1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
|
#' Flatten a string
#
#' @description
#' `str_flatten()` reduces a character vector to a single string. This is a
#' summary function because regardless of the length of the input `x`, it
#' always returns a single string.
#'
#' `str_flatten_comma()` is a variation designed specifically for flattening
#' with commas. It automatically recognises if `last` uses the Oxford comma
#' and handles the special case of 2 elements.
#'
#' @inheritParams str_detect
#' @param collapse String to insert between each piece. Defaults to `""`.
#' @param last Optional string to use in place of the final separator.
#' @param na.rm Remove missing values? If `FALSE` (the default), the result
#' will be `NA` if any element of `string` is `NA`.
#' @return A string, i.e. a character vector of length 1.
#' @export
#' @examples
#' str_flatten(letters)
#' str_flatten(letters, "-")
#'
#' str_flatten(letters[1:3], ", ")
#'
#' # Use last to customise the last component
#' str_flatten(letters[1:3], ", ", " and ")
#'
#' # this almost works if you want an Oxford (aka serial) comma
#' str_flatten(letters[1:3], ", ", ", and ")
#'
#' # but it will always add a comma, even when not necessary
#' str_flatten(letters[1:2], ", ", ", and ")
#'
#' # str_flatten_comma knows how to handle the Oxford comma
#' str_flatten_comma(letters[1:3], ", and ")
#' str_flatten_comma(letters[1:2], ", and ")
str_flatten <- function(string, collapse = "", last = NULL, na.rm = FALSE) {
check_string(collapse)
check_string(last, allow_null = TRUE)
check_bool(na.rm)
if (na.rm) {
string <- string[!is.na(string)]
}
n <- length(string)
if (!is.null(last) && n >= 2) {
string <- c(
string[seq2(1, n - 2)],
stringi::stri_c(string[[n - 1]], last, string[[n]])
)
}
stri_flatten(string, collapse = collapse)
}
#' @export
#' @rdname str_flatten
str_flatten_comma <- function(string, last = NULL, na.rm = FALSE) {
check_string(last, allow_null = TRUE)
check_bool(na.rm)
# Remove comma if exactly two elements, and last uses Oxford comma
if (length(string) == 2 && !is.null(last) && str_detect(last, "^,")) {
last <- str_replace(last, "^,", "")
}
str_flatten(string, ", ", last = last, na.rm = na.rm)
}
|
