Indexing Project: Applying Requirements

Using the shapefiles required to satisfy my requirements, I selected from each the lines/polygons that met my requirements. For example, using the landforms shapefile I selected polygons by attribute any type of mountains and then created a new layer from the selected set. To the left is a summary of the modified layers I used as the result of selection sets by attributes.

I began with the places points layer, which included 150,920 places. I later discovered this was a mistake, since these places included specific places such as neighborhoods that were not listed in census data. Thanks to advice from Dr. Howenstein, I was able to recover from this mistake by performing a spatial join with the placarea layer after my requirements had been applied.

First Requirement: Places within MSAs where >10% of commuters walk, bike, or use public transit as their primary means of transportation. To accomplish this, I tallied up the commuters that used a preferred method of transportation and divided that sum by the totals of all methods of transportation. Performing a spatial join between the places layer and the selection of favorable transit MSAs, resulted in the map to the left. This was a good limiting requirement, as shown by the map, restricting places less than 40 metropolitan areas.

Second Requirement: Places known to have a dry climate. I performed a spatial join between the layer created from the results of the first requirement and the selection layer of climates that were arid, semi-arid, or semi-humid.

Third requirement: Places within 100 miles of any type of mountains. Using the layer resulting from the second requirement, I performed a spatial join between it and a selection of mountains from the landforms layer, including a 100 mile buffer.

Fourth Requirement: Places within 100 miles from the coast. Using the layer created from the results above, I performed yet another spatial join between it and the coasts layer including a 100 mile buffer. Originally I'd intended to include lakes over a certain area, but realized there was no impact to my results since all of the remaining places were already either near the coast or inland not near any lakes.

Results of applying my requirements: not surprisingly all of the places that met my requirements were located within MSAs in coastal California.