def get_region_dir(hparams):
    """Return brain region string that combines region name and inclusion info.

    If not subsampling regions, will return :obj:`'all'`

    If using neural activity from *only* specified region, will return e.g. :obj:`'mctx-single'`

    If using neural activity from all *but* specified region (leave-one-out), will return e.g.
    :obj:`'mctx-loo'`

    Parameters
    ----------
    hparams : :obj:`dict`
        must contain the key 'subsample_regions', else function assumes no subsampling

    Returns
    -------
    :obj:`str`
        region directory name

    """
    if hparams.get('subsample_regions', 'none') == 'none':
        region_dir = 'all'
    elif hparams['subsample_regions'] == 'single':
        region_dir = str('%s-single' % hparams['region'])
    elif hparams['subsample_regions'] == 'loo':
        region_dir = str('%s-loo' % hparams['region'])
    else:
        raise ValueError('"%s" is an invalid regioin sampling type' % hparams['subsample_regions'])
    return region_dir