Add an Arrow Layer to an ordiggplot Graph.

Function adds layers of arrows (ggplot2::geom_segment()) and (optionally) their text labels (ggplot2::geom_text() or ggplot2::geom_label()) to an ordiggplot() graph. Typically these arrows are biplot or regression scores, but the function allows drawing species arrows for PCA biplots, or adding fitted environmental vectors of vegan::envfit().

Usage

geom_ordi_arrow(
  score,
  data,
  text = TRUE,
  box = FALSE,
  arrow.mul = 1,
  arrow.params = list(),
  text.params = list(),
  ...
)

Arguments

score

Ordination score to be added to the plot.

data

Alternative data to the function that will be used instead of score. This can be a vegan::envfit result object which is used to draw arrows of fitted vectors.

text

Add text labels to the plot (logical).

box

Draw a non-transparent box behind the text (logical).

arrow.mul

Arrow multiplier when arrows end points are given in data. Ignored for biplot and regression scores or species scores which are already scaled in constrained ordination methods when calling ordiggplot().

arrow.params, text.params

Parameters to modify arrows or their text labels.

...

other arguments passed to ggplot2::geom_segment(), ggplot2::geom_label() and ggplot2::geom_text()

Value

Returns ggplot2 layers geom_segment for arrows, and geom_text or geom_label (optionally) for their names.

See also

Underlying functions are ggplot2::geom_segment(), ggplot2::geom_text() and ggplot2::geom_label().

Author

Jari Oksanen

Examples

library(vegan)
data(varespec, varechem, package="vegan")
## PCA biplot
mod <- rda(varespec)
ordiggplot(mod, scaling = "sites", corr = TRUE) +
  geom_ordi_axis() +
  geom_ordi_point("sites") +
  geom_ordi_arrow("species")

## RDA
mod <- rda(varespec ~ N + K + Al + Baresoil, varechem)
ordiggplot(mod) +
  geom_ordi_axis() +
  geom_ordi_point("sites") +
  geom_ordi_arrow("biplot", box = TRUE)