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Parse HTML and Extract Text Content

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This example shows how to parse HTML code and extract the text content from particular elements.

Parse HTML Code

Read HTML code from the URL /help/textanalytics using webread.

url = "/help/textanalytics";
code = webread(url);

Parse the HTML code using htmlTree.

tree = htmlTree(code);

View the HTML element name of the tree.

tree.Name
ans = 
"HTML"

View the child elements of the tree. The children are subtrees of 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="/help/textanalytics/ug/s_tid_gn_logo.html"><IMG alt="bat365" class="mw_logo" src="/images/responsive/global/pic-header-bat365-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="/login?uri=http:/help/textanalytics/index.html">Sign…

Extract Text from HTML Tree

To extract text directly from the HTML tree, use 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."

Find HTML Elements

To find particular elements of an HTML tree, use findElement. Find all the hyperlinks in the HTML tree. In HTML, hyperlinks use the "A" tag.

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

View the first few subtrees.

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

    <A class="svg_link navbar-brand" href="/help/textanalytics/ug/s_tid_gn_logo.html"><IMG alt="bat365" class="mw_logo" src="/images/responsive/global/pic-header-bat365-logo.svg"/></A>
    <A class="mwa-nav_login" href="/login?uri=http:/help/textanalytics/index.html">Sign In</A>
    <A href="/products_s_tid_gn_ps.html">Products</A>
    <A href="/solutions_s_tid_gn_sol.html">Solutions</A>
    <A href="/academia_s_tid_gn_acad.html">Academia</A>
    <A href="/support.html?s_tid=gn_supp">Support</A>
    <A href="/matlabcentral/s_tid_gn_mlc.html">Community</A>
    <A href="/company/events_s_tid_gn_ev.html">Events</A>
    <A href="/company/aboutus/contact_us.html?s_tid=gn_cntus">Contact Us</A>
    <A href="/store?s_cid=store_top_nav/and/amp;s_tid=gn_store">How to Buy</A>
    <A href="/company/aboutus/contact_us.html?s_tid=gn_cntus">Contact Us</A>
    <A href="/store?s_cid=store_top_nav/and/amp;s_tid=gn_store">How to Buy</A>
    <A class="mwa-nav_login" href="/login?uri=http:/help/textanalytics/index.html">Sign In</A>
    <A class="svg_link pull-left" href="/help/textanalytics/ug/s_tid_gn_logo.html"><IMG alt="bat365" class="mw_logo" src="/images/responsive/global/pic-header-bat365-logo.svg"/></A>
    <A href="/products_s_tid_gn_ps.html">Products</A>
    <A href="/solutions_s_tid_gn_sol.html">Solutions</A>
    <A href="/academia_s_tid_gn_acad.html">Academia</A>
    <A href="/support.html?s_tid=gn_supp">Support</A>
    <A href="/matlabcentral/s_tid_gn_mlc.html">Community</A>
    <A href="/company/events_s_tid_gn_ev.html">Events</A>

Create a word cloud from the text of the hyperlinks.

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

Get HTML Attributes

Get the class attributes from the paragraph elements in the HTML tree.

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>

Create a word cloud from the text contained in paragraph elements with class "category_desc".

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

See Also

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