GGPlot Axis Limits and Scales

Key ggplot2 R functions

Start by creating a scatter plot using the cars data set:

library(ggplot2)
p <- ggplot(cars, aes(x = speed, y = dist)) + 
  geom_point()

3 Key functions are available to set the axis limits and scales:

1. Without clipping (preferred). Cartesian coordinates. The Cartesian coordinate system is the most common type of coordinate system. It will zoom the plot, without clipping the data.

p + coord_cartesian(xlim = c(5, 20), ylim = c(0, 50))

2. With clipping the data (removes unseen data points). Observations not in this range will be dropped completely and not passed to any other layers.

# Use this
p + scale_x_continuous(limits = c(5, 20)) + 
  scale_y_continuous(limits = c(0, 50))

# Or this shothand functions
p + xlim(5, 20) + ylim(0, 50)

3. Expand the plot limits to ensure that a given value is included in all panels or all plots.

# set the intercept of x and y axes at (0,0)
p + expand_limits(x = 0, y = 0)

# Expand plot limits
p + expand_limits(x = c(5, 50), y = c(0, 150))

Change axis limits

# Default plot
print(p)

# Change axis limits using coord_cartesian()
p + coord_cartesian(xlim =c(5, 20), ylim = c(0, 50))

p + xlim(5, 20) + ylim(0, 50)

p + scale_x_continuous(name = "Speed of cars", limits = c(0, 30)) +
  scale_y_continuous(name = "Stopping distance", limits = c(0, 150))

Expand plot limits

Key function expand_limits(). Can be used to :

• quickly set the intercept of x and y axes at (0,0)
• expand the limits of x and y axes

# set the intercept of x and y axis at (0,0)
p + expand_limits(x = 0, y = 0)

# change the axis limits
p + expand_limits(x=c(0,30), y=c(0, 150))

Conclusion

• Create an example of ggplot:

library(ggplot2)
p <- ggplot(cars, aes(x = speed, y = dist)) + 
  geom_point()

• Set a ggplot axis limits:

p + coord_cartesian(xlim = c(5, 20), ylim = (0, 50))

• Set the intercept of x and y axis at zero (0, 0) coordinates:

p + expand_limits(x = 0, y = 0)