Compound Filter

A Compound Filter can be used to speed up a Property Filter. You can use a different Property Filter filter for each item class.

For example, suppose you want to find all closed LineString items (i.e. LineString items that form loops, like buildings in a map). You could use a Property Filter filter with the expression _closed&<>0, but this would be applied to all Text items as well as all LineString items. To speed up the operation you only want to apply the property expression to LineString items. So you can use a Compound Filter to immediately exclude all item classes except LineString.

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