Implement RasterLinesJoin operation

[kellyi]

Overview

This PR implements the RasterLinesJoin geoprocessing operation used in MapShed.

~All the infrastructure's wired up and operation's returns a count, but the count's currently slightly off.~ This is fixed now: my initial implementation was double counting values because the same row/col cells would be visited multiple times; my second try undercounted cells because it tried to throw out cells which had already been visited, but didn't track the visited cells correctly.

Now, we initialize the TrieMap to have a key which is a tuple comprising

• a list of the raster values
• the pixel col/row
• the SpatialKey

var pixelGroups: TrieMap[(List[Int], List[Int], SpatialKey), Int] = TrieMap.empty

... and then we only count the cell if it hasn't already been visited in that tile

At the end we drop the cell col/row & SpatialKey...

.map { case ((key, _, _), value) => (key, value) }

...then group by the raster values and sum.

Connects #53

Testing

• get this branch, then ./scripts/server to run sbt ~reStart
• post the request json included in this zip file to :8090/run nlcd-streams-request-response.zip`
• verify that the output matches the expected response
• test the RasterGroupedCount, RasterAverage, and RasterGroupedAverage operations and verify that they still return the values expected, too.

[rajadain]

Taking a look now.

[rajadain]

Tested in MMW against identical runs on Staging: the values are identical. Great work!

[kellyi]

Wonderful! I'm going to make the adjustments suggested above, then test everything out again before merging.

[kellyi]

Made the changes suggested above & tested again on my local. Everything's still working as before. Going to merge this once the tests pass.

Thanks for your help with this!