adding the --optimize-category to bigmler analyze

On Wed, Dec 24 2014, mmerce wrote:

>> @@ -587,6 +588,20 @@ def best_first_search(datasets_file, api, args, common_options,
>>          u.log_message(message, log_file=session_file, console=1)
>>  
>>  
>> +def extract_evaluation_info(evaluation, category):
>> +    """Returns the evaluation metrics for the chosen
>> +       category or the average.
>> +
>> +    """
>> +    evaluation = evaluation.get("model", {})
>> +    if category and PER_CLASS in evaluation:
>> +        eval_per_class = evaluation.get(PER_CLASS, {})
>> +        for class_evaluation in eval_per_class:
>
> because regressions won't have PER_CLASS

but the `if` says `if category and PER_CLASS in evaluation:`, so yo don't
enter that branch unless PER_CLASS is there, no?