DBAdapters – database adapters for statistics

Warning

the use the of a DB Adapter can reduce the performance of the Genetic Algorithm.

Pyevolve have a feature in which you can save the statistics of every generation in a database, file or call an URL with the statistics as param. You can use the database to plot evolution statistics graphs later. In this module, you’ll find the adapters above cited.

See also

Method GSimpleGA.GSimpleGA.setDBAdapter()

DB Adapters are set in the GSimpleGA Class.

class DBAdapters.DBFileCSV(filename='pyevolve.csv', identify=None, frequency=1, reset=True)

DBFileCSV Class - Adapter to dump statistics in CSV format

Example:

>>> adapter = DBFileCSV(filename="file.csv", identify="run_01",
                        frequency = 1, reset = True)

param filename:the CSV filename param identify:the identify of the run param frequency:  the generational dump frequency param reset:if is True, the file old data will be overwrite with the new

close()

Closes the CSV file handle

commit()

Stub

commitAndClose()

Commits and closes

insert(stats, population, generation)

Inserts the stats into the CSV file

Parameters:

• stats – statistics object (Statistics.Statistics)
• population – population to insert stats (GPopulation.GPopulation)
• generation – the generation of the insert

open()

Open the CSV file or creates a new file

class DBAdapters.DBSQLite(dbname='pyevolve.db', identify=None, resetDB=False, resetIdentify=True, frequency=1, commit_freq=500)

DBSQLite Class - Adapter to dump data in SQLite3 database format

Example:

>>> dbadapter = DBSQLite(identify="test")

When you run some GA for the first time, you need to create the database, for this, you must use the resetDB parameter:

>>> dbadapter = DBSQLite(identify="test", resetDB=True)

This parameter will erase all the database tables and will create the new ones. The resetDB parameter is different from the resetIdentify parameter, the resetIdentify only erases the rows with the same “identify” name.

Parameters:

• dbname – the database filename
• identify – the identify if the run
• resetDB – if True, the database structure will be recreated
• resetIdentify – if True, the identify with the same name will be overwrite with new data
• frequency – the generational dump frequency
• commit_freq – the commit frequency

close()

Close the database connection

commit()

Commit changes to database

commitAndClose()

Commit changes on database and closes connection

createStructure(stats)

Create table using the Statistics class structure

Parameter:stats – the statistics object

getCursor()

Return a cursor from the pool

Return type:the cursor

insert(stats, population, generation)

Inserts the statistics data to database

Parameters:

• stats – statistics object (Statistics.Statistics)
• population – population to insert stats (GPopulation.GPopulation)
• generation – the generation of the insert

open()

Open the database connection

resetStructure(stats)

Deletes de current structure and calls createStructure

Parameter:stats – the statistics object

resetTableIdentify()

Delete all records on the table with the same Identify

class DBAdapters.DBURLPost(url, identify=None, frequency=100, post=True)

DBURLPost Class - Adapter to call an URL with statistics

Example:

>>> dbadapter = DBSQLite(url="http://localhost/post.py", identify="test")

The parameters that will be sent is all the statistics described in the Statistics.Statistics class, and the parameters:

generation

The generation of the statistics

identify

The id specified by user

Note

see the Statistics.Statistics documentation.

Parameters:

• url – the URL to be used
• identify – the identify of the run
• frequency – the generational dump frequency
• post – if True, the POST method will be used, otherwise GET will be used.

close()

Stub

commit()

Stube

commitAndClose()

Stub

insert(stats, population, generation)

Sends the data to the URL using POST or GET

Parameters:

• stats – statistics object (Statistics.Statistics)
• population – population to insert stats (GPopulation.GPopulation)
• generation – the generation of the insert

open()

Stub