Remove x-labels from the last plot in ggplot

Question

I have written the following code to show four plots

Scores <- as.factor(sampleXYPCA$PC1)
p1 <- ggplot(sampleXYPCA, aes(x = X_UTM_, y = Y_UTM_, color=PC1)) + 
  geom_point( ) + scale_color_gradient(low="blue", high="red") +
  geom_polygon(data = xy, aes(x = xBounds, y = yBounds), 
  color="orange", alpha = 0.2, show.legend = FALSE) + labs( x ="x (m) ", y = "y (m)") +
  theme(axis.text.x=element_blank(),axis.text.y=element_blank(), 
        axis.ticks.x=element_blank(),axis.ticks.y=element_blank(),
        legend.position="right", legend.direction="vertical") 
  
Scores <- as.factor(sampleXYPCA$PC2)
p2 <- ggplot(sampleXYPCA, aes(x = X_UTM_, y = Y_UTM_, color=PC2)) + 
  geom_point( ) + scale_color_gradient(low="blue", high="red") +
  geom_polygon(data = xy, aes(x = xBounds, y = yBounds), 
  color="orange", alpha = 0.2, show.legend = FALSE) + labs( x ="x (m) ", y = "y (m)") +
  theme(axis.text.x=element_blank(),axis.text.y=element_blank(), 
        axis.ticks.x=element_blank(),axis.ticks.y=element_blank()) 

Scores <- as.factor(sampleXYPCA$PC3)
p3 <- ggplot(sampleXYPCA, aes(x = X_UTM_, y = Y_UTM_, color=PC3)) + 
  geom_point( ) + scale_color_gradient(low="blue", high="red") +
  geom_polygon(data = xy, aes(x = xBounds, y = yBounds), 
  color="orange", alpha = 0.2, show.legend = FALSE) + labs( x ="x (m) ", y = "y (m)") +
  theme(axis.text.x=element_blank(),axis.text.y=element_blank(), 
        axis.ticks.x=element_blank(),axis.ticks.y=element_blank()) 

Scores <- as.factor(sampleXYPCA$PC4)
p4 <- ggplot(sampleXYPCA, aes(x = X_UTM_, y = Y_UTM_, color=PC4)) + 
  geom_point( ) + scale_color_gradient(low="blue", high="red") +
  geom_polygon(data = xy, aes(x = xBounds, y = yBounds), 
  color="orange", alpha = 0.2, show.legend = FALSE) + labs( x ="x (m) ", y = "y (m)") +
  theme(axis.text.x=element_blank(),axis.text.y=element_blank(), 
        axis.ticks.x=element_blank(),axis.ticks.y=element_blank()) 

figure <- ggarrange(p1, p2,p3,p4 + font("x.text", size = 10),
                    ncol = 2, nrow = 2)
show(figure)

I have two issues that I am trying to fix:

1. I want to remove the values at x-axis at the last plot (PC4), as in the previous plots.
2. I want to set the same scale at the colour bar for all plots (from -3,3)

For convenience, I copy the first lines of the dataframe (sampleXYPCA) that I am using:

     X_UTM_  Y_UTM_         PC1          PC2         PC3         PC4
1   6501395 1885718 -1.37289727  2.320717816  0.93434761  1.24571643
2   6500888 1885073 -1.22111900  4.021127182  1.89434320  1.26801802
3   6500939 1885241 -0.58212873  3.301443355 -1.79458946  0.63329006
4   6500965 1884644 -1.13872381  4.521231473  2.43925215  0.53962882
5   6501608 1884654 -0.24075643  5.871225725  0.69257238  0.89294843
6   6501407 1883939 -0.15938861  3.965081981  1.40970861 -0.77825417
7   6501581 1883630 -0.59187192  2.904278269  0.40655574 -1.66513966

Answer 1

Using facet_wrap and adding an aerial basemap for visualisation (personal prefence when plotting spatial data):

#sample data as dput
dt <- structure(list(x = c(6501395, 6500888, 6500939, 6500965, 6501608, 
6501407, 6501581), y = c(1885718, 1885073, 1885241, 1884644, 
1884654, 1883939, 1883630), pca1 = c(-1.37289727, -1.221119, 
-0.58212873, -1.13872381, -0.24075643, -0.15938861, -0.59187192
), pca2 = c(2.320717816, 4.021127182, 3.301443355, 4.521231473, 
5.871225725, 3.965081981, 2.904278269), pca3 = c(0.93434761, 
1.8943432, -1.79458946, 2.43925215, 0.69257238, 1.40970861, 0.40655574
), pca4 = c(1.24571643, 1.26801802, 0.63329006, 0.53962882, 0.89294843, 
-0.77825417, -1.66513966)), class = "data.frame", row.names = c(NA, 
-7L))

#load libraries
library(sf)
library(tidyr)
library(ggplot2)
library(ggspatial)
library(tmaptools)

#pivot_longer on PCA
dt <- pivot_longer(dt, cols = c("pca1", "pca2", "pca3", "pca4"), names_to = "PCA", values_to = "Score")

#convert to sf object (assumed that you use espg:32629, change to whatever you use as the coordinate system)
dt <- st_as_sf(dt, coords = c("x", "y"), crs = st_crs(32629))

#load a basemap
basemap <- read_osm(dt, type = "https://mt1.google.com/vt/lyrs=y&x={x}&y={y}&z={z}", zoom = 15, ext = 1.2)

#plot
ggplot() + layer_spatial(basemap) + geom_sf(data = dt, aes(col = Score), size = 3) + facet_wrap(~PCA) + labs( x ="x (m) ", y = "y (m)") +
  theme_bw() + theme(axis.text.x=element_blank(),axis.text.y=element_blank(), 
  axis.ticks.x=element_blank(),axis.ticks.y=element_blank()) +
  scale_x_continuous(expand = c(0.01,0.01)) +
  scale_y_continuous(expand = c(0.01,0.01)) +
  scale_color_gradient(low="blue", high="red")

Answer 2

Using some dummy data to illustrate a possible solution, this may help.

The issue in the OP's question seems to be with the call to ggarrange. Check out the documentation with ?ggarrange

library(ggpubr)
library(ggplot2)


p1 <- 
  ggplot(mtcars, aes(mpg, wt))+
  geom_point() +
  theme(axis.text.x=element_blank(),axis.text.y=element_blank(), 
        axis.ticks.x=element_blank(),axis.ticks.y=element_blank())

figure <- 
  ggarrange(p1, p1, p1, p1, 
            font.label = list(size = 10),
            ncol = 2,
            nrow = 2)

show(figure)

^{Created on 2021-12-10 by the reprex package (v2.0.1)}