Choosing ordering for labels in geometric bar plot

Question

I am trying to visualize qualitative grade based data, and I would like to order the grades from worst to best. The current ordering seems to be lexicographic one. How can I change this? Unfortunately I do not know how to share a working example: the column G3.x is full of letter based qualitative grades. When I tried the code with an example test_data <- c("Excellent", "Very Good", "Good", "Sufficient", "Weak", "Poor") I get errors: Error: data must be a data frame, or other object coercible by fortify(), not a character vector

library(ggplot2)
library(scales)

ggplot(data = math_and_portuguese, aes(x = G3.x)) +
    geom_bar(aes(y = (..count..)/sum(..count..)), position = "dodge", fill = "cornflowerblue", color="black") +
    geom_text(aes(y = round((..count..)/sum(..count..),2),
                  label=paste0(round(prop.table(..count..) * 100, 2), '%'),
                  size = 3, hjust = 0.5, vjust = -1, position = "stack"),
              stat = 'count',
              position = position_dodge(.9),
              size = 3)+
    labs(x = 'G3 Mathematics grade', y = 'Percent')
p1

Answer 1

The ordering of any discrete item is done in the following way:

• if your column is a factor, ggplot2 orders by the levels of the factor
• if your column is not a factor, ggplot2 orders alphanumerically

In this case, the solution is to set the levels of math_and_portuguese$G3.x discretely by converting to a factor and specifying the levels you want:

math_and_portuguese$G3.x <- factor(math_and_portuguese$G3.x,
  levels=c("Excellent", "Very Good", "Good", "Sufficient", "Weak", "Poor"))

Run that first, then the ordering of your axis should reflect the levels of the factor.