Parameter sweeps

Parameter sweeps iteratively update the values of parameters to exhaustively search through the parameter space for a simulation. EMOD does not currently support automated parameter sweeps. However, you can write your own code, such as a Python or MATLAB script, that iterates through the values you want for a particular parameter. This topic describes how to perform a parameter sweep.

For example, you can run simulations using a Python script that uses the parameter values specified in a JSON parameter sweep file to iteratively update the configuration or campaign parameter values. The IDM test team performs parameter sweeps as part of regression testing. See the following examples to see how this is implemented.

The following JSON example illustrates sweeping through configuration parameter values.

{
    "sweep" :
    {
        "path": "Vector/22_Vector_Garki_MultiCore_VectorMigration",
        "param_name" : "Run_Number",
        "param_values" : [ 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144 ]
    }
}

The following Python example illustrates how to update the configuration file with the above values. This is excerpted from the regression_test.py script in the Regression directory.

elif "sweep" in reglistjson:
    print( "Running sweep...\n" )
    param_name = reglistjson["sweep"]["param_name"]

    for param_value in reglistjson["sweep"]["param_values"]:
        os.chdir(ru.cache_cwd)
        sim_timestamp = str(datetime.datetime.now()).replace('-', '_' ).replace( ' ', '_' ).replace( ':', '_' ).replace( '.', '_' )
        if regression_id == None:
            regression_id = sim_timestamp

        configjson = ru.flattenConfig( os.path.join( reglistjson["sweep"]["path"], "param_overrides.json" ) )
        if configjson is None:
            print("Error flattening config.  Skipping " + simcfg["path"])
            ru.final_warnings += "Error flattening config.  Skipped " + simcfg["path"] + "\n"
            continue

        # override sweep parameter
        configjson["parameters"][param_name] = param_value

        campjson_file = open( os.path.join( reglistjson["sweep"]["path"],"campaign.json" ) )
        campjson = json.loads( campjson_file.read().replace( "u'", "'" ).replace( "'", '"' ).strip( '"' ) )
        campjson_file.close()
        configjson["campaign_json"] = str(campjson)

        report_fn = os.path.join( reglistjson["sweep"]["path"],"custom_reports.json" )
        if os.path.exists( report_fn ) == True:
            reportjson_file = open( report_fn )
            reportjson = json.loads( reportjson_file.read().replace( "u'", "'" ).replace( "'", '"' ).strip( '"' ) )
            reportjson_file.close()
            configjson["custom_reports_json"] = str(reportjson)
        else:
            configjson["custom_reports_json"] = None

        thread = runner.commissionFromConfigJson( sim_timestamp, configjson, reglistjson["sweep"]["path"], None, 'sweep' )
        ru.reg_threads.append( thread )
else:
    print "Unknown state"
    sys.exit(0)