ggplot2: how to fix the order of the x axis of a geom_bar - axis

Question

I'm new to R. I've produced a bar chart using ggplot2; however, when it plots, the order of the months change along the x axis. I am not sure how to write the code to prevent this from happening and to get the months in the correct order along the x axis.
df <-
data.frame(
month = c(
"May",
"June",
"July",
"August",
"September",
"October",
"November"
),
cpue = c(2.40, 4.20, 6.16, 5.25, 3.32, 2.33, 0.91)
)
ggplot(data = df, aes(x = month, y = cpue)) +
geom_bar(stat = "identity", width =
0.5, fill = "black") + labs(x = "Month", y = "CPUE") + theme(
axis.text = element_text(size = 12),
axis.title = element_text(size = 14),
axis.line = element_line(colour = "black"),
panel.grid.major = element_blank()
)

Answer 1

It is not randomly changing the x axis, but instead it is trying to put the x-axis in an alphabetical order.
An easy fix to this is to make your df ordered using levels.
df <- data.frame(month=c("May","June","July","August","September","October","November"),cpue=c(2.40,4.20,6.16,5.25,3.32,2.33,0.91))
Now that your df is made, we can easily level the column, we will use for the x-axis, in this case the month column:
df$month <- factor(df$month, levels = df$month)
Now, when we plot the bar graph, it is in the order we provided it with from the data frame.
ggplot(data=df,aes(x=month,y=cpue)) +
geom_bar(stat="identity",width=0.5,fill="black") +
labs(x="Month",y="CPUE") +
theme(axis.text=element_text(size=12),axis.title=element_text(size=14),axis.line=element_line(colour="black"),panel.grid.major = element_blank())
Hopefully this helps!

Answer 2

Another option is to use fct_inorder from forcats (part of tidyverse) to keep the original order of the data.
library(tidyverse)
ggplot(data = df, aes(x = fct_inorder(month), y = cpue)) +
geom_bar(stat = "identity", width =
0.5, fill = "black") + labs(x = "Month", y = "CPUE") + theme(
axis.text = element_text(size = 12),
axis.title = element_text(size = 14),
axis.line = element_line(colour = "black"),
panel.grid.major = element_blank()
)
Output

Answer 3

You can also try to use reorder within the ggplot. It allows you to reorder one variable based on another variable, like this:
library(tidyverse)
ggplot(data = df, aes(x = reorder(month, cpue), y = cpue))
Or if you want it in descending order, just add a minus, like this:
ggplot(data = df, aes(x = reorder(month, -cpue), y = cpue))