House Database

Written by Frédéric Haziza

Module documentation

The code to produce would typically start by importing the necessary functions and classes from the db module.

from db import HomeDB

# Initilizing the database
database = HomeDB('uppsala.sqlite')
database.connect()
selection = database.select('rooms > 1 and rooms < 3 and area > 58 and rent < 3000')
database.disconnect()

# Looping now through the selection
for home in selection:
	# Do something

# Then plot

The above code essentially initializes the database, fetches some selection, based on some criteria, and plots the result on a map. Yes, it’s visual, it’ fun.

You could use the template file db.py, that you have to complete.

You can of course look at the documentation from the sourcecode itself, using the help function.

$ python
>>> import db
>>> help(db.plot)

The plot function has a few keyword parameters.

plot(selection,
     output='selection.html',
     special=None,
     zoom=12,
     latitude=59.83732598851705,
     longitude=17.64549846959149,
     radius=5000)
	

    Outputs the selection to map file. Section is a list of HomeEntry.
    The center is given by latitude and longitude and marked on the map with a blue marker.
    The map draws a radius around the center.
    When the special is used, an extra green marker is ploted in the map.

For each home, it is possible to call the following functions:

home.get_location()

returns a pair (latitude,longitude) as a float tuple.

home.get_price()

returns the price that home was sold for, in sek.

home.get_area()

returns its surface in m².

For a list of homes, it is possible to sort it by price using the function below.

sort_by_price(homes, reverse=False)

returns the sorted list, starting from the cheapest home. If reverse is set to true, the list is instead sorted from expensive to cheap

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The haversine formula determines the great-circle distance between two points on a sphere given their longitudes and latitudes. This will be useful for filtering the selection using the radius.

$ python
>>> import db
>>> help(db.haversine)

Help on function haversine in module db:

haversine(lat1, lon1, lat2, lon2)
    Calculate the great circle distance (in m) between two points
    on the earth (specified in decimal degrees)