Rcpp中字符串与单个值的矢量化比较

这个 == Rcpp中的运算符在将数字向量与单个值进行比较时按预期工作。即,将向量的每个元素与值进行比较,并返回一个逻辑向量。例如,考虑以下行为符合预期:

library(Rcpp)
cppFunction('
CharacterVector test_vals(NumericVector x) {
  if (is_true(any(x == 3))) return ("Values include 3");
  return ("3 not found");
}')
test_vals(1:2)
# [1] "3 not found"
test_vals(1:5)
# [1] "Values include 3"

但是,如果我尝试将字符向量与字符标量进行比较,它似乎只测试向量的第一个元素:

cppFunction('
CharacterVector test_names(NumericVector x) {
  CharacterVector y = x.attr("names");
  if (is_true(any(y == CharacterVector::create("foo")))) return ("Names include foo");
  return ("foo not found");
}')
test_names(c(a=1, b=2, foo=3))
# [1] "foo not found"
test_names(c(foo=3, a=1, b=2))
# [1] "Names include foo"

我知道比较两个相同长度的字符向量似乎是以向量化的方式工作的,正如预期的那样:

cppFunction('
CharacterVector test_names(NumericVector x) {
  CharacterVector y = x.attr("names");
  CharacterVector foo(x.size());
  foo.fill("foo");
  if (is_true(any(y == foo))) return ("Names include foo");
  return ("foo not found");
}')
test_names(c(a=1, b=2, foo=3))
# [1] "Names include foo"
test_names(c(foo=3, a=1, b=2))
# [1] "Names include foo"
test_names(c(a=1, b=2))
# [1] "foo not found"

这是否意味着字符向量与单个值的比较还没有实现 Rcpp 或者我只是想知道怎么做?