What Problem Does This Solve?
Build up a collection of features a user is interested in and that contains only a subset of all the features available.
Why Use This Pattern?
Selecting multiple items is a common input mechanism to gain further insights into the associated data. It helps shifting the focus on the few relevant items out of the many features available. Different than the attribute or spatial filter where all the features that don’t apply to the criteria get removed from the map the selection highlights the desired features without hiding the remaining features.
When to Use This Pattern
Selections are used as input to another action, most commonly analytical calculations, editing, sharing, or export. One may want to calculate statistics of aggregated property values for a planned construction site or see average insured value for an area affected by natural hazard. Adding features to a selection set allows users to batch edit attributes or create focused reports.
What’s the Solution?
Provide a means to activate selection mode, typically by selecting a tool or toggling the mode of the map from navigation to selection. If multiple selection methods exist, the app will need to offer a toolbar with a mutually exclusive set of options.
Common selection options include:
- Single selection: this is the expected default selection that adds a non-selected feature into a selected feature and vice versa.
- Multiple selection by rectangle: click and drag a rectangle to select features
- Multiple selection by lasso: click and draw a line to enclose features inside the area being sketched out
Selection should always be additive except for single selection that allows users to unselect a single item. That means an option to explicitly clear the current selection is important to reset and start over.
Selected markers need change their appearance, in most cases using a highlight color like yellow or cyan or alternative symbology so they can be visually distinguished from not selected features of the same kind.
An effective method of displaying the collection is a Marker List.
Consider providing feedback on the count of currently selected features, this is helpful to remind users that features may have been selected outside the currently visible extent. For focused applications it is recommended to add action buttons to the Info Window for adding features to a selection, for example an application to report street light outages could show information about a street light in the Info Window and offering the option to add it to the list of broken street lights.