Extract a Substring From or Replace a Substring In a Character Vector
stri_sub extracts particular substrings at code point-based
index ranges provided. Its replacement version allows to substitute
(in-place) parts of
a string with given replacement strings. stri_sub_replace
is its magrittr's pipe-operator-friendly variant that returns
a copy of the input vector.
For extracting/replacing multiple substrings from/within each string, see
stri_sub_all.
stri_sub(str, from = 1L, to = -1L, length) stri_sub(str, from=1L, to=-1L, length, omit_na=FALSE) <- value stri_sub_replace(..., replacement, value = replacement)
str |
a character vector |
from |
an integer vector giving the start indexes or a two-column matrix
of type |
to |
an integer vector giving the end indexes; mutually exclusive with
|
length |
an integer vector giving the substring lengths;
mutually exclusive with |
omit_na |
a single logical value; indicates whether missing values
in any of the indexes or in |
value |
a character vector defining the replacement strings [replacement function only] |
... |
arguments to be passed to |
replacement |
alias of |
Vectorized over str, [value], from and
(to or length). Parameters
to and length are mutually exclusive.
Indexes are 1-based, i.e., the start of a string is at index 1.
For negative indexes in from or to,
counting starts at the end of the string.
For instance, index -1 denotes the last code point in the string.
Non-positive length gives an empty string.
Argument from gives the start of a substring to extract.
Argument to defines the last index of a substring, inclusive.
Alternatively, its length may be provided.
If from is a two-column matrix, then these two columns are
used as from and to, respectively, and anything passed
explicitly as from or to is ignored.
Such types of index matrices are generated by stri_locate_first
and stri_locate_last. If extraction based on
stri_locate_all is needed, see
stri_sub_all.
In stri_sub, out-of-bound indexes are silently
corrected. If from > to, then an empty string is returned.
In stri_sub<-, some configurations of indexes may work as
substring 'injection' at the front, back, or in middle.
If both to and length are provided,
length has priority over to.
Note that for some Unicode strings, the extracted substrings might not
be well-formed, especially if input strings are not NFC-normalized
(see stri_trans_nfc),
include byte order marks, Bidirectional text marks, and so on.
Handle with care.
stri_sub and stri_sub_replace return a character vector.
stri_sub<- changes the str object in-place.
Other indexing:
stri_locate_all_boundaries(),
stri_locate_all(),
stri_sub_all()
s <- 'Lorem ipsum dolor sit amet, consectetur adipisicing elit.'
stri_sub(s, from=1:3*6, to=21)
stri_sub(s, from=c(1,7,13), length=5)
stri_sub(s, from=1, length=1:3)
stri_sub(s, -17, -7)
stri_sub(s, -5, length=4)
(stri_sub(s, 1, 5) <- 'stringi')
(stri_sub(s, -6, length=5) <- '.')
(stri_sub(s, 1, 1:3) <- 1:2)
x <- c('12 3456 789', 'abc', '', NA, '667')
stri_sub(x, stri_locate_first_regex(x, '[0-9]+')) # see stri_extract_first
stri_sub(x, stri_locate_last_regex(x, '[0-9]+')) # see stri_extract_last
stri_sub_replace(x, stri_locate_first_regex(x, '[0-9]+'),
omit_na=TRUE, replacement='***') # see stri_replace_first
stri_sub_replace(x, stri_locate_last_regex(x, '[0-9]+'),
omit_na=TRUE, replacement='***') # see stri_replace_last
stri_sub(x, stri_locate_first_regex(x, '[0-9]+'), omit_na=TRUE) <- '***'
print(x)
## Not run: x %>% stri_sub_replace(1, 5, replacement='new_substring')Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.