tidy vegan procrustes errors plot for ggplot2

tidy_procrustes_ggplot2.R

library(vegan)
library(tidyverse)
data(varespec)
vare.dist <- vegdist(wisconsin(varespec))
mds.null <- monoMDS(vare.dist, y = cmdscale(vare.dist))
mds.alt <- monoMDS(vare.dist)
x <- protest(mds.alt, mds.null)


rot <- x$rotation
tails <- tibble(X_IN = x$Yrot[, 1], Y_IN = x$Yrot[, 2])
heads <- tibble(X_OUT = x$X[, 1], Y_OUT = x$X[, 2])
tab <- bind_cols(tails, heads)

ggplot(tab) +
  geom_hline(aes(yintercept = 0), color = "grey70", size = 0.5) +
  geom_vline(aes(xintercept = 0), color = "grey70", size = 0.5) +
  geom_abline(aes(slope = rot[1,2]/rot[1,1], intercept = 0), linetype = "dashed", color = "grey70", size = 0.5) +
  geom_abline(aes(slope = rot[2,2]/rot[2,1], intercept = 0), linetype = "dashed", color = "grey70", size = 0.5) +
  geom_point(aes(x = X_IN, y = Y_IN)) +
  geom_segment(aes(x = X_IN, y = Y_IN, xend = X_OUT, yend = Y_OUT), arrow = arrow(angle = 20, length = unit(0.02, "npc"), type = "closed")) +
  xlab("Dimension 1") +
  ylab("Dimension 2") +
  labs(title = " Procrustes errors") +
  theme_minimal()