CR Database

The crdatabase module is used to read and/or update event information. It can be imported by the following statement:

>>> from pycrtools import crdatabase

The event information is organized in various nested information objects.

• Event information (Event)

  This contains the basic event information, such as the timestamp and the processing status of the event. It also includes the event information found by LORA. Each event is linked to at least one datafile information object.

• Datafile information (Datafile)

  This contains the information of a single data file, such as the file name and processing status, that is linked to an event. Each datafile is linked to one station information file.

• Station information (Station)

  The station information object contains information about the station, such as the station name and processing status. Each station contains links to various polarization information objects.

• Polarization information (Polarization)

  The polarization information object contains event information for a single polarization direction for a station in an event. It contains an extensive list of polarization specific parameters of the event.

Opening the database

Opening of a CR database is done by initiating a CRDatabase object

>>> dbm = crdatabase.CRDatabase('dbfilename.db')

which returns an object with which the database can be managed.

By default it is assumed that the CR database that is to be opened already exists, but it can be explicitly checked and created by adding the create=True attribute at the instantiation of the CRDatabase object, i.e.

>>> dbm = crdatabase.CRDatabase('dbfilename.db', create=True)

In the examples below we assume we have such a dbm object.

Navigating through the database

To obtain a list of eventIDs of events that satisfy particular criteria you can use the getEventIDs() method, e.g.:

>>> eventIDs = dbm.getEventIDs(status='NEW')

An event information object can then be obtained via:

>>> event = dbm.getEvent(id=eventIDs[0])

This event object will contain a list with datafile objects that can be looked up via:

>>> for datafile in event.datafiles:
...     datafile.summary()

where we used the summary() method to show in a human readable format what is inside the information object.

Modifying the database

Updating an information object

To store the modifications you have made to an information object to the database you need to write it explicitly to the database by using the write() command. By default this will not only save the information in the particular information object, but also its parameters and underlying information objects. E.g. the command:

>>> station.write()

will store the station information, the station parameters and all polarization information. You can suppress the writing of parameters and underlying information objects by applying the parameters=False and recursive=False attribute settings, respectively, e.g.:

>>> station.write(parameters=False, recursive=False)

Removing an event from the database

Warning

This is a powerful command, use it with caution!

If you want to remove an information item from the database, this means that the underlying also needs to be removed from the database. For this there are the deleteEvent(), deleteDatafile(), deleteStation() and deletePolarization() methods in CRDatabase.

>>> dbm.deleteEvent(id=1)

This will remove the event with eventID=1, all event parameters and all underlying information objects that are linked to it.