str_view() is used to print the underlying representation of a string and
to see how a pattern matches.
Matches are surrounded by <> and unusual whitespace (i.e. all whitespace
apart from " " and "\n") are surrounded by {} and escaped. Where
possible, matches and unusual whitespace are coloured blue and NAs red.
str_view(
string,
pattern = NULL,
match = TRUE,
html = FALSE,
use_escapes = FALSE
)Input vector. Either a character vector, or something coercible to one.
Pattern to look for.
The default interpretation is a regular expression, as described in
vignette("regular-expressions"). Use regex() for finer control of the
matching behaviour.
Match a fixed string (i.e. by comparing only bytes), using
fixed(). This is fast, but approximate. Generally,
for matching human text, you'll want coll() which
respects character matching rules for the specified locale.
Match character, word, line and sentence boundaries with
boundary(). An empty pattern, "", is equivalent to
boundary("character").
If pattern is supplied, which elements should be shown?
TRUE, the default, shows only elements that match the pattern.
NA shows all elements.
FALSE shows only elements that don't match the pattern.
If pattern is not supplied, all elements are always shown.
Use HTML output? If TRUE will create an HTML widget; if FALSE
will style using ANSI escapes.
If TRUE, all non-ASCII characters will be rendered
with unicode escapes. This is useful to see exactly what underlying
values are stored in the string.
# Show special characters
str_view(c("\"\\", "\\\\\\", "fgh", NA, "NA"))
#> [1] │ "\
#> [2] │ \\\
#> [3] │ fgh
#> [4] │ NA
#> [5] │ NA
# A non-breaking space looks like a regular space:
nbsp <- "Hi\u00A0you"
nbsp
#> [1] "Hi you"
# But it doesn't behave like one:
str_detect(nbsp, " ")
#> [1] FALSE
# So str_view() brings it to your attention with a blue background
str_view(nbsp)
#> [1] │ Hi{\u00a0}you
# You can also use escapes to see all non-ASCII characters
str_view(nbsp, use_escapes = TRUE)
#> [1] │ Hi\u00a0you
# Supply a pattern to see where it matches
str_view(c("abc", "def", "fghi"), "[aeiou]")
#> [1] │ <a>bc
#> [2] │ d<e>f
#> [3] │ fgh<i>
str_view(c("abc", "def", "fghi"), "^")
#> [1] │ <>abc
#> [2] │ <>def
#> [3] │ <>fghi
str_view(c("abc", "def", "fghi"), "..")
#> [1] │ <ab>c
#> [2] │ <de>f
#> [3] │ <fg><hi>
# By default, only matching strings will be shown
str_view(c("abc", "def", "fghi"), "e")
#> [2] │ d<e>f
# but you can show all:
str_view(c("abc", "def", "fghi"), "e", match = NA)
#> [1] │ abc
#> [2] │ d<e>f
#> [3] │ fghi
# or just those that don't match:
str_view(c("abc", "def", "fghi"), "e", match = FALSE)
#> [1] │ abc
#> [3] │ fghi