Get a LaTeX equation from a model or from LaTeX code

Extract or create a LaTeX equation to describe a model, or directly from LaTeX code. All objects supported by equatiomatic::extract_eq() are supported by the default method description.

Usage

equation(object, ...)

# S3 method for default
equation(
  object,
  auto.labs = TRUE,
  origdata = NULL,
  labs = NULL,
  swap_var_names = NULL,
  ...
)

# S3 method for character
equation(object, ...)

eq__(object, ...)

eq_(object, ...)

# S3 method for inline_equation
print(x, ...)

Arguments

object: An object with a model whose the equation is constructed. If a character object is provided, it is concatenated into a single character string and the equation class, otherwise non transformed (it is supposed to be a valid LaTeX equation). Remember that backslashes must be doubled in regular R strings, or use the r"(...)" notation, which may be more comfortable here, see examples.
...: Further parameters passed to equatiomatic::extract_eq() (see its man page).
auto.labs: If TRUE (by default), use labels (and units) automatically from data or origdata=.
origdata: The original data set this model was fitted to. By default it is NULL and no label is used.
labs: Labels to change the names of elements in the term column of the table. By default it is NULL and no term is changed.
swap_var_names: Change the variable names for these values, regardless of the values in auto.labs= or labs= that are ignored if this argument is used. Provide a named character string with name being the variables and strings the new names. You can use ^ or _ to indicate next character, or next integer should be super) or subscript in the equation.
x: An inline_equation object generated by eq_().`

Value

An object of class c("equation", "character").

Details

There are slight differences between equation(), eq_() and eq__():

equation() returns a string with LaTeX code and prints LaTeX code at the R console.
eq_() returns the LaTeX code surrounded by a dollar sign $...$ and is suitable to build inline equations in R Markdown/Quarto documents by using inline R code. It prints the rendered inline equation in the RStudio Viewer or in the browser. So it is advised to rapidly preview the resulting equation.
eq__() returns the LaTeX code not surrounded by dollar signs in a simple character string. It just prompts the LaTeX string in the R console. It should be used in an R inline chunk inside a $$...$$ construct in a Markdown text. The result is a display equation that can also be cross referenced in Quarto in the usual way if you label it, e.g., you use $$...$$ {#eq-label}.

Examples

iris_lm <- lm(data = iris, Petal.Length ~ Sepal.Length + Species)
summary(iris_lm)
#> 
#> Call:
#> lm(formula = Petal.Length ~ Sepal.Length + Species, data = iris)
#> 
#> Residuals:
#>      Min       1Q   Median       3Q      Max 
#> -0.76390 -0.17875  0.00716  0.17461  0.79954 
#> 
#> Coefficients:
#>                   Estimate Std. Error t value Pr(>|t|)    
#> (Intercept)       -1.70234    0.23013  -7.397 1.01e-11 ***
#> Sepal.Length       0.63211    0.04527  13.962  < 2e-16 ***
#> Speciesversicolor  2.21014    0.07047  31.362  < 2e-16 ***
#> Speciesvirginica   3.09000    0.09123  33.870  < 2e-16 ***
#> ---
#> Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
#> 
#> Residual standard error: 0.2826 on 146 degrees of freedom
#> Multiple R-squared:  0.9749,	Adjusted R-squared:  0.9744 
#> F-statistic:  1890 on 3 and 146 DF,  p-value: < 2.2e-16
#> 
equation(iris_lm)
#> $$
#> \operatorname{Petal.Length} = \alpha + \beta_{1}(\operatorname{Sepal.Length}) + \beta_{2}(\operatorname{Species}_{\operatorname{versicolor}}) + \beta_{3}(\operatorname{Species}_{\operatorname{virginica}}) + \epsilon
#> $$
# Providing directly the LaTeX code of the equation (variance of a sample)
equation("S^2_y = \\sum_{i=1}^{n-1} \\frac{(y_i - \\bar{Y})^2}{n}")
#> $$
#> S^2_y = \sum_{i=1}^{n-1} \frac{(y_i - \bar{Y})^2}{n}
#> $$
# Easier to write like this (avoiding the double backslashes):
eq1 <- equation(r"(S^2_y = \sum_{i=1}^{n-1} \frac{(y_i - \bar{Y})^2}{n})")
# Print raw text:
eq1
#> $$
#> S^2_y = \sum_{i=1}^{n-1} \frac{(y_i - \bar{Y})^2}{n}
#> $$
# Get a preview of the equation
eq__(eq1)
#> [1] "S^2_y = \\sum_{i=1}^{n-1} \\frac{(y_i - \\bar{Y})^2}{n}"
# The same function can be used inside a `$$...$$ {#eq-label}` construct in
# R Markdown or Quarto to calcule a display equation that is also recognized
# by the cross referencing system of Quarto.
# Get a string suitable for inclusion inline in R Markdown with `r eq_(eq1)`
# (inside Markdown text and without the dollar signs around it)
eq_(eq1)