Add points to texture triangle — add_texture

To vary color, symbol, and size of points by a grouping variable, call this function once for each value of the grouping variable. Add layers from bottom to top. The below example adds the red points last so they are plotted on top of the gray points.

Usage

add_texture_points(
  texture_df = NULL,
  color = "#a60f2dCC",
  pch = 19,
  size = 1.5,
  ...
)

Source

Adapted from plotrix: https://github.com/plotrix/plotrix/blob/0d4c2b065e2c2d327358ac8cdc0b0d46b89bea7f/R/soil.texture.R

Arguments

texture_df: Data frame or matrix where each row is a soil sample and three numeric columns contain sand, silt, and clay percentages or proportions. The order of sand, silt, clay is required for correct plotting.
color: Color of the points. Defaults to WaSHI red.
pch: Numeric value of plotting symbol. See graphics::points() for options and details. Defaults to 19, which is a filled-in circle.
size: Numeric expansion factor for points. Defaults to 1.5.
...: Other arguments passed to graphics::points().

Value

A list of x, y coordinates of the soil textures plotted.

Examples

texture <- soils::washi_data |>
  dplyr::select(
    sand = sand_percent,
    silt = silt_percent,
    clay = clay_percent
  )

make_texture_triangle(body_font = "sans")

# Add gray points
add_texture_points(
  tail(texture, 5),
  color = "#3E3D3D90",
  pch = 19
)

# Add red points
add_texture_points(
  head(texture, 5),
  color = "#a60f2dCC",
  pch = 15
)


# Note the text appears squished in this example since the width, height,
# and resolution have been optimized to print the figure 6 in wide in the
# report.