The holonote library offers tools to create, edit and persist
annotated regions for HoloViews.
An annotated region marks a region-of-interest that is overlaid on top
of the visual representation of a HoloViews element. Such a region has a
unique identifier as well as additional domain-specific information
associated with it. What holonote offers is a flexible way to
interactively work with these visual regions as well as tools to add,
update and delete whatever domain-specific information you want to
associate with them.
There are two primary components currently offered by holonote:
-
Annotators: These classes offer the ability to interactively define regions, add associated domain-specific information and then persist this information to a database. You can interactively add, delete and update these annotation regions as well as their associated domain-specific data. -
Editors: These tools are designed to let you interactively manipulate and edit the visual regions themselves. These regions are in fact HoloViews elements which means you can use these editors as generic edit tools for the corresponding HoloViews elements.
By default, annotators automatically persist any annotations you create to a local SQLite database file. This is a very convenient way to get started with your annotation task, allowing you to immediate begin the process of collecting useful information.
For production usage where you are investing significant resources authoring annotations, it is advisable that you define a custom connector to a more appropriate database system. You can also use connectors to load annotations from existing databases of annotation data.
Do not use the SQLite connector when deploying to production. It is intended for use only during local development. It is not designed to be particularly efficient, stable, or secure.
There are two particularly important pieces of terminology that are used throughout this library to be aware of:
- Regions: These denote the visual regions-of-interest with a final visual representation as a HoloViews element. These may be one or two dimensional, may have different visual representations for the same data (e.g. a point marker or a crosshair to mark a point in 2D space) and have different types:
- Points: A single value of interest in an N-dimensional space. For instance, on a time axis, this corresponds to a moment in time which may be represented visually as a vertical line. On an image, this can ve visually represented with a crosshair.
- Ranges: A range is an axis-aligned span between a start and end point. For instance, along a time axis, this corresponds to a time interval and on an image, this corresponds to a 2D box.
- Fields: These are the domain-specific component of the annotation
data, containing information that is not to be visualized by
holonote. These are defined by the user or application and can have arbitrary types and contents. A complete set of fields together with one or more regions constitutes an annotation.