Collapse a vector into a string scalar

Features:

• custom separator (sep),

• custom separator for length-two input (sep2),

• custom last separator (last),

• adds ellipsis to truncated strings,

• uses Unicode ellipsis character on UTF-8 console,

• can collapse "from both ends", with style = "both-ends",

• can consider a limit for the display width of the result, in characters,

• handles ANSI control sequences correctly when measuring display width.

Usage

ansi_collapse(
  x,
  sep = ", ",
  sep2 = sub("^,", "", last),
  last = ", and ",
  trunc = Inf,
  width = Inf,
  ellipsis = symbol$ellipsis,
  style = c("both-ends", "head")
)

Arguments

x

Character vector, or an object with an as.character() method to collapse.

sep

Separator. A character string.

sep2

Separator for the special case that x contains only two elements. A character string. Defaults to the value of last without the serial comma.

last

Last separator, if there is no truncation. E.g. use ", and " for the serial comma. A character string.

trunc

Maximum number of elements to show. For style = "head" at least trunc = 1 is used. For style = "both-ends" at least trunc = 5 is used, even if a smaller number is specified.

width

Limit for the display width of the result, in characters. This is a hard limit, and the output will never exceed it. This argument is not implemented for the "both-ends" style, which always uses Inf, with a warning if a finite width value is set.

ellipsis

Character string to use at the place of the truncation. By default, the Unicode ellipsis character is used if the console is UTF-8, and three dots otherwise.

style

Truncation style:

• both-ends: the default, shows the beginning and end of the vector, and skips elements in the middle if needed.

• head: shows the beginning of the vector, and skips elements at the end, if needed.

Value

Character scalar. It is NA_character_ if any elements in x are NA.

See also

glue_collapse in the glue package inspired this function.

Examples

ansi_collapse(letters)
#> [1] "a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, and z"

# truncate
ansi_collapse(letters, trunc = 5)
#> [1] "a, b, c, …, y, and z"

# head style
ansi_collapse(letters, trunc = 5, style = "head")
#> [1] "a, b, c, d, e, …"