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Web

One of the most fundamental skills is the ability to select portions of an object layer.

SELECTION of OBJECTS

Object layers include a coverage of either points, lines or areas. It is sometimes useful to work with an entire layer of information, but more often than not, only a portion of the data are relevant to the work at hand.

There is a multitude of ways in which subsets can be designated. These include selection by one or more characteristic of the attached attribute data (e.g., select all census tracts with average incomes between $50,000 and $60,000 and more than half of adults college educated); by location (e.g., select all schools on the 50-year floodplain), or by distance (e.g., all residents within 1,000 feet of designated highways). Selection can also be done by pointing, by sketching, by intersecting lines, by comparing other selection sets, and so on. Combine this with selecting subsets, selecting various layers, bookmarking selections, adding to sets, inverting selections, seleting by graphics, etc., and you gain powerful command of your data layers.

A selected set can then be exported to create a new layer layer or worked with independently for maping or analysis. Students in G&ES 391 will learn to select objects and then to use these selected sets.