在 R 中解析 RSS 提要时绕过样式格式

Question

我正在尝试抓取并解析以下 RSS 提要 http://www.nestle.com/_handlers/rss.ashx?q=068f9d6282034061936dbe150c72d197。使用以下代码提取我需要的基本项目（例如，标题、描述、pubDate）没有问题：

library(RCurl)
library(XML)
xml.url <- "http://www.nestle.com/_handlers/rss.ashx?q=068f9d6282034061936dbe150c72d197"
script <- getURL(xml.url)
doc <- xmlParse(script)
titles <- xpathSApply(doc,'//item/title',xmlValue)
descriptions <- xpathSApply(doc,'//item/description',xmlValue)
pubdates <- xpathSApply(doc,'//item/pubDate',xmlValue)

我的问题是项目“描述”的输出不仅包括实际文本，还包括许多样式格式表达式。例如，第一个元素是：

descriptions[1]
[1] "<p><iframe height=\"322\" src=\"https://www.youtube-nocookie.com/embed/fhESDXnlMa0?rel=0\" frameBorder=\"0\" width=\"572\"></iframe><br />\n<br />\n<p><em>Nescafé</em> is partnering with Facebook to launch an immersive video, pioneering new technology just released for the platform.</p>\n<p>\nThe <em>Nescafé</em> <a class=\"externalLink\" title=\"Opens in a new window: Nescafé on Facebook\" href=\"https://www.facebook.com/Nescafe/videos/vb.203900255471/10156233581755472/?type=2&amp;theater\" target=\"_blank\">‘Good Morning World’ video</a> stars people in kitchens across the world, performing the hit song ‘Don’t Worry’ using spoons, cups, forks and a jar of coffee. Uniquely, viewers can rotate their smartphones through 360˚ to explore the video, the first time this has been possible on Facebook.</p>\n<p>\n“We know young coffee lovers pick up their phone at the start of every day looking to be entertained by real experiences. The 360˚ video allows us to be engaging in an innovative way,” said Carsten Fredholm, Senior Vice President of Nestlé’s Beverage Strategic Business Unit.\n</p>\n<p><em>Nescafé</em> recently teamed up with Google to offer the <a href=\"/media/news/pages/nescafe-google-virtual-reality-coffee-experience.aspx\">first virtual reality coffee experience</a> through the <em>Nescafé 360˚</em> app. It also became the first global brand to <a href=\"/media/news/pages/nescafe-moves-to-tumblr.aspx\">move its website onto Tumblr</a>, to strengthen connections with younger fans by allowing them to create and share content.</p>\n<p>The Nestlé brand is one of only six globally to partner Facebook for the launch of this technology.</p></p>"

我可以想到一种正则表达式方法来替换不需要的字符串。但是，有没有办法直接通过 xpath 访问项目“描述”的纯文本元素？

非常感谢您对此问题的任何帮助。谢谢。

Answer 1

你可以这样做：

descriptions <- sapply(descriptions, function(x) {
  xmlValue(xmlRoot(htmlParse(x)))
}, USE.NAMES=FALSE)

给出（通过cat(stringr::str_wrap(descriptions[[1]], 70)）：

In a move that will provide young Europeans increased access to
jobs and training opportunities, Nestlé and the Alliance for YOUth
have joined the European Pact for Youth as founding members. Seven
million people in Europe under the age of 25 are still inactive -
neither in employment, education or training. The European Pact for
Youth, created by European CSR business network CSR Europe and the
European Commission, aims to work together with businesses, youth
organisations, education providers and other stakeholders to reduce
skills gaps and increase youth employability. As part of the Pact, the
Alliance for YOUth will focus on setting up âdual learningâ schemes
across Europe, combining formal education with apprenticeships and on-
the-job training to help match skills with jobs on the market. The
Alliance for YOUth is a group of almost 200 companies mobilised by
Nestlé to help young people in Europe find work. It has pledged to
create 100,000 employability opportunities by 2017 and has already met
half of this target in its first year. Luis Cantarell, Executive Vice
President for Nestlé and co-initiator of the European Pact for Youth,
said: âPromoting a cultural shift to dual learning schemes based on
business-education collaboration is at the heart of Nestléâs youth
employment initiative since its start in 2013. The European Pact for
Youth will help to build a skilled workforce and will tackle youth
unemployment.â Learn more about the European Pact for Youth and read
their press release.

在生成的文本中（几乎在所有descriptions 中）的各个点都有\n 字符，但您可以将gsub 去掉。