2D Slice to R Plot — add_slice

Take a slice from a linear model and add the displayed graph to a preexisting R plot. This function is similar to slice_2d() but adds a line to an existing plot rather than creating a new one. Useful for overlaying multiple model slices or adding model predictions to scatter plots.

Usage

add_slice_2d(
  model,
  x_axis = NA,
  n = 100,
  caption = FALSE,
  back_transform = TRUE,
  interval = "none",
  ...,
  xaxis = NULL
)

Arguments

model: A linear model
x_axis: A non-required specification of the x-axis variable; default is the first x var in the lm. May also be an expression of the model's predictors, such as x_axis = "x * x_pos", in which case predictions are made at the model's own data points and placed at the expression's value.
n: Number of displayed points; default is 100
caption: Boolean to include caption with values of predictor variables not shown in the chart, FALSE by default
back_transform: How to map predictions onto the y-axis when the model's response is transformed. Default TRUE auto-detects from the model formula; FALSE turns back-transformation off; a one-argument function (e.g. exp) or a name ("log", "log10", "log2", "sqrt", "exp", "inverse") applies that transformation.
interval: Draw a shaded band around the line: "none" (default), or "confidence" / "prediction" for the corresponding predict.lm() interval.
...: Remaining vars (color, linetype, etc.)
xaxis: Deprecated; use x_axis instead.

Value

A line added to a preexisting R plot displaying a 2D graphable slice of an HD model

Examples

model <- lm(log(mpg) ~ disp + hp, data = mtcars)
plot(mpg ~ disp, data = mtcars)
add_slice_2d(model)
#> X-axis not specified - Used first x variable as x-axis
#>     To specify, use 'x_axis = "var_name"' such as 'x_axis = "disp"'
#> Value for `hp` not specified - Used mean: 146.7
#>     To specify, use 'var_name = value', such as 'hp = 146.7'


# Multiple slices on one plot
plot(mpg ~ disp, data = mtcars)
add_slice_2d(model, hp = min(mtcars$hp), col = "blue")
#> X-axis not specified - Used first x variable as x-axis
#>     To specify, use 'x_axis = "var_name"' such as 'x_axis = "disp"'
add_slice_2d(model, hp = max(mtcars$hp), col = "red", lty = 2)
#> X-axis not specified - Used first x variable as x-axis
#>     To specify, use 'x_axis = "var_name"' such as 'x_axis = "disp"'