Apart from the influence of filter on visibility and displaying styles of features, using filter gives one more interesting possibility connected with selection of features.
At the menu command of the map browser window Selection+By Filter the system opens a dialog box “Selection by filter” shown at figure 37-6.
Figure 37-6. Dialog box “Selection by filter”
This dialog box permits controlling selection of features falling into some filter group. Only the features of the types for which the filter condition is specified are taken into account.
Five variants offered in the pane Operation with selection are the variants of performing selection described in chapter 13 “Feature selection”. By default the variant Set is offered. Other modes allow combining a set of features selected earlier with features which will be selected by filter using different methods.
Checkboxes in the pane Apply for filter result enable the user to indicate the features of which standard filter groups should be selected. By default the group True is offered, however, it is possible to choose any of the two other groups or a combination of groups.
After pushing the button OK the system performs selection. Later on the features selected by filter can be used as features selected by any other method: it is possible to view summary data in the information bar, browse linked table data, remove selected features, etc.
The command of selection by filter works successfully even in the case when the theme filter is turned off.
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