R geom_tile on theme_void has blank space above and below plot

Question

When using geom_tile() to make a ggplot object with theme_void() there are blank areas at top and bottom of plot, and when using patchwork to add pieces these cause a mis-alignment of right=side marginal bars (as in screenshot attached).

Please is there a way to eliminate the blank spaces? I tried a custom theme (code further below) but it didnt help (and sometimes put space on left/right sides also)

library(tidyverse)
library(grid)
library(patchwork)

long <- dget('long.txt')

# Summarise data for marginal plots
in_y_df <- long %>% 
  group_by(in_y) %>% 
  summarise(value = sum(value)) %>% 
  mutate(value = value / sum(value)) %>% 
  mutate(str = paste0( round(value * 100, digits=0), '%' ))

out_x_df <- long %>% 
  group_by(out_x) %>% 
  summarise(value = sum(value)) %>% 
  mutate(value = value / sum(value)) %>% 
  mutate(str = paste0( round(value * 100, digits=0), '%' ))

# Marginal plots
py <- ggplot(in_y_df, aes(value, in_y)) +
  geom_col(width = .7, fill = 'gray64') +
  geom_text(aes(label = str), hjust = -0.1, size = 10 / .pt) +
  scale_x_continuous(expand = expansion(mult = c(.0, .25))) +
  theme_void() +
  theme(plot.margin = unit(c(0,0,0,0), "mm"))

px <- ggplot(out_x_df, aes(out_x, value)) +
  geom_col(width = .7, fill = 'gray8') +
  geom_text(aes(label = str), vjust = -0.5, size = 10 / .pt) +
  scale_y_continuous(expand = expansion(mult = c(.0, .25))) +
  theme_void() +
  theme(plot.margin = unit(c(0,0,0,0), "mm"))

h2 <- ggplot(long, aes(out_x, in_y, fill = value)) +
  geom_tile(color = 'black', size = 0.2) +
  coord_equal() +
  geom_text(aes(label = value), size = 12 / .pt) +
  scale_fill_gradient(low = "#E9F6E5", high = "#84CB83") +
  theme_void() +
  theme(legend.position = 0) +
  labs(x = NULL, y = NULL, fill = NULL)

heatmap_minus_axisText <- h2

# Version with axis labels not in heatplot
yLabelsPlot <- plot_spacer()
xLabelsPlot <- plot_spacer()

squarePlot <- plot_spacer() + px + plot_spacer() + 
  yLabelsPlot + heatmap_minus_axisText + py +
  plot_spacer() + xLabelsPlot + plot_spacer() +
  plot_layout(ncol = 3, widths = c(1, 2, 1.4), heights = c(1.2, 2, 1.3))
squarePlot

The axis labels (not yet made) will be done separately because when included in heatmap object they cause top-bars to misalign after stitching with patchwork, as shown in 2nd picture.

heatPlot <- plot_spacer() + px + plot_spacer() + 
  plot_spacer() + ph + py + 
  plot_layout(ncol = 3, widths = c(1, 2, 0.8), heights = c(1.2, 2))

Here is the file for dget() to make fake dataframe:

structure(list(in_y = structure(c(4L, 3L, 6L, 2L, 1L, 5L, 4L, 
3L, 6L, 2L, 1L, 5L, 4L, 3L, 6L, 2L, 1L, 5L, 4L, 3L, 6L, 2L, 1L, 
5L, 4L, 3L, 6L, 2L, 1L, 5L, 4L, 3L, 6L, 2L, 1L, 5L, 4L, 3L, 6L, 
2L, 1L, 5L), .Label = c("R5BnqKkCI3iHHfBDOd3D", "pJoPxfMkRaLbl2ESDD3s", 
"8vXGhUVjAubzkubDQft5", "rtUdC7ZmBc8GfiyyJ9DF", "teSB1z4wpHzLLmqwLR4t", 
"55G18mbzeqajtzO7WLLM"), class = "factor"), out_x = structure(c(1L, 
1L, 1L, 1L, 1L, 1L, 4L, 4L, 4L, 4L, 4L, 4L, 6L, 6L, 6L, 6L, 6L, 
6L, 3L, 3L, 3L, 3L, 3L, 3L, 2L, 2L, 2L, 2L, 2L, 2L, 5L, 5L, 5L, 
5L, 5L, 5L, 7L, 7L, 7L, 7L, 7L, 7L), .Label = c("MCbgrg3f1oVlszlUUddq", 
"yjqUPElzDhsAHKpVPLo6", "j3tZCBrw6qY9X2pYDc9Y", "iW2TVkR3NawpBC8p59F2", 
"L1Ai51LaakWu0b47zypc", "HjkPWE5auDZ0dOH3G1L1", "WEfxf3XV0CMSWRRLHheY"
), class = "factor"), value = c(2L, 1L, 1L, 1L, 4L, 4L, 0L, 0L, 
0L, 0L, 1L, 1L, 2L, 0L, 0L, 0L, 1L, 2L, 1L, 1L, 0L, 1L, 0L, 0L, 
3L, 0L, 0L, 0L, 1L, 1L, 2L, 0L, 1L, 0L, 2L, 1L, 1L, 0L, 0L, 0L, 
1L, 0L)), row.names = c(NA, -42L), class = "data.frame")

custom theme

heatmap_theme <-  theme(
      axis.title.x = element_blank(),
      axis.title.y = element_blank(),
      axis.ticks.x = element_blank(),
      axis.ticks.y = element_blank(),
      axis.ticks.length = unit(0, "pt"),
      legend.position = "none",
      panel.grid.major = element_blank(),
      panel.grid.minor = element_blank(),
      panel.background = element_blank(),
      plot.margin = unit(c(0,0,0,0), "mm"),
      panel.spacing = unit(c(0,0,0,0), "mm")
    )

Answer 1

You could try to specify axis limits and suppress automatic axis expansion. Setting axis limits is more straightforward for factors: if needed, convert numeric tile coordinates to character (as.character) or factor (as.factor). Also remove the legend.

Example of stripped heatmap:

data.frame(
    x = c('col_1','col_2','col_1','col_2'),
    y = c('row_1','row_1','row_2','row_2'),
    value = runif(4)
) %>%
    ggplot() +
    geom_tile(aes(x, y, fill = value)) +
    scale_x_discrete(limits = c('col_1','col_2'), expand = c(0,0)) +
    scale_y_discrete(limits = c('row_1','row_2'), expand = c(0,0)) +
    scale_fill_continuous(guide = 'none') +
    theme_void()

edit: for composite charts, there's also cowplot