如何在R的plot.regsubsets中自定义Y轴小数位数？

Quickest Fix: Redraw the Y-axis Manually #

If you just need to tweak the decimal places for a single plot, you don’t have to dig into the function’s source code. Here’s a straightforward workaround:

1. Run your plot.regsubsets() call with yaxt="n" to skip the default Y-axis rendering:

   library(leaps)
   # Example regression model
   regfit <- regsubsets(mpg ~ ., data = mtcars)
   # Generate the plot without the default Y-axis
   plot(regfit, yaxt = "n")
   

2. Redraw the Y-axis with your preferred number of decimal places using axis(). For example, to show 3 decimal places:

   # Grab the default tick positions
   y_ticks <- axTicks(2)
   # Redraw the axis with custom formatted labels
   axis(2, at = y_ticks, labels = sprintf("%.3f", y_ticks), las = 2)
   

   Adjust the format string to match your needs: use %.1f for 1 decimal place, %.4f for 4, etc.

Permanent Fix: Modify the Function to Add a Decimal Place Parameter #

Since you spotted the hardcoded %.2f in line 33 of the function, we can create a custom version of plot.regsubsets() that lets you pass a decimal place parameter directly. Here’s how:

1. Fetch the full source code of the function by running getS3method("plot", "regsubsets") in your console. Copy all the code into your script.
2. Rename the function (e.g., plot.regsubsets_custom) to avoid overwriting the original, then add a digits.y parameter to the function definition (set a default of 2 to match the original behavior).
3. Find the line where the Y-axis labels are generated (the one with sprintf("%.2f", yval)), and replace the hardcoded 2 with our new parameter. We’ll build the format string dynamically using paste0():

   # Modified function snippet (use the full source you copied)
   plot.regsubsets_custom <- function (x, labels = obj$xnames, main = NULL, scale = c("bic", 
       "Cp", "adjr2", "r2"), col = gray(seq(0, 0.9, length = 10)), 
       digits.y = 2, # New parameter added here
       ...) {
       # ... rest of original code ...
       # Updated sprintf line to use digits.y
       axis(2, at = yval, labels = sprintf(paste0("%.", digits.y, "f"), yval), las = 2)
       # ... rest of original code ...
   }
   

4. Now you can use this custom function and specify decimal places whenever you need:

   # Plot with 3 decimal places on Y-axis
   plot.regsubsets_custom(regfit, digits.y = 3)
   # Plot with 1 decimal place
   plot.regsubsets_custom(regfit, digits.y = 1)
   

内容的提问来源于stack exchange，提问作者gosuto