stri_sub
Extract a Substring From or Replace a Substring In a Character Vector
The first function extracts substrings under code point-based index ranges provided. The second one allows to substitute parts of a string with given strings.
Usage
stri_sub(str, from = 1L, to = -1L, length)stri_sub(str, from = 1L, to = -1L, length) <- value
Arguments
- str
- character vector
- from
- integer vector or two-column matrix
- to
- integer vector; mutually exclusive with
lengthandfrombeing a matrix - length
- integer vector; mutually exclusive with
toandfrombeing a matrix - value
- character vector to be substituted [replacement function]
Details
Vectorized over str, [value], from and
(to or length).
to and length are mutually exclusive.
to has priority over length.
If from is a two-column matrix, then the first column is used
as from and the second one as to. In such case arguments
to and length are ignored.
Of course, the indices are code point-based,
and not byte-based.
Note that for some Unicode strings, the extracted substrings may not
be well-formed, especially if the input is not NFC-normalized
(see stri_trans_nfc),
includes byte order marks, Bidirectional text marks, and so on.
Handle with care.
Indices are 1-based, i.e. an index equal to 1 denotes the first character
in a string, which gives a typical Rlook-and-feel.
Argument to defines the last index of the substring, inclusive.
For negative indices in from or to,
counting starts at the end of the string.
E.g. index -1 denotes the last code point in the string.
Negative length means counting backwards.
In stri_sub, out-of-bound indices are silently
corrected. If from > to, then an empty string is returned.
In stri_sub<-, ``strange'' configurations of indices work as
string concatenation at the front, back, or middle.
Value
stri_subreturns a character vector.stri_sub<-changes thevalueobject.The extract function
stri_subreturns the indicated substrings. The replacement functionstri_sub<-is invoked for its side effect: after a call,stris modified.
See Also
Other indexing: stri_locate_all_boundaries,
stri_locate_all_words,
stri_locate_first_boundaries,
stri_locate_first_words,
stri_locate_last_boundaries,
stri_locate_last_words;
stri_locate, stri_locate_all,
stri_locate_all_charclass,
stri_locate_all_coll,
stri_locate_all_fixed,
stri_locate_all_regex,
stri_locate_first,
stri_locate_first_charclass,
stri_locate_first_coll,
stri_locate_first_fixed,
stri_locate_first_regex,
stri_locate_last,
stri_locate_last_charclass,
stri_locate_last_coll,
stri_locate_last_fixed,
stri_locate_last_regex
Examples
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)