How to arrange three ggplot2 plots with the same size - r

Question

I have 3 plot that I want to arrange in 2 rows, 1 column, and all present the same size.
My problem is that the 3rd (row 2) plot present legend that is common to all plots, and it make just a little bit small that the rest.
library(phyloseq)
library(vegan)
library(ggplot2)
library(ggpubr)
data("GlobalPatterns")
GP <- GlobalPatterns
GP.ord <- ordinate(GP, "NMDS", "bray", k=3)
DF_ord <- plot_ordination(GP, GP.ord, axes=c(1:3), justDF = TRUE)
head(DF_ord)
NMDS1 NMDS2 NMDS3 X.SampleID Primer Final_Barcode Barcode_truncated_plus_T Barcode_full_length SampleType
CL3 -0.2128261 0.7818086 -1.12967604 CL3 ILBC_01 AACGCA TGCGTT CTAGCGTGCGT Soil
CC1 -0.5826017 0.7847393 -0.83925680 CC1 ILBC_02 AACTCG CGAGTT CATCGACGAGT Soil
SV1 -0.4011154 1.1073660 -0.90078134 SV1 ILBC_03 AACTGT ACAGTT GTACGCACAGT Soil
M31Fcsw 2.2390139 -0.1076734 0.03626119 M31Fcsw ILBC_04 AAGAGA TCTCTT TCGACATCTCT Feces
M11Fcsw 2.1733638 -0.2290418 0.33818019 M11Fcsw ILBC_05 AAGCTG CAGCTT CGACTGCAGCT Feces
M31Plmr 0.1611431 1.3583510 0.67498162 M31Plmr ILBC_07 AATCGT ACGATT CGAGTCACGAT Skin
Generate the plots
Plot1
p1 <- ggplot(DF_ord, aes(x = NMDS1, y = NMDS2)) +
geom_vline(xintercept = 0, linetype="dashed", size = 0.5, color= "#999999") +
geom_hline(yintercept = 0, linetype="dashed", size = 0.5, color= "#999999") +
geom_point( aes(colour= SampleType), size = 3.5, alpha=0.7) +
theme_bw() +
theme(panel.grid.major = element_blank(), panel.grid.minor = element_blank())
Plot2
p2 <- ggplot(DF_ord, aes(x = NMDS1, y = NMDS3)) +
geom_vline(xintercept = 0, linetype="dashed", size = 0.5, color= "#999999") +
geom_hline(yintercept = 0, linetype="dashed", size = 0.5, color= "#999999") +
geom_point( aes(colour= SampleType), size = 3.5, alpha=0.7) +
theme_bw() +
theme(panel.grid.major = element_blank(), panel.grid.minor = element_blank())
Plot3
p3 <- ggplot(DF_ord, aes(x = NMDS2, y = NMDS3)) +
geom_vline(xintercept = 0, linetype="dashed", size = 0.5, color= "#999999") +
geom_hline(yintercept = 0, linetype="dashed", size = 0.5, color= "#999999") +
geom_point( aes(colour= SampleType), size = 3.5, alpha=0.7) +
theme_bw() +
theme(panel.grid.major = element_blank(), panel.grid.minor = element_blank())
Eliminate the legend for p1 and p2
p1 <- p1 + theme(legend.position = "none")
p2 <- p2 + theme(legend.position = "none")
Arrange the 3 plots
top_row = ggarrange(p1, p2, ncol = 2, labels = c("A)", "B)"))
bottom_row = ggarrange(NULL, p3, NULL, ncol = 3, labels = c("", "C)", ""), widths = c(1,2,1))
myplot <- ggarrange(top_row, bottom_row, ncol = 1)
The top_row plots are little bit bigger (rectangle) than the bottom_row plot (square) !!
myplot
How to make all plots with the same size (square), and keep the legend common to all in the botton_row plot ?

Answer 1

A possible solution would be to "fake a legend" like in this example:
p1 <- iris |>
ggplot2::ggplot(
mapping = ggplot2::aes(
x = Sepal.Length,
y = Sepal.Width,
color = Species
)
) +
ggplot2::geom_point() +
ggplot2::theme_minimal() +
ggplot2::theme(legend.position = "none")
p4 <- iris |>
dplyr::count(Species) |> # no overplotting
ggplot2::ggplot(
mapping = ggplot2::aes(
x = 0,
y = Species,
color = Species,
label = Species
)
) +
ggplot2::geom_point() +
ggplot2::theme_void() +
ggplot2::geom_text(x = 0.1,
color = "#000000", hjust = "left") +
ggplot2::theme(legend.position = "none") +
ggplot2::xlim(-1,1)
lay <- rbind(
c(1,2),
c(3,4)
)
gridExtra::grid.arrange(
p1,
p1,
p1,
p4,
layout_matrix = lay
)