF1-05MB", "TF1-07MB", 
"TF1-07MB", "TF1-07MB", "TF1-07MB", "TF1-07MB", "TF1-07MB", "TF1-07MB", 
"TF1-07MB", "TF1-07MB", "TF1-07MB", "TF1-07MB", "TF1-07MB", "TF1-07MB", 
"TF1-07MB", "TF1-07MB"), Sex = c("M", "M", "M", "M", "M", "M", 
"M", "M", "M", "M", "M", "M", "M", "M", "M", "M", "M", "M", "M", 
"M", "M", "M", "M", "M", "M", "M", "M", "M", "M", "M"), Trimming = c("Untrimmed_full", 
"Untrimmed_full", "Untrimmed_full", "Untrimmed_full", "Untrimmed_full", 
"Untrimmed_full", "Untrimmed_full", "Untrimmed_full", "Trimmed_full", 
"Trimmed_full", "Trimmed_full", "Trimmed_full", "Trimmed_full", 
"Trimmed_full", "Trimmed_full", "Untrimmed_control", "Untrimmed_control", 
"Untrimmed_control", "Untrimmed_control", "Untrimmed_control", 
"Untrimmed_control", "Untrimmed_control", "Untrimmed_control", 
"Trimmed_control", "Trimmed_control", "Trimmed_control", "Trimmed_control", 
"Trimmed_control", "Trimmed_control", "Trimmed_control"), Relative_trimming = c("Pre", 
"Pre", "Pre", "Pre", "Pre", "Pre", "Pre", "Pre", "Post", "Post", 
"Post", "Post", "Post", "Post", "Post", "Pre", "Pre", "Pre", 
"Pre", "Pre", "Pre", "Pre", "Pre", "Post", "Post", "Post", "Post", 
"Post", "Post", "Post"), Day = c(1L, 1L, 1L, 1L, 2L, 2L, 2L, 
2L, 3L, 3L, 3L, 3L, 4L, 4L, 4L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 
3L, 3L, 3L, 3L, 4L, 4L, 4L), Trial_number = c(1L, 2L, 3L, 4L, 
1L, 2L, 3L, 4L, 1L, 2L, 3L, 4L, 2L, 3L, 4L, 1L, 2L, 3L, 4L, 5L, 
1L, 2L, 3L, 1L, 2L, 4L, 5L, 1L, 2L, 5L), Reaction_time = c(40L, 
3L, 37L, 5L, 5L, 5L, 5L, 16L, 8L, 13L, 12L, 7L, 5L, 6L, 6L, 3L, 
6L, 6L, 6L, 6L, 17L, 13L, 13L, 9L, 14L, 13L, 12L, 5L, 6L, 5L), 
    Stage1_time = c(5L, 5L, 4L, 8L, 5L, 7L, 5L, 8L, 6L, 5L, 7L, 
    5L, 5L, 8L, 5L, 7L, 7L, 7L, 6L, 8L, 6L, 7L, 7L, 4L, 5L, 5L, 
    16L, 6L, 8L, 6L), PC1_score = c(-0.080373226, 0.032477537, 
    -0.155069158, 0.1965224, -0.139819473, -0.013115389, -0.069847159, 
    0.045855081, -0.090945817, -0.118591067, 0.028014289, -0.075510197, 
    -0.02157794, 0.118944384, -0.065654084, 0.102907134, -0.04347041, 
    -0.062195986, 0.028970608, 0.045541099, 0.025417646, 0.074033332, 
    0.117344171, -0.083718399, -0.029333778, -0.104413751, -0.133641797, 
    -0.020064955, 0.081972399, -0.014783332), S_length = c(3.274, 
    3.274, 3.274, 3.274, 3.274, 3.274, 3.274, 3.274, 3.274, 3.274, 
    3.274, 3.274, 3.274, 3.274, 3.274, 3.254, 3.254, 3.254, 3.254, 
    3.254, 3.254, 3.254, 3.254, 3.254, 3.254, 3.254, 3.254, 3.254, 
    3.254, 3.254), D_length = c(2.028, 2.028, 2.028, 2.028, 2.028, 
    2.028, 2.028, 2.028, 2.028, 2.028, 2.028, 2.028, 2.028, 2.028, 
    2.028, 1.839, 1.839, 1.839, 1.839, 1.839, 1.839, 1.839, 1.839, 
    1.839, 1.839, 1.839, 1.839, 1.839, 1.839, 1.839), A_length = c(2.278, 
    2.278, 2.278, 2.278, 2.278, 2.278, 2.278, 2.278, 2.278, 2.278, 
    2.278, 2.278, 2.278, 2.278, 2.278, 2.077, 2.077, 2.077, 2.077, 
    2.077, 2.077, 2.077, 2.077, 2.077, 2.077, 2.077, 2.077, 2.077, 
    2.077, 2.077)), class = "data.frame", row.names = c(NA, -30L
))

Hi, can you provide a reproducible example of your dataset? https://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example — william3031, Mar 16 '23 at 03:20
@william3031 I've added a reproducible subset of my data in the question, I had to change one of the variables in the ggplot code so they match, but should work the same. — cookies5098, Mar 16 '23 at 03:29

benson23 · Accepted Answer · 2023-03-16T04:22:34.207

An easy alternative would be using facet_grid. First create a new column containing the values of Control or full, then use this column as the new x-axis. After that, play around with facet_grid and theme to set desired look of the graph.

library(ggplot2)
library(dplyr)

level_order <- c('Pre', 'Post')

ggplot(data=relative_trimming_subset %>% mutate(Trimming2 = sub(".*_", "", Trimming)), 
       aes(x=Trimming2, y=Stage1_time, fill=Trimming)) +
  geom_bar(stat="identity", position=position_dodge(), show.legend = FALSE) + 
  scale_fill_manual(values = c("#cccccc", "#666666", "#cccccc", "#666666")) +
  theme_bw() +
  labs(x = "Trimming") +                             
  labs(y = "Stage one time (seconds)") +  
  facet_grid(~ factor(Relative_trimming, levels = level_order), switch = "x") +
  theme(axis.title.x=element_blank(),
        panel.grid.major = element_blank(), 
        panel.grid.minor = element_blank(),
        text = element_text(size = 12),
        axis.title.y = element_text(margin = margin(t = 0, r = 10, b = 0, l = 0)),
        axis.line = element_line(colour = 'black'),
        axis.title = element_text(face="bold"),
        axis.text.y = element_text(size = 10),
        axis.text = element_text(colour = 'black'),
        strip.placement = "outside",
        panel.border = element_blank(),
        strip.background = element_blank())

This works great, thank you! The only thing is that I need the 'pre' to be on the left with 'post' on the right. That's what the line regarding level_order does which is specified previously (level_order <- c('Pre', 'Post') ). I've tried using the same code in the example you posted but it's not working, any ideas? Thank you so much for your help! — cookies5098, Mar 16 '23 at 04:18
@cookies5098 Remember to put that in your question as well :) Updated code, which set `factor` based on `level_order`. — benson23, Mar 16 '23 at 04:23

How do I add multiple x axis underneath bar graph in r using ggplot2?

1 Answers1