This module is at the core of my weather station software. It stores data on disc, but without the overhead of a full scale database system. I have designed it to run on a small memory machine such as my Asus router. To minimise memory usage it only loads one day's worth of data at a time into memory.
From a "user" point of view, the data is accessed as a cross between a list and a dictionary. Each data record is indexed by a datetime object (dictionary behaviour), but records are stored in order and can be accessed as slices (list behaviour).
For example, to access the hourly data for last Christmas day, one might do the following:
from datetime import datetime
import DataStore
hourly = DataStore.hourly_store('weather_data')
for data in hourly[datetime(2008, 12, 25):datetime(2008, 12, 26)]:
print data['idx'], data['temp_out']
The module provides three classes to store different data. data_store takes "raw" data from the weather station, hourly_store, daily_store and monthly_store store processed data (see Process.py). All three are derived from the same core_store class, they only differ in the keys and types of data stored in each record.
Python software for USB Wireless WeatherStations © Jim Easterbrook.