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Синтаксический анализ HTML и извлечение текстового содержимого

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В этом примере показов, как проанализировать HTML кода и извлечь текстовое содержимое из конкретных элементов.

Синтаксический анализ кода HTML

Чтение HTML кода из URL- https://www.mathworks.com/help/textanalytics использование webread.

url = "https://www.mathworks.com/help/textanalytics";
code = webread(url);

Проанализируйте HTML кода с помощью htmlTree.

tree = htmlTree(code);

Просмотрите HTML элемента имя дерева.

tree.Name
ans = 
"HTML"

Просмотрите дочерние элементы дерева. Дети являются поддеревьями tree.

tree.Children
ans = 
  4×1 htmlTree:

    " "
    <HEAD><TITLE>Text Analytics Toolbox Documentation</TITLE><META charset="utf-8"/><META content="width=device-width, initial-scale=1.0" name="viewport"/><META content="IE=edge" http-equiv="X-UA-Compatible"/><LINK href="/includes_content/responsive/css/bootstrap/bootstrap.min.css" rel="stylesheet" type="text/css"/><LINK href="/includes_content/responsive/css/site6.css?20180314" rel="stylesheet" type="text/css"/><LINK href="/includes_content/responsive/css/site6_lg.css?20180314" media="screen and (min-width: 1200px)" rel="stylesheet"/><LINK href="/includes_content/responsive/css/site6_md.css?20180314" media="screen and (min-width: 992px) and (max-width: 1199px)" rel="stylesheet"/><LINK href="/includes_content/responsive/css/site6_sm+xs.css?20180314" media="screen and (max-width: 991px)" rel="stylesheet"/><LINK href="/includes_content/responsive/css/site6_sm.css?20180314" media="screen and (min-width: 768px) and (max-width: 991px)" rel="stylesheet"/><LINK href="/includes_content/responsive/…
    " "
    <BODY id="responsive_offcanvas"><!-- Mobile TopNav: Start --><DIV class="header visible-xs visible-sm" id="header_mobile" translate="no"><NAV class="navbar navbar-default" role="navigation"><DIV class="container-fluid"><DIV class="row"><DIV class="col-xs-12"><DIV class="navbar-header"><BUTTON class="navbar-toggle topnav_toggle" data-target="#topnav_collapse" data-toggle="collapse" type="button"><SPAN class="sr-only">Toggle Main Navigation</SPAN><SPAN class="icon-menu"/></BUTTON><A class="svg_link navbar-brand" href="https://www.mathworks.com?s_tid=gn_logo"><IMG alt="MathWorks" class="mw_logo" src="/images/responsive/global/pic-header-mathworks-logo.svg"/></A></DIV></DIV></DIV><DIV class="row visible-xs visible-sm"><DIV class="col-xs-12"><DIV class="navbar-collapse collapse" id="topnav_collapse"><UL class="nav navbar-nav" id="topnav"><LI class="headernav_login"><A class="mwa-nav_login" href="https://www.mathworks.com/login?uri=http://www.mathworks.com/help/textanalytics/index.html">Sign…

Извлечение текста из HTML

Чтобы извлечь текст непосредственно из HTML, используйте extractHTMLText.

str = extractHTMLText(tree)
str = 
    "Text Analytics Toolbox™ provides algorithms and visualizations for preprocessing, analyzing, and modeling text data. Models created with the toolbox can be used in applications such as sentiment analysis, predictive maintenance, and topic modeling.
     
     Text Analytics Toolbox includes tools for processing raw text from sources such as equipment logs, news feeds, surveys, operator reports, and social media. You can extract text from popular file formats, preprocess raw text, extract individual words, convert text into numerical representations, and build statistical models.
     
     Using machine learning techniques such as LSA, LDA, and word embeddings, you can find clusters and create features from high-dimensional text datasets. Features created with Text Analytics Toolbox can be combined with features from other data sources to build machine learning models that take advantage of textual, numeric, and other types of data."

Поиск элементов HTML

Чтобы найти конкретные элементы HTML, используйте findElement. Найти все гиперссылки в HTML. В HTML гиперссылки используют тег «A».

selector = "A";
subtrees = findElement(tree,selector);

Просмотрите первые несколько поддеревьев.

subtrees(1:20)
ans = 
  20×1 htmlTree:

    <A class="svg_link navbar-brand" href="https://www.mathworks.com?s_tid=gn_logo"><IMG alt="MathWorks" class="mw_logo" src="/images/responsive/global/pic-header-mathworks-logo.svg"/></A>
    <A class="mwa-nav_login" href="https://www.mathworks.com/login?uri=http://www.mathworks.com/help/textanalytics/index.html">Sign In</A>
    <A href="https://www.mathworks.com/products.html?s_tid=gn_ps">Products</A>
    <A href="https://www.mathworks.com/solutions.html?s_tid=gn_sol">Solutions</A>
    <A href="https://www.mathworks.com/academia.html?s_tid=gn_acad">Academia</A>
    <A href="https://www.mathworks.com/support.html?s_tid=gn_supp">Support</A>
    <A href="https://www.mathworks.com/matlabcentral/?s_tid=gn_mlc">Community</A>
    <A href="https://www.mathworks.com/company/events.html?s_tid=gn_ev">Events</A>
    <A href="https://www.mathworks.com/company/aboutus/contact_us.html?s_tid=gn_cntus">Contact Us</A>
    <A href="https://www.mathworks.com/store?s_cid=store_top_nav&amp;s_tid=gn_store">How to Buy</A>
    <A href="https://www.mathworks.com/company/aboutus/contact_us.html?s_tid=gn_cntus">Contact Us</A>
    <A href="https://www.mathworks.com/store?s_cid=store_top_nav&amp;s_tid=gn_store">How to Buy</A>
    <A class="mwa-nav_login" href="https://www.mathworks.com/login?uri=http://www.mathworks.com/help/textanalytics/index.html">Sign In</A>
    <A class="svg_link pull-left" href="https://www.mathworks.com?s_tid=gn_logo"><IMG alt="MathWorks" class="mw_logo" src="/images/responsive/global/pic-header-mathworks-logo.svg"/></A>
    <A href="https://www.mathworks.com/products.html?s_tid=gn_ps">Products</A>
    <A href="https://www.mathworks.com/solutions.html?s_tid=gn_sol">Solutions</A>
    <A href="https://www.mathworks.com/academia.html?s_tid=gn_acad">Academia</A>
    <A href="https://www.mathworks.com/support.html?s_tid=gn_supp">Support</A>
    <A href="https://www.mathworks.com/matlabcentral/?s_tid=gn_mlc">Community</A>
    <A href="https://www.mathworks.com/company/events.html?s_tid=gn_ev">Events</A>

Создайте облако слов из текста гиперссылок.

str = extractHTMLText(subtrees);
figure
wordcloud(str);
title("Hyperlinks")

Получение атрибутов HTML

Получите атрибуты класса из элементов абзаца в HTML.

subtrees = findElement(tree,'p');
attr = "class";
str = getAttribute(subtrees,attr)
str = 21×1 string array
    <missing>
    <missing>
    "add_margin_5"
    <missing>
    <missing>
    <missing>
    <missing>
    <missing>
    "category_desc"
    "category_desc"
    "category_desc"
    "category_desc"
    <missing>
    <missing>
    <missing>
    "text-center"
    <missing>
    <missing>
    <missing>
    "copyright"
    <missing>

Создайте облако слов из текста, содержащегося в элементах абзаца с "category_desc" классов.

subtrees = findElement(tree,'p.category_desc');
str = extractHTMLText(subtrees);
figure
wordcloud(str);

См. также

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