To add **x-axis **and **y-axis** labels in **ggplot2**, you can use the following methods:

Using **xlab **and **ylab **Functions:

library("Sleuth2")

library("ggplot2")

ggplot(ex1221, aes(Density, Discharge)) +

geom_point(aes(size=NO3)) +

scale_size_area() +

xlab("X-label") +

ylab("Y-label") +

ggtitle("Weighted Scatterplot of Density (people/km^

2) vs. Discharge and Nitrogen Levels (PPM)")

Using **scale_x_continuous** and **scale_y_continuous**:

ggplot(ex1221, aes(Density, Discharge)) +

geom_point(aes(size=NO3)) +

scale_size_area() +

scale_x_continuous("X-label") +

scale_y_continuous("Y-label") +

ggtitle("Weighted Scatterplot of Density (people/km^

2) vs. Discharge and Nitrogen Levels (PPM)")

Using **labs **Function:

ggplot(ex1221, aes(Density, Discharge)) +

geom_point(aes(size=NO3)) +

scale_size_area() +

labs(size= "Nitrogen",

x = "X-label",

y = "Y-label",

title = "Weighted Scatterplot of Density (people/km^

2) vs. Discharge and Nitrogen Levels (PPM)")

Output: