# Validation¶

During optimization, SMAC does not automatically evaluate all configurations on all instances. The validate-module provides a convenient way to do this after a configuration run is finished. You can specify a set of configurations and a set of instances, whereupon the validator will run every configuration on every instance. This is either done by calling the target algorithm - or it is estimated using an EPM. This functionality can be important when comparing default and incumbent, giving a best estimate of the actual quality of the incumbent or investigating the quality of the incumbents founds over the time of the optimization. Validation supports parallel computing, non-deterministic target algorithms and reusing results from runhistories.

Note

When evaluating the cost via target-algorithm runs (no EPM), runs should be reused from a given runhistory only on comparable hardware!

## Commandline¶

python smac-validate.py --scenario SCENARIO --trajectory TRAJECTORY --output OUTPUT [--configs CONFIG_MODE] [--instances INSTANCE_MODE] [--[no-]epm] [--runhistory RUNHISTORY] [--seed SEED] [--repetitions REPETITIONS] [--n_jobs N_JOBS] [--tae TAE]

Required:
• scenario: Path to the file that specifies the scenario THAT IS USED FOR THE VALIDATION.

• trajectory: Path to the trajectory of the SMAC-run.

• output: Path to save output-runhistory to.

Optional:
• instances: Which instances to validate on, train or test are defined in scenario. From: [train, test, train+test] Default: test

• configs: What configurations to validate. From: [def, inc, def+inc, wallclock_time, cpu_time, all] def and inc validate on default and/or incumbent. all validates on all configurations in the specified trajectory wallclock_time/cpu_time validate at cpu- or wallclock-timesteps of [max_time/2^0, max_time/2^1, max_time/2^3, …, default] Default: def+inc

• [no-]epm]: epm uses an EPM which is built upon the given runhistory to estimate the costs of the config/instance-pairs; no-epm evaluates the config/instance-pairs by actually running the target algorithm Default: no-epm

• runhistory: path to a runhistory. If specified, runs from the runhistory will not be re-evaluated. IMPORTANT: THIS MAY BE DIFFICULT WHEN USING DIFFERENT HARDWARE Default: None

• repetitions: for non-deterministic target algorithms, this option specifies the number of different seeds that are evaluated per config/instance-pair Default: 1

• n_jobs: if no-epm is used, this is the number of cores to use for evaluation in parallel Default: 1

• tae from [old, aclib], if no-epm is used, this specifies the format of the target algorithm (see tae) Default: old

• verbose_level: in [INFO, DEBUG], specifies the logging-verbosity. Default: INFO

• seed: seed to be used for validation

## Usage in Python¶

To validate directly in Python (e.g. to perform a validation immediately after an optimization), the Validator can be used. It provides two different methods, validate and validate_epm. Both return runhistories containing results for all desired config/instance-pairs. To validate an actual *SMAC*-object, there is also a method within SMAC (see also: SVM-example).