How do I control the categories tree structure in the Page URLs and Page titles reports?

By default, Matomo (Piwik) will report your Page URLs in ‘categories’, automatically constructed based on the slash character / as a delimiter.
For example, a Page with a URL « http://example.org/about/contact » will be reported under the category « about » in the Page URLs report. When you click on it it will open the pages inside this category, and show the stats for the subpage « contact ». This feature is very useful because it helps visualize which sections of your website have the most traffic, rather than having all your page URLs at the same level.

Enabling category structure in the Page titles report

This grouping feature also works with Page Titles, although it is disabled by default.
You can enable the feature by setting a delimiter to use for splitting your Page titles into categories.
Edit your config/config.ini.php file, and add the following to specify slash / as the delimiter:

[General]
action_title_category_delimiter = /

This can be useful for organize your pages into a easier to analyse structure, tracking custom flash events (« game / clickStart », « game / registerNewUser »), video events (« videos/ bestOf2011 / start », « videos/ bestOf2011 / pause »), etc.

In the Javascript tracking code, you can specify custom page titles by calling matomoTracker.setDocumentTitle() (Learn more about the JS Tracking API). For example, to track a custom page view when a user clicked on a button in your web app, you could write

matomoTracker.setDocumentTitle("ajax/click view button");
matomoTracker.trackPageView();