Deliverables

2.1. Milestone 1

Processing of monitoring station properties.

• Deadline:

  Mid-term sign-up session

• Points:

  4

Caution: Do not use the ‘representative output’ in your pytest tests. Representative output is provided to help you, but would not be part of a real contract. Moreover, you are working with real-time data which will change.

Task 1A: build monitoring station data

This task has been completed for you in the template repository.

1. In a submodule station, create a class MonitoringStation that represents a monitoring station, and has attributes:

   • Station ID (string)
   • Measurement ID (string)
   • Name (string)
   • Geographic coordinate (tuple(float, float))
   • Typical low/high levels (tuple(float, float))
   • River on which the station is located (string)
   • Closest town to the station (string)

2. Implement the methods __init__ to initialise a station with data, and __repr__ for printing a description of the station.

3. In the submodule stationdata implement a function that returns a list of MonitoringStation objects (for active stations with water level monitoring). To avoid excessive data requests, the function should save fetched data to file, and then optionally read from a cache file. The function should have the signature:

   def build_station_list(use_cache=True):

   The data should be retrieved from the online service documented at http://environment.data.gov.uk/flood-monitoring/doc/reference.

Demonstration program

In the program file Task1A.py, use the function stationdata.build_station_list to build a list of monitoring stations. Print the total number of stations, and a summary of the stations named ‘Bourton Dickler’, ‘Surfleet Sluice’ and ‘Gaw Bridge’. Representative output is:

Number of stations: 1840
Station name:     Bourton Dickler
   id:            http://environment.data.gov.uk/flood-monitoring/id/stations/1029TH
   measure id:    http://environment.data.gov.uk/flood-monitoring/id/measures/1029TH-level-stage-i-15_min-mASD
   coordinate:    (51.874767, -1.740083)
   town:          Little Rissington
   river:         Dikler
   typical range: (0.068, 0.42)
Station name:     Surfleet Sluice
   id:            http://environment.data.gov.uk/flood-monitoring/id/stations/E2043
   measure id:    http://environment.data.gov.uk/flood-monitoring/id/measures/E2043-level-stage-i-15_min-mASD
   coordinate:    (52.845991, -0.100848)
   town:          Surfleet Seas End
   river:         River Glen
   typical range: (0.15, 0.895)
Station name:     Gaw Bridge
   id:            http://environment.data.gov.uk/flood-monitoring/id/stations/52119
   measure id:    http://environment.data.gov.uk/flood-monitoring/id/measures/52119-level-stage-i-15_min-mASD
   coordinate:    (50.976043, -2.793549)
   town:          Kingsbury Episcopi
   river:         River Parrett
   typical range: (0.231, 0.971)

Task 1B: sort stations by distance

1. In the submodule geo implement a function that, given a list of station objects and a coordinate p, returns a list of (station, distance) tuples, where distance (float) is the distance of the station (MonitoringStation) from the coordinate p. The returned list should be sorted by distance. The required function signature is:

   def stations_by_distance(stations, p):

   where stations is a list of MonitoringStation objects and p is a tuple of floats for the coordinate p.

Tip: The distance between two geographic coordinates (latitude/longitude) is computed using the haversine formula. You could program the haversine formula, or you could use a Python library to perform the computation for you, e.g. https://pypi.org/project/haversine/.

Hint: Build a list of all (station, distance) tuples, and use the provided function utils.sort_by_key to produce a list that is sorted by the second entry in the tuple.

Demonstration program

Provide a program file Task1B.py that uses geo.stations_by_distance and prints a list of tuples (station name, town, distance) for the 10 closest and the 10 furthest stations from the Cambridge city centre, (52.2053, 0.1218). The closest 10 entries (e.g., x[:10]) in the list may be:

[('Cambridge Jesus Lock', 'Cambridge', 0.8402364350834995), ('Bin Brook', 'Cambridge', 2.502274086951454), ("Cambridge Byron's Pool", 'Grantchester', 4.0720438555077125), ('Cambridge Baits Bite', 'Milton', 5.115589516578674), ('Girton', 'Girton', 5.227070345811418), ('Haslingfield Burnt Mill', 'Haslingfield', 7.044388165868453), ('Oakington', 'Oakington', 7.128249171700346), ('Stapleford', 'Stapleford', 7.265694306995238), ('Comberton', 'Comberton', 7.7350743760373675), ('Dernford', 'Great Shelford', 7.993861351711722)]

and the furthest 10 (e.g., x[-10:]):

[('Boscadjack', 'Wendron', 440.0026482838576), ('Gwithian', 'Gwithian', 442.05491558132354), ('Helston County Bridge', 'Helston', 443.37824966454974), ('Loe Pool', 'Helston', 445.07184458260684), ('Relubbus', 'Relubbus', 448.64944322554413), ('St Erth', 'St Erth', 449.03415711886015), ('St Ives Consols Farm', 'St Ives', 450.0734690482922), ('Penzance Tesco', 'Penzance', 456.3857579793324), ('Penzance Alverton', 'Penzance', 458.5766422710278), ('Penberth', 'Penberth', 467.53367291629183)]

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