How to plot a bar plot by ggplot2 and sort bars in non-alphabetical order

Question

I'm trying to plot a boxplot by ggplot2 and it sorts the boxes in alphabetical order, but I want to change their order. How can I do that?

Thanks for any help.

Here is my code:

mydata <- data.frame(DRG=c(12,23,15,60,2),
                     XPA=c(30,25,55,70,63),
                     SHO=c(22,15,34,23,14),
                     ALA=c(120,95,113,126,103))
row.names(mydata) <- c("sample1","sample2","sample3","sample4","sample5")
mydata <- t(mydata)
mydata <- as.data.frame(mydata)

b.plot <- ggplot(data=mydata, aes(x=row.names(mydata), y=sample1)) +
  geom_bar(stat="identity" , color="green" , fill="yellowgreen", position="dodge" , width = 0.5) +
  xlab("Genes") +
  ylab("Expression") +
  theme(axis.text.x = element_text(size = 10, angle = 45, hjust = 1), 
        plot.margin = margin(0.5,0.5,0.5,2, "cm"))
b.plot

Just as a note: `fct_relevel` is not provided as an answer in those sites indicated as duplicates. — TarJae, Dec 26 '21 at 10:13

score 3 · Accepted Answer · answered Dec 26 '21 at 09:54

We could use fct_relevel from forcats package (it is in tidyverse).

Bring your rownames to a column gene with rownames_to_column function from tibble package (it is in tidyverse)
Use fct_relevel to set the order as you wish
Then use ggplot2 (I used geom_col())

library(tidyverse)

mydata %>% 
  rownames_to_column("gene") %>% 
  pivot_longer(
    cols = -gene
  ) %>% 
  mutate(gene = fct_relevel(gene, 
                            "SHO", "DRG", "ALA", "XPA")) %>% 
  ggplot(aes(x=gene, y=value))+
  geom_col(color="green" , fill="yellowgreen", position="dodge" , width = 0.5)+
  xlab("Genes")+
  ylab("Expression") +
  theme(axis.text.x = element_text(size = 10, angle = 45, hjust = 1), 
        plot.margin = margin(0.5,0.5,0.5,2, "cm"))

AndrewGB · Answer 2 · 2021-12-26T17:12:51.780

2

You can set x to be a factor, then use levels to set the order that you want.

library(tidyverse)

ggplot(data = mydata, aes(x = factor(
  row.names(mydata),
  levels = c("DRG", "XPA", "SHO", "ALA")
), y = sample1)) +
  geom_bar(
    stat = "identity" ,
    color = "green" ,
    fill = "yellowgreen",
    position = "dodge" ,
    width = 0.5
  ) +
  xlab("Genes") +
  ylab("Expression") +
  theme(
    axis.text.x = element_text(
      size = 10,
      angle = 45,
      hjust = 1
    ),
    plot.margin = margin(0.5, 0.5, 0.5, 2, "cm")
  )

Output

edited Dec 26 '21 at 17:12

answered Dec 26 '21 at 08:00

AndrewGB

16,126
5
18
49

Dear Andrew, thanks for your reply. I've converted `x` to a factor and only labels were changed, but I want to reorder the **boxes** with **their** **labels** and not only the labels. – zahra abdi Dec 26 '21 at 08:46
1

Andrew, you need to set levels – tjebo Dec 26 '21 at 09:22
@zahraabdi I meant `levels`, not `labels`. I've updated the answer to reflect that. Sorry, it was late! – AndrewGB Dec 26 '21 at 17:13

How to plot a bar plot by ggplot2 and sort bars in non-alphabetical order

2 Answers2