Converting XML markup to annotations
====================================

Often, the best way (and sometimes the only way) to add a specific type of
annotation to a text is by "manually" adding it to the data. This is
frequently done with XML markup. For instance, the text that appears in the
:ref:`Text field` instance of
:ref:`figure 1 <converting_xml_markup_annotations_fig1>` below is segmented
into words by means of *<w>* tags whose *type* attribute indicates the "part
of speech" associated with each word (e.g. *DET*, *NOUN*, *PREP*, and so on).

.. _converting_xml_markup_annotations_fig1:

.. figure:: figures/text_field_xml_example.png
    :align: center
    :alt: Specifying annotations values using the label of Text field instances
    :figclass: align-center

    Figure 1: Sample text annotated using XML markup.

The role of widget :ref:`Extract XML` is to convert XML markup into annotated
segments (in the sense of Orange Textable). In its basic version (see
:ref:`figure 2 <converting_xml_markup_annotations_fig2>` below), the widget's
interface essentially requires the user to specify the name of the XML
tags that must be imported, namely *w* in this example. The **Remove markup**
checkbox indicates whether further markup (if any) detected *whithin*
imported tags must be removed (there is no further markup in this example, so
that this option has no effect here).

.. _converting_xml_markup_annotations_fig2:

.. figure:: figures/extract_xml_example.png
    :align: center
    :alt: Interface of the Extract XML widget
    :figclass: align-center

    Figure 2: Interface of the :ref:`Extract XML` widget.

After connecting the above :ref:`Text field` and :ref:`Extract XML` instances,
and the latter to an instance of :ref:`Display`, the reader can verify that
the resulting segmentation contains a segment for the content of each *<w>*
tag in the input text, and that this segment is annotated with key *type* and
value *DET*, *NOUN*, or *PREP* (the three first such segments are shown on
:ref:`figure 3 <converting_xml_markup_annotations_fig3>` below). Each
attribute-value pair of each XML tag has indeed been automatically converted
to a *{key: value}* annotation.

.. _converting_xml_markup_annotations_fig3:

.. figure:: figures/display_xml_annotations_example.png
    :align: center
    :alt: Annotations imported using Extract XML
    :figclass: align-center

    Figure 3: Annotations imported using :ref:`Extract XML`.

