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

Comienza ejecutando el reprex de R proporcionado con subplot y 45 histogramas para reproducir el problema de espaciado entre las filas superior e inferior. Rastrea el comportamiento del diseño de subplot y verifica que los histogramas resultantes tengan márgenes iguales con etiquetas visibles; el problema se resuelve cuando los gráficos superiores e inferiores tienen un espaciado uniforme.

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