def cpu_usage_for_process(results, process):
    """
    Calculate the CPU percentage for a process running in a particular
    scenario.

    :param results: Results to extract values from.
    :param process: Process name to calculate CPU usage for.
    """
    process_results = [
        r for r in results if r['metric']['type'] == 'cputime' and
        r['process'] == process
    ]

    cpu_values = sum(r['value'] for r in process_results)
    wallclock_values = sum(r['wallclock'] for r in process_results)

    if wallclock_values > 0:
        return float(cpu_values) / wallclock_values
    return None