Top and Bottom plots seem to have less spacing when using `subplot` in `plotly`

首先运行提供的 R reprex，其中包含 subplot 和 45 个直方图，以复现顶行和底行之间的间距问题。跟踪 subplot 的布局行为，并验证生成的直方图具有相等的边距且标签可见；当顶部和底部的图以一致的间距排列时，问题即得到解决。

Description:

When attempting to display multiple histograms using subplot from the plotly package, the plots in the top row and bottom row appear with less spacing, making them difficult to analyze. This issue is primarily reproducible when there are large number of visualizations to plot together.

Here is a minimal reprex for the same:

# Load necessary libraries
library(ggplot2)
library(plotly)

# set seed for reproducibility
set.seed(123)

# simulate a dataset
simulateDataset <- function(numRows = 100, numCols = 40) {
  data <- data.frame(matrix(nrow = numRows, ncol = numCols))
  
  for (i in 1:numCols) {
    if (i %% 2 == 0) {
      data[[i]] <- rnorm(numRows, mean = 50, sd = 10)  # Normal distribution
    } else {
      data[[i]] <- rexp(numRows, rate = 0.1)           # Exponential distribution
    }
  }
  
  names(data) <- paste0("Var", 1:numCols)
  return(data)
}

# simulate the data
df <- simulateDataset(numRows = 100, numCols = 45)

# create histograms and convert to plotly
plotList <- lapply(names(df), function(colName) {
  if (is.numeric(df[[colName]])) {
    p <- ggplot(df, aes(x = .data[[colName]])) + 
      geom_histogram(binwidth = 0.5, fill = 'grey', color = 'black')
    
    ggplotly(p)
  }
})

# define number of rows based on number of plots in each row
numberOfRows <- ceiling(length(plotList) / 3)

# display all plots together using subplot
subplot(plotList, nrows = numberOfRows, margin = 0.05, titleX = TRUE, titleY = TRUE)

Expected Behavior:
Each histogram should have equal margins, with appropriate spacing and labels visible.

Screenshots