Selection Sets

GISDK provides many GISDK functions for creating, manipulating, and working with selection sets. GISDK lets you create and maintain any number of selection sets on every layer or view (for an introduction to Views, see Tables and Views). Selection sets are identified by name, and set names must be unique within a layer or view.

For example, in standard Maptitude every layer has a selection set named Selection. When you create another set, the first new set is called Selection:1, then Selection:2, and so on.

Selection sets on any view that is linked to a layer are available on any other view that is linked to the same layer. For example, suppose you do the following in Maptitude:

Open a geographic file of states
Open a dBASE file containing sales information by state
Join the state layer to the dBASE file to create a joined view

Any selection set you create on the joined view can also be used to access records in the states layer.

Most selection GISDK functions support four different selection methods, as described in the following table:

Method	What it does
Several	Replaces the existing set with the new selection
More	Adds the new selection to the existing set
Less	Removes the new selection from the existing set
Subset	Selects from the existing set those records that are in the new selection

All selection GISDK functions work on the current layer or view. You must set the layer or view before using the selection GISDK functions. Selection GISDK functions that do geographic searching on a layer require that the layer be in a map, not just in the workspace.

Here are GISDK functions for creating and managing selection sets:

GISDK Function	Summary
CreateSet()	Creates a new, empty set on the current view
DeleteSet()	Deletes a set from the current view
GetDisplayStatus()	Returns information on how features in a selection set are displayed on a map
GetLayerSetsLabel()	Returns the label used in the legend for the list of sets belonging to a layer
GetRecordCount()	Gets the number of records in a view or selection set
GetRecords()	Gets an array of record handles for a selection set
GetSelectAutoRedraw()	Indicates how maps are updated during selection operations
GetSelectDisplay()	Indicates whether selection operations update maps automatically
GetSelectInclusion()	Indicates the inclusion status for spatial selection
GetSetCount()	Gets the number of records in a set in the current view
GetSetIDs()	Gets an array of the IDs of elements in a set
GetSetPosition()	Gets the position of a selection set on the current map layer
GetSets()	Gets a list of the names of selection sets for a view
GetSetScale()	Gets the range of scales at which a selection set displays (autoscale)
GetSetScope()	Gets the scope of the features in a selection set
IsMember()	Tests whether a record is a member of a selection set
RenameSet()	Changes the name of a selection set
SetDisplayStatus()	Changes how features in a selection set are displayed on a map
SetLayerSetsLabel()	Changes the label used in the legend for the list of sets belonging to a layer
SetSelectAutoRedraw()	Controls how maps are updated during selection operations
SetSelectDisplay()	Controls whether selection operations update maps automatically
SetSelectInclusion()	Sets the inclusion status for spatial selection
SetSetPosition()	Sets the position of a selection set on the current map layer
SetSetScale()	Sets the range of scales at which a selection set displays (autoscale)

Here are GISDK functions for changing the elements in a selection set:

GISDK Function	Summary
CreateGroup()	Creates multiple selection sets of records, using the classification technology of CreateTheme()
CreateGroupByTheme()	Creates multiple selection sets of records, using an existing theme
SelectAll()	Selects all the records in the current view
SelectByCircle()	Selects map features that are located within a circle
SelectByCoord()	Selects the map feature nearest to a coordinate
SelectByIDFile()	Selects map features from a list of feature IDs stored in a file
SelectByIDs()	Selects map features from a list of feature IDs
SelectByMapWindow()	Selects map features within the current map window
SelectByQuery()	Selects records based on an SQL query
SelectByQueryFile()	Selects records based on an SQL query that is stored in a file
SelectByScope()	Selects the map features located within a scope
SelectByShape()	Selects the map features located inside a shape
SelectByVicinity()	Selects map features located in or near features in another layer or selection set
SelectNone()	Removes all records from a selection set
SelectRecord()	Adds the current record to a selection set
SelectNearestFeatures()	Selects a feature in the current layer nearest to each feature in another layer or selection set
UnselectRecord()	Removes the current record from a selection set
VerifyQuery()	Verifies whether an SQL query has the correct syntax

Here are GISDK functions for combining or reorganizing selection sets:

GISDK Function	Summary
SetAND()	Selects features that are in all of several input selection sets
SetOR()	Selects features that are in any of several input selection sets
SetXOR()	Selects features that are in only one of several selection sets
SetInvert()	Selects all features that are not part of another selection set
SetCopy()	Copies a selection set
SortSet()	Sorts the records in a selection set based on the values of one or more fields

Many GISDK functions identify a selection set using a string containing the view or layer name, a vertical bar, and the set name.

// Set the fill color for all states to be white

SetFillColor("States|", ColorRGB(65535, 65535, 65535))

// Set the fill color for selected states to be red

SetFillColor("States|Selection", ColorRGB(65535, 0, 0))

Note that when these GISDK functions refer to the entire layer or view, the string contains the view name and a vertical bar.