Understanding the Problem

When creating a figure with multiple subplots using base R, we often encounter issues where certain elements (like axis boxes) are lost or obscured due to other plotting commands. In this blog post, we will delve into the world of base R plotting and explore how to keep axis boxes visible across different subplots.

The Issue

The problem at hand is that when using par(xpd=F) before plotting functions, it affects all subsequent plotting commands, including those used for text annotations. This can lead to unintended consequences where bottom row graphs appear to be “overdrawing” the top row ones due to shared axis settings.

A Closer Look

Upon examining the answer provided, we notice that setting xpd=NA within individual text annotation functions prevents this global x-axis positioning issue from impacting our plots. This adjustment ensures that only the desired text element is positioned correctly on its respective subplot, avoiding unwanted overlap or alteration of axis elements.

The Solution

To solve the problem and maintain visible axis boxes across all subplots in a multi-row figure:

1. Adjust xpd for individual text annotations: As mentioned in the answer, adding xpd=NA to each text() function call prevents the global x-axis positioning issue from affecting your plots.
2. Utilize box() and other plotting elements judiciously: Carefully apply box() and similar functions only where needed to avoid interference with other subplot elements.

Here’s an example of how you might implement these steps:

# Create a new figure with multiple subplots in a grid layout
library(biwavelet)
par(mfrow=c(2, 2), xpd=F) # Apply the adjustment for each plot individually

# Generate some data (replace this as needed)
dat <- seq(1, 500)

# Plot the top-left subplot
plot(wt(dat),
     xaxt = 'n',
     xlab = "",
     cex.axis = 1.5,
     cex.lab = 1.5)
axis(1, at = seq(0, 500, by = 100), cex.axis = 1.5, col.axis = 'NA')
mtext("Variable 1", side = 3, cex = 1.5, line = 0.1)

# Plot the top-right subplot
plot(wt(dat),
     xaxt = 'n',
     col.axis = 'NA',
     xlab = "",
     ylab = "")
axis(1, at = seq(100, 500, by = 100), cex.axis = 0.1, col.axis = 'NA')
mtext("Variable 2", side = 3, cex = 1.5, line = 0.1)

# Plot the bottom-left subplot
plot(wt(dat),
     xaxt = 'n',
     cex.axis = 1.5,
     ylab = "")
axis(1, at = seq(100, 500, by = 100), cex.axis = 1.5)
mtext("Variable 3", side = 3, cex = 1.5, line = 0.1)

# Plot the bottom-right subplot
plot(wt(dat),
     xaxt = 'n',
     col.axis = 'NA',
     ylab = "",
     xlab = "")
axis(1, at = seq(100, 500, by = 100), cex.axis = 0.1)
mtext("Variable 4", side = 3, cex = 1.5, line = 0.1)

# Add text annotations with individual x-axis positioning
text("Location A", x = 250, y = 200, srt = 270, cex = 1.2)
box(lty = "solid", col = 'black')

text("Location B", x = 250, y = 300, srt = 270, cex = 1.2, xpd=NA)
box(lty = "solid", col = 'black')

By following these steps and making the necessary adjustments to your plotting commands, you should be able to keep axis boxes visible across different subplots in a multi-row figure.

Final Thoughts

Base R offers many powerful tools for creating complex figures, but it can also pose challenges when working with multiple subplots. By understanding how xpd works and making strategic adjustments, you can effectively control the positioning of elements within your plots to achieve your desired visual outcome.

Last modified on 2023-11-23