Define a user-level LaTeX macro

Registers a zero-argument shorthand that is expanded by text substitution before the expression reaches the MicroTeX parser. Useful for domain-specific notation (e.g. \RR for \mathbb{R}) you reuse across many plots.

Usage

define_macro(name, definition)

clear_macros(name = NULL)

list_macros()

Arguments

name

Macro name without the leading backslash. For clear_macros, the macro name to drop, or NULL (default) to clear all.

definition

LaTeX source the macro expands to.

Value

• define_macro: Invisibly returns NULL.

• clear_macros: Invisibly returns NULL.

• list_macros: A named character vector mapping macro names to their expansions. Empty if no macros are defined.

Choosing between this and \newcommand

MicroTeX also accepts \newcommand and plain-TeX \def written inside the expression itself, and those are the more capable form: they take up to nine arguments, which define_macro() does not — it substitutes text and nothing else.

  # parameterised, but local to this one expression
  grid.latex(r"(\def\norm#1{\left\lVert #1 \right\rVert}
                \norm{\vec{v}})")

What they cannot do is persist: the user-macro table is cleared at the start of every parse, so a \newcommand written in one call is gone by the next. That is the one thing define_macro() is for. Use \newcommand / \def for an abbreviation local to a single label, and define_macro() for notation you want available to every label in a script.

See also

latex_grob, latex_options

Examples

# \donttest{
  define_macro("RR", "\\mathbb{R}")
  define_macro("eps", "\\varepsilon")
  grid::grid.newpage()
  grid.latex("\\forall \\eps > 0, \\eps \\in \\RR")

  clear_macros()
# }