Add departure headings calculation

[nataliejschultz]

In reference to #202:
Previously, generate_dataset would calculate the arrival heading using the preset osmnx .bearing method, while departure headings were set to None.

This PR adds two functions written by @nreinicke:

1. calculate_bearings, which passes in linestrings and determines what to do with the coordinates based on the number of lat lon pairs
2. compass_heading, which calculates a compass bearing based on two lat lon pairs

These functions replace the osmnx method used previously, rather than using osmnx for arrival and the functions for departure. Both headings are added to the same data frame and output to edges-headings-enumerated.csv

[nreinicke]

This is looking great! I left a couple of small comments but I like how simple you've kept this

[nreinicke]

Could we move these functions into the utils module?

[nataliejschultz]

Could we move these functions into the utils module?

Moved with commit b9f7726

[nreinicke]

I appreciate the attribution but I'm okay if we omit them 🙂

[nataliejschultz]

I added the two functions to utils.py and changed the relevant command:

headings = [utils.calculate_bearings(i) for i in e.geometry.values]

For testing these changes locally, I added a name == main if statement to the bottom of the file with parameters to run:

if __name__ == '__main__':
    g = ox.graph_from_place("Denver, Colorado, USA", network_type="drive")
    testing_changes = generate_compass_dataset(g, 'testing-terminal')

Ran with python ./routee-compass/python/nrel/routee/compass/io/generate_dataset.py in terminal. After cd-ing into the testing-terminal output directory and using gunzip, here's what the top of the file looks like:

(base) nschultz-35728s:testing-terminal nschultz$ gunzip edges-headings-enumerated.csv.gz 
(base) nschultz-35728s:testing-terminal nschultz$ head edges-headings-enumerated.csv
arrival_heading,departure_heading
111,112
139,131
127,122
124,95
91,90
270,270
89,89
0,0
269,269

All is well!

[nataliejschultz]

@nreinicke tests failed because the runner couldn't find utils, so I changed the import utils that worked on my machine to the more universal:

from nrel.routee.compass.io import utils

in commit b6cbd62. Hopefully this solves it!

[nreinicke]

Excellent, looks good!