Data Visualization Toolkit: Using JavaScript, Rails, and Postgres to Present Data and Geospatial Information (Addison-Wesley Professional Ruby Series) by Barrett Clark

Author:Barrett Clark [Clark, Barrett]
Language: eng
Format: azw3
Publisher: Pearson Education
Published: 2016-08-04T04:00:00+00:00

Finalizing the Matrix

Now that we have our matrix generator we need to put it to work. Go back to the Departure class and have it extend DepartureMatrix. Now DepartureMatrix#airports_matrix! becomes a class method in Departure. We just need to call it, like so:

Click here to view code image

def self.departure_matrix

sql = <<-SQL.strip_heredoc

SELECT origin, dest, count(*)

FROM departures

WHERE unique_carrier = 'AA'

GROUP BY 1, 2

ORDER BY 1, 2

SQL

counts = connection.execute(sql)

airports_matrix!(:counts => counts)

end

You can run this from the console to see what your matrix looks like. It should be a large array of arrays.

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