Word Wrap Text to Format Paragraphs
This function breaks text paragraphs into lines,
of total width (if it is possible) at most given width.
stri_wrap(
str,
width = floor(0.9 * getOption("width")),
cost_exponent = 2,
simplify = TRUE,
normalize = TRUE,
normalise = normalize,
indent = 0,
exdent = 0,
prefix = "",
initial = prefix,
whitespace_only = FALSE,
use_length = FALSE,
locale = NULL
)str |
character vector of strings to reformat |
width |
single integer giving the suggested maximal number of code points per line |
cost_exponent |
single numeric value, values not greater than zero will select a greedy word-wrapping algorithm; otherwise this value denotes the exponent in the cost function of a (more aesthetic) dynamic programming-based algorithm (values in [2, 3] are recommended) |
simplify |
single logical value, see Value |
normalize |
single logical value, see Details |
normalise |
alias of |
indent |
single non-negative integer; gives the indentation of the first line in each paragraph |
exdent |
single non-negative integer; specifies the indentation of subsequent lines in paragraphs |
prefix, initial |
single strings; |
whitespace_only |
single logical value; allow breaks only at white-spaces?
if |
use_length |
single logical value; should the number of code
points be used instead of the total code point width (see |
locale |
|
Vectorized over str.
If whitespace_only is FALSE,
then ICU's line-BreakIterator is used to determine
text boundaries where a line break is possible.
This is a locale-dependent operation.
Otherwise, the breaks are only at white-spaces.
Note that Unicode code points may have various widths when
printed on the console and that the function takes that by default
into account. By changing the state of the use_length
argument, this function starts to act like each code point
was of width 1. This feature should rather be used with
text in Latin script.
If normalize is FALSE,
then multiple white spaces between the word boundaries are
preserved within each wrapped line.
In such a case, none of the strings can contain \r, \n,
or other new line characters, otherwise you will get an error.
You should split the input text into lines
or, for example, substitute line breaks with spaces
before applying this function.
If normalize is TRUE, then
all consecutive white space (ASCII space, horizontal TAB, CR, LF)
sequences are replaced with single ASCII spaces
before actual string wrapping. Moreover, stri_split_lines
and stri_trans_nfc is called on the input character vector.
This is for compatibility with strwrap.
The greedy algorithm (for cost_exponent being non-positive)
provides a very simple way for word wrapping.
It always puts as many words in each line as possible.
This method – contrary to the dynamic algorithm – does not minimize
the number of space left at the end of every line.
The dynamic algorithm (a.k.a. Knuth's word wrapping algorithm)
is more complex, but it returns text wrapped
in a more aesthetic way. This method minimizes the squared
(by default, see cost_exponent) number of spaces (raggedness)
at the end of each line, so the text is mode arranged evenly.
Note that the cost of printing the last line is always zero.
If simplify is TRUE, then a character vector is returned.
Otherwise, you will get a list of length(str) character vectors.
D.E. Knuth, M.F. Plass, Breaking paragraphs into lines, Software: Practice and Experience 11(11), 1981, pp. 1119–1184
Other locale_sensitive:
%s<%(),
about_locale,
about_search_boundaries,
about_search_coll,
stri_compare(),
stri_count_boundaries(),
stri_duplicated(),
stri_enc_detect2(),
stri_extract_all_boundaries(),
stri_locate_all_boundaries(),
stri_opts_collator(),
stri_order(),
stri_rank(),
stri_sort_key(),
stri_sort(),
stri_split_boundaries(),
stri_trans_tolower(),
stri_unique()
Other text_boundaries:
about_search_boundaries,
about_search,
stri_count_boundaries(),
stri_extract_all_boundaries(),
stri_locate_all_boundaries(),
stri_opts_brkiter(),
stri_split_boundaries(),
stri_split_lines(),
stri_trans_tolower()
s <- stri_paste( 'Lorem ipsum dolor sit amet, consectetur adipisicing elit. Proin ', 'nibh augue, suscipit a, scelerisque sed, lacinia in, mi. Cras vel ', 'lorem. Etiam pellentesque aliquet tellus.') cat(stri_wrap(s, 20, 0.0), sep='\n') # greedy cat(stri_wrap(s, 20, 2.0), sep='\n') # dynamic cat(stri_pad(stri_wrap(s), side='both'), sep='\n')
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