Coefficient of variation of headway graph (real-time and historical)

[scrudden]

Create a graph which shows the coefficient of variation of headway in real-time for a route. This is the measure which can be used to look at the stability of a route.

[scrudden]

They system current calculates the headway of a vehicle when it arrives at a stop and then used this value along with the headway of all other vehicles to calculate to the coefficient of variation. These values are stored in Headway table. They are being set in

org.transitime.core.headwaygenerator.LastArrivalsHeadwayGenerator

This class needs to only included headway's for the current route in the calculation of the coefficient of variation. For Dynamic time trials this did not matter as they where on a single route.

[scrudden]

This will require two graphs one for real-time and one based on a start and end time.

[scrudden]

Code is on this branch. https://github.com/TheTransitClock/transitime/tree/tc_issue_13

[scrudden]

Now records number of vehicles on route as well as number with headway set in vehiclestate.

[scrudden]

First go at this. Need to smooth. It only plots values that where generated when each vehicle on the route has a valid headway.

[scrudden]

This is a smoothed version running this sql. It uses a running average (1800 seconds) and takes a sample every 10 minutes.

select max(avg), minutes from 
(
SELECT cast (extract(minute from h1.creationtime)+ extract(hour from h1.creationtime) * 60 as int) as minutes,
avg(h2.coefficientofvariation) as avg
FROM public.headway h1 JOIN public.headway h2 
ON h2.creationtime >= h1.creationtime - interval '1800 second'
AND h2.creationtime <= h1.creationtime  
AND  h1.routeid='12' AND h1.routeid=h2.routeid  AND h2.coefficientofvariation> 0 
AND h2.numvehiclesonroute=h2.numvehicles AND h1.creationtime BETWEEN '11-15-2017'  
AND TIMESTAMP '11-15-2017' + INTERVAL '1 day'   group by h1.creationtime 
ORDER BY  h1.creationtime
) hwc1
WHERE hwc1.minutes % 10 =0
GROUP BY minutes

[scrudden]

Revised based on comments from @simonberrebi. Now goes to two decimal places and using a line.