Plot the parse tree of a formula

Requires the igraph and ggraph packages, which you can install with install.packages(c("igraph", "ggraph")). Draws a simple tree plot of the parse tree, showing parent-child relationships, tokens and types.

The utility functions lexl_edges(), lexl_vertices(), and lexl_igraph() compute each stage in plotting the final graph.

# S3 method for lexl
plot(x, ...)

lexl_edges(x)

lexl_vertices(x)

lexl_igraph(x)

Arguments

x	parse tree from lexl()
...	ignored, for consistency with the base plot() function

See also

lexl::lex_xl(), lexl::demo_lexl()

Examples

x <- lex_xl("MIN(3,MAX(2,A1))")

lexl_edges(x)
#>    from to
#> 1     0  1
#> 2     0  2
#> 3     0 11
#> 4     2  3
#> 5     2  4
#> 6     2  5
#> 7     2  6
#> 8     2 10
#> 9     6  7
#> 10    6  8
#> 11    6  9
lexl_vertices(x)
#>    id         label      type token
#> 1   0          root      root  root
#> 2   1 MIN\nfunction  function   MIN
#> 3   2   (\nfun_open  fun_open     (
#> 4   3     3\nnumber    number     3
#> 5   4  ,\nseparator separator     ,
#> 6   5 MAX\nfunction  function   MAX
#> 7   6   (\nfun_open  fun_open     (
#> 8   7     2\nnumber    number     2
#> 9   8  ,\nseparator separator     ,
#> 10  9       A1\nref       ref    A1
#> 11 10  )\nfun_close fun_close     )
#> 12 11  )\nfun_close fun_close     )

if (interactive() && require(igraph, quietly = TRUE)) {
  lexl_igraph(x)
}

if (interactive()
    && require(igraph, quietly = TRUE)
    && require(ggraph, quietly = TRUE)) {
  plot(x)
}