How to change font size of text and axes on R plots

How to Change Font Size of Text and Axes on R Plots

R provides multiple ways to customize the font size of text and axes in plots, enabling users to improve plot readability and presentation. Here’s how you can adjust these settings:

1. Using cex Parameter

The cex parameter controls the size of text elements relative to the default size.

• cex.main: Adjusts the title size.
  
• cex.lab: Adjusts the axis label size.
  
• cex.axis: Adjusts the tick mark label size.
  
• cex.sub: Adjusts the subtitle size.
  

Example:

plot(1:10, main = "Main Title", xlab = "X-axis", ylab = "Y-axis",
     cex.main = 1.5, cex.lab = 1.2, cex.axis = 1, cex.sub = 0.8)

2. Using par() Function

The par() function can set graphical parameters globally before creating a plot.

par(cex.main = 1.5, cex.lab = 1.2, cex.axis = 1)
plot(1:10, main = "Main Title", xlab = "X-axis", ylab = "Y-axis")

3. Customizing Font Size with ggplot2

For ggplot2 users, font sizes can be customized using the theme() function.

Example:

library(ggplot2)
ggplot(mtcars, aes(x = wt, y = mpg)) +
  geom_point() +
  labs(title = "Title", x = "X-axis", y = "Y-axis") +
  theme(plot.title = element_text(size = 16),
        axis.title = element_text(size = 14),
        axis.text = element_text(size = 12))

4. Using text() for Custom Text

To add custom text elements to a plot, use text() with the cex parameter.

  plot(1:10)text(5, 8, "Custom Text", cex = 2)

Key Takeaways

• Use cex for base R plots and theme() for ggplot2 to adjust font sizes.
  
• par() can set global font size preferences in base R.
  

Customize sizes for individual plot elements (title, axis labels, tick marks) for precise control.

To adjust the font size of text and axes on R plots, you can use various functions and parameters within the base R graphics system or through packages like ggplot2. Here's how you can do it using both methods:

Base R Graphics:

You can use the par() function to set graphical parameters, including font sizes. Here's an example:

# Set up example data
x <- 1:10
y <- 1:10
# Create a plotplot(x, y, main = "Scatter Plot", xlab = "X-axis", ylab = "Y-axis")# Adjust font size of title, x-axis label, and y-axis labelpar(cex.main = 2, cex.lab = 1.5)

In this example, cex.main controls the size of the main title, and cex.lab controls the size of the axis labels.

ggplot2:

With ggplot2, you can adjust font sizes using the theme() function. Here's an example:

  library(ggplot2)# Set up example datadf <- data.frame(x = 1:10, y = 1:10)# Create a ggplot objectp <- ggplot(df, aes(x, y)) +  geom_point() +  labs(title = "Scatter Plot", x = "X-axis", y = "Y-axis")# Adjust font size of title, x-axis label, and y-axis labelp + theme(  plot.title = element_text(size = 16),  axis.title.x = element_text(size = 14),  axis.title.y = element_text(size = 14))

In this example, size within element_text() controls the font size of the plot title and axis labels.

Feel free to adjust the font size values (cex.main, cex.lab, size) according to your preferences. These are just examples to demonstrate how to change font sizes on R plots using both base R graphics and ggplot2.