ggplot discrete x axis labels code example
Example: change label x axis ggplot2
theme(
axis.title = element_text(), # Change both x and y axis titles
axis.title.x = element_text(), # Change x axis title only
axis.title.x.top = element_text(), # For x axis label on top axis
axis.title.y = element_text(), # Change y axis title only
axis.title.y.right = element_text(), # For y axis label on right axis
)