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Apply template function to each element of a vector

map_tags.Rd

map_tags() returns a type-safe tag list, where each element is resolved by applying .f to each element of .x. If an element in .x is a falsey value (i.e. NA, NaN, FALSE, or NULL), the fallback value from .empty is used.

Additional arguments should be passed with an anonymous function.

Usage

map_tags(.x, .f, .empty = NULL)

Arguments

.x

list or atomic vector

.f

a function that takes a single argument returns a character vector, tag, or tagList.

.empty

fallback value for falsey elements

Details

Element values are evaluated prior to returning the tag list:

  • NULL values are removed from the final tag list. The return length of map_tags() is therefore less than or equal to the length of .x

  • All return values must be either a "shiny.tag", "shiny.tag.list", or "character" vector. An error is raised if an unexpected value is encountered.

See also

template, base::lapply, htmltools::tagList

Examples

tpl <- template(x, {p(x)})
map_tags(seq(5L), tpl)
#> <p>1</p>
#> <p>2</p>
#> <p>3</p>
#> <p>4</p>
#> <p>5</p>

# falsey values are removed
map_tags(c(TRUE, FALSE, TRUE), tpl)
#> <p>TRUE</p>
#> <p>TRUE</p>