change: calibration results "sort_by_score" behaves gracefully if no score_name is given (single objective optim).

[jmp75]

Problem

Relates to csiro-hydroinformatics/wila#16.

If using a yaml string for weighted objectives, the objective name is not the yaml string. One needs to guess the objective name

From a python wrapper, JB reports:

OBJECTIVE_ID_STR = "[{ Name: 'NSE', Weight: 0.5 },{ Name: 'LogNSE', Weight: 0.5 }]"
objective_name = 'NSE:0.5,LogNSE:0.5'
[other code here...]
objective = sc.create_objective(f'{sc_id}.OutflowRate', masked_flow_df, OBJECTIVE_ID_STR, cal_start_date, cal_end_date)
[other code here to run the calibration...]
calib_results.sort_by_score(objective_name)

Desired solution

calib_results.sort_by_score("") should figure out the name of the objective to sort on if this is a single objective per scores.

Waiting for a fix upstream via csiro-hydroinformatics/wila#16, we can add python logic emulating this.