ord_plot-label-helpers: Helpers for ord_plot label adjustments

In david-barnett/microViz: Microbiome Data Analysis and Visualization

Helpers for ord_plot label adjustments

Description

Consider moving these functions to tax_lab_style() man page/.R file.

See functions section.

Usage

textAngleCalc(xvec, yvec, max = 90, ratio = 1, perpendicular = FALSE)

textHjustCalc(xvec, adjust = TRUE)

Arguments

xvec	numeric vector of values used for x axis
yvec	numeric vector of values used for y axis
max	maximum absolute numeric value of angle in degrees to return (for rotating text/labels)
ratio	adjustment for aspect ratio of plot when setting a fixed coordinate aspect ratio with coord_fixed (advised)
adjust	logical, apply hjust or not (FALSE means return only 0.5)

Value

numeric vector representing either angles to rotate geom_text labels, or hjust values

Functions

• textAngleCalc(): Calculate rotation of text labels for ordination plot

• textHjustCalc(): Calculate hjust of text labels for ordination plot

Examples

library(ggplot2)
library(dplyr)

# create basic ggplot for labelling

df <- mtcars %>% mutate(across(everything(), scale))

p <- ggplot(df, aes(mpg, hp, label = rownames(df))) +
  geom_segment(xend = 0, yend = 0, color = "lightgrey") +
  annotate(x = 0, y = 0, geom = "point", size = 4) +
  theme_minimal()

p

# calculate new variable within aes mapping non-standard evaluation
p +
  geom_text(size = 2.5, mapping = aes(angle = textAngleCalc(mpg, hp))) +
  coord_fixed(ratio = 1)

# equivalent: calculate variable outside aes by referring to dataframe again
p +
  geom_text(size = 2.5, angle = textAngleCalc(df$mpg, df$hp)) +
  coord_fixed(ratio = 1)

# fixing aspect ratio is important
# see how angles may be incorrect otherwise
p +
  geom_text(size = 2.5, mapping = aes(angle = textAngleCalc(mpg, hp)))

# ratio argument allows matching angles with alternative aspect ratio
p +
  geom_text(size = 2.5, angle = textAngleCalc(df$mpg, df$hp, ratio = .5)) +
  coord_fixed(ratio = .5)

p +
  geom_text(size = 2.5, angle = textAngleCalc(df$mpg, df$hp, ratio = 1.5)) +
  coord_fixed(ratio = 1.5)

# perpendicular argument makes text perpendicular instead of parallel
p +
  geom_text(
    check_overlap = TRUE, size = 2.5,
    angle = textAngleCalc(df$mpg, df$hp, perpendicular = TRUE, ratio = 1.5)
  ) +
  coord_fixed(ratio = 1.5, clip = "off")

# max angle limits extreme text angles
p +
  geom_text(
    size = 2.5, check_overlap = TRUE,
    angle = textAngleCalc(df$mpg, df$hp, ratio = 2, max = 10),
    hjust = textHjustCalc(xvec = df$mpg, adjust = TRUE)
  ) +
  coord_fixed(ratio = 2, clip = "off")

david-barnett/microViz documentation built on April 17, 2025, 4:25 a.m.