stringr 1.5.1

• Some minor documentation improvements.

• str_trunc() now correctly truncates strings when side is "left" or
  "center" (@UchidaMizuki, #512).

stringr 1.5.0

Breaking changes

• stringr functions now consistently implement the tidyverse recycling rules
  (#372). There are two main changes:

  • Only vectors of length 1 are recycled. Previously, (e.g.)
    str_detect(letters, c("x", "y")) worked, but it now errors.

  • str_c() ignores NULLs, rather than treating them as length 0
    vectors.

  Additionally, many more arguments now throw errors, rather than warnings,
  if supplied the wrong type of input.

• regex() and friends now generate class names with stringr_ prefix (#384).

• str_detect(), str_starts(), str_ends() and str_subset() now error
  when used with either an empty string ("") or a boundary(). These
  operations didn't really make sense (str_detect(x, "") returned TRUE
  for all non-empty strings) and made it easy to make mistakes when programming.

New features

• Many tweaks to the documentation to make it more useful and consistent.

• New vignette("from-base") by @sastoudt provides a comprehensive comparison
  between base R functions and their stringr equivalents. It's designed to
  help you move to stringr if you're already familiar with base R string
  functions (#266).

• New str_escape() escapes regular expression metacharacters, providing
  an alternative to fixed() if you want to compose a pattern from user
  supplied strings (#408).

• New str_equal() compares two character vectors using unicode rules,
  optionally ignoring case (#381).

• str_extract() can now optionally extract a capturing group instead of
  the complete match (#420).

• New str_flatten_comma() is a special case of str_flatten() designed for
  comma separated flattening and can correctly apply the Oxford commas
  when there are only two elements (#444).

• New str_split_1() is tailored for the special case of splitting up a single
  string (#409).

• New str_split_i() extract a single piece from a string (#278, @bfgray3).

• New str_like() allows the use of SQL wildcards (#280, @rjpat).

• New str_rank() to complete the set of order/rank/sort functions (#353).

• New str_sub_all() to extract multiple substrings from each string.

• New str_unique() is a wrapper around stri_unique() and returns unique
  string values in a character vector (#249, @seasmith).

• str_view() uses ANSI colouring rather than an HTML widget (#370). This
  works in more places and requires fewer dependencies. It includes a number
  of other small improvements:

  • It no longer requires a pattern so you can use it to display strings with
    special characters.
  • It highlights unusual whitespace characters.
  • It's vectorised over both stringandpattern` (#407).
  • It defaults to displaying all matches, making str_view_all() redundant
    (and hence deprecated) (#455).

• New str_width() returns the display width of a string (#380).

• stringr is now licensed as MIT (#351).

Minor improvements and bug fixes

• Better error message if you supply a non-string pattern (#378).

• A new data source for sentences has fixed many small errors.

• str_extract() and str_exctract_all() now work correctly when pattern
  is a boundary().

• str_flatten() gains a last argument that optionally override the
  final separator (#377). It gains a na.rm argument to remove missing
  values (since it's a summary function) (#439).

• str_pad() gains use_width argument to control whether to use the total
  code point width or the number of code points as "width" of a string (#190).

• str_replace() and str_replace_all() can use standard tidyverse formula
  shorthand for replacement function (#331).

• str_starts() and str_ends() now correctly respect regex operator
  precedence (@carlganz).

• str_wrap() breaks only at whitespace by default; set
  whitespace_only = FALSE to return to the previous behaviour (#335, @rjpat).

• word() now returns all the sentence when using a negative start parameter
  that is greater or equal than the number of words. (@pdelboca, #245)

stringr 1.4.1

Hot patch release to resolve R CMD check failures.

stringr 1.4.0

• str_interp() now renders lists consistently independent on the presence of
  additional placeholders (@amhrasmussen).

• New str_starts() and str_ends() functions to detect patterns at the
  beginning or end of strings (@jonthegeek, #258).

• str_subset(), str_detect(), and str_which() get negate argument,
  which is useful when you want the elements that do NOT match (#259,
  @yutannihilation).

• New str_to_sentence() function to capitalize with sentence case
  (@jonthegeek, #202).

stringr 1.3.1

• str_replace_all() with a named vector now respects modifier functions (#207)

• str_trunc() is once again vectorised correctly (#203, @austin3dickey).

• str_view() handles NA values more gracefully (#217). I've also
  tweaked the sizing policy so hopefully it should work better in notebooks,
  while preserving the existing behaviour in knit documents (#232).

stringr 1.3.0

API changes

• During package build, you may see
  Error : object ‘ignore.case’ is not exported by 'namespace:stringr'.
  This is because the long deprecated str_join(), ignore.case() and
  perl() have now been removed.

New features

• str_glue() and str_glue_data() provide convenient wrappers around
  glue and glue_data() from the glue package
  (#157).

• str_flatten() is a wrapper around stri_flatten() and clearly
  conveys flattening a character vector into a single string (#186).

• str_remove() and str_remove_all() functions. These wrap
  str_replace() and str_replace_all() to remove patterns from strings.
  (@Shians, #178)

• str_squish() removes spaces from both the left and right side of strings,
  and also converts multiple space (or space-like characters) to a single
  space within strings (@stephlocke, #197).

• str_sub() gains omit_na argument for ignoring NA. Accordingly,
  str_replace() now ignores NAs and keeps the original strings.
  (@yutannihilation, #164)

Bug fixes and minor improvements

• str_trunc() now preserves NAs (@ClaytonJY, #162)

• str_trunc() now throws an error when width is shorter than ellipsis
  (@ClaytonJY, #163).

• Long deprecated str_join(), ignore.case() and perl() have now been
  removed.

stringr 1.2.0

stringr 1.2.0

API changes

• str_match_all() now returns NA if an optional group doesn't match
  (previously it returned ""). This is more consistent with str_match()
  and other match failures (#134).

New features

• In str_replace(), replacement can now be a function that is called once
  for each match and who's return value is used to replace the match.
• New str_which() mimics grep() (#129).
• A new vignette (vignette("regular-expressions")) describes the
  details of the regular expressions supported by stringr.
  The main vignette (vignette("stringr")) has been updated to
  give a high-level overview of the package.

Minor improvements and bug fixes

• str_order() and str_sort() gain explicit numeric argument for sorting
  mixed numbers and strings.
• str_replace_all() now throws an error if replacement is not a character
  vector. If replacement is NA_character_ it replaces the complete string
  with replaces with NA (#124).
• All functions that take a locale (e.g. str_to_lower() and str_sort())
  default to "en" (English) to ensure that the default is consistent across
  platforms.

stringr 1.1.0

• Add sample datasets: fruit, words and sentences.
• fixed(), regex(), and coll() now throw an error if you use them with
  anything other than a plain string (#60). I've clarified that the replacement
  for perl() is regex() not regexp() (#61). boundary() has improved
  defaults when splitting on non-word boundaries (#58, @lmullen).
• str_detect() now can detect boundaries (by checking for a str_count() > 0)
  (#120). str_subset() works similarly.
• str_extract() and str_extract_all() now work with boundary(). This is
  particularly useful if you want to extract logical constructs like words
  or sentences. str_extract_all() respects the simplify argument
  when used with fixed() matches.
• str_subset() now respects custom options for fixed() patterns
  (#79, @gagolews).
• str_replace() and str_replace_all() now behave correctly when a
  replacement string contains $s, \\\\1, etc. (#83, #99).
• str_split() gains a simplify argument to match str_extract_all()
  etc.
• str_view() and str_view_all() create HTML widgets that display regular
  expression matches (#96).
• word() returns NA for indexes greater than number of words (#112).

stringr 1.0.0

• stringr is now powered by stringi instead of base R regular expressions. This improves unicode and support, and makes most operations considerably faster. If you find stringr inadequate for your string processing needs, I highly recommend looking at stringi in more detail.

• stringr gains a vignette, currently a straight forward update of the article that appeared in the R Journal.

• str_c() now returns a zero length vector if any of its inputs are zero length vectors. This is consistent with all other functions, and standard R recycling rules. Similarly, using str_c("x", NA) now yields NA. If you want "xNA", use str_replace_na() on the inputs.

• str_replace_all() gains a convenient syntax for applying multiple pairs of pattern and replacement to the same vector:

  input <- c("abc", "def")
  str_replace_all(input, c("[ad]" = "!", "[cf]" = "?"))

• str_match() now returns NA if an optional group doesn't match (previously it returned ""). This is more consistent with str_extract() and other match failures.

• New str_subset() keeps values that match a pattern. It's a convenient wrapper for x[str_detect(x)] (#21, @jiho).

• New str_order() and str_sort() allow you to sort and order strings in a specified locale.

• New str_conv() to convert strings from specified encoding to UTF-8.

• New modifier boundary() allows you to count, locate and split by character, word, line and sentence boundaries.

• The documentation got a lot of love, and very similar functions (e.g. first and all variants) are now documented together. This should hopefully make it easier to locate the function you need.

• ignore.case(x) has been deprecated in favour of fixed|regexp|coll(x, ignore.case = TRUE), perl(x) has been deprecated in favour of regexp(x).

• str_join() is deprecated, please use str_c() instead.