Determines if entries of
x start or end with string (entries of)
suffix respectively, where strings are
recycled to common lengths.
startsWith(x, prefix) endsWith(x, suffix)
startsWith() is equivalent to but much faster than
substring(x, 1, nchar(prefix)) == prefix
prefix is not to contain special regular expression
characters (and for
x does not contain missing
values, see below).
The code has an optimized branch for the most common usage in which
suffix is of length one, and is further
optimized in a UTF-8 or 8-byte locale if that is an ASCII string.
logical vector, of “common length” of
suffix), i.e., of the longer of the two
lengths unless one of them is zero when the result is
also of zero length. A shorter input is recycled to the output length.
substring; the partial string
solve a different task.
startsWith(search(), "package:") # typically at least two FALSE, nowadays often three x1 <- c("Foobar", "bla bla", "something", "another", "blu", "brown", "blau blüht der Enzian")# non-ASCII x2 <- cbind( startsWith(x1, "b"), startsWith(x1, "bl"), startsWith(x1, "bla"), endsWith(x1, "n"), endsWith(x1, "an")) rownames(x2) <- x1; colnames(x2) <- c("b", "b1", "bla", "n", "an") x2 ## Non-equivalence in case of missing values in 'x', see Details: x <- c("all", "but", NA_character_) cbind(startsWith(x, "a"), substring(x, 1L, 1L) == "a", grepl("^a", x))
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