为什么我的函数要创建重复项?

我编写了一个函数,它可以遍历URL并从每个页面中提取所需的数据。

library(xml2)
library(rvest)

下面创建了相关URL的矢量:

tripadvisor_urls <- c()

for (n in seq(0, 80, 10)) {
    url <- paste('https://www.tripadvisor.co.uk/Attraction_Review-g186306-d9756771-Reviews-or',n,
           '-Suckerpunch_St_Albans-St_Albans_Hertfordshire_England.html', sep = "")
    tripadvisor_urls <- c(tripadvisor_urls, url)
    }

这是我写的函数:

all_pages <- function(x) {
id_v <- c()
rating_v <- c()
headline_quote_v <- c()
date_v <- c()
review_v <- c()
for (url in x) {
        reviews <- url %>%
          read_html() %>%
          html_nodes("#REVIEWS .innerBubble")

        id <- reviews %>%
          html_node(".quote a") %>%
          html_attr("id")
        id_v <- c(id_v, id)

        headline_quote <- reviews %>%
          html_node(".quote span") %>%
          html_text()
        headline_quote_v <- c(headline_quote_v, headline_quote)

        rating_wrong <- url %>%
          read_html() %>%
          html_nodes("#REVIEWS .ui_bubble_rating") %>%
          as.character() %>%
          substr(38,39) %>%
          as.numeric()
        rating <- rating_wrong/10
        rating_v <- c(rating_v, rating)

        date <- reviews %>%
          html_node(".rating .ratingDate") %>%
          html_attr("title") %>%
          as.Date('%d %B %Y')
        date_v <- c(date_v, date)

        review <- reviews %>%
          html_node(".entry .partial_entry") %>%
          html_text()
        review_v <- c(review_v, review)
    }
tripadvisor <<- data.frame(id_v, headline_quote_v, rating_v, date_v, review_v)
}

all_pages(tripadvisor_urls)

当我查看生成的数据帧时,我看到有重复项:

duplicated(tripadvisor)

我做错了什么?我想这与不断向向量添加新元素有关。最好的解决方法是什么?

注意:我已请求TripAdvisor的许可,因此我没有违反他们的服务条款。