

def _prepare_topo_plot(inst, ch_type, layout):
    '"Aux Function'
    info = copy.deepcopy((inst if isinstance(inst, Info) else inst.info))
    if ((layout is None) and (ch_type is not 'eeg')):
        from ..channels import find_layout
        layout = find_layout(info)
    elif (layout == 'auto'):
        layout = None
    clean_ch_names = _clean_names(info['ch_names'])
    for (ii, this_ch) in enumerate(info['chs']):
        this_ch['ch_name'] = clean_ch_names[ii]
    info._update_redundant()
    info._check_consistency()
    if ((ch_type == 'grad') and (FIFF.FIFFV_COIL_VV_PLANAR_T1 in np.unique([ch['coil_type'] for ch in info['chs']]))):
        from ..channels.layout import _pair_grad_sensors
        (picks, pos) = _pair_grad_sensors(info, layout)
        merge_grads = True
    else:
        merge_grads = False
        if (ch_type == 'eeg'):
            picks = pick_types(info, meg=False, eeg=True, ref_meg=False, exclude='bads')
        else:
            picks = pick_types(info, meg=ch_type, ref_meg=False, exclude='bads')
        if (len(picks) == 0):
            raise ValueError(('No channels of type %r' % ch_type))
        if (layout is None):
            pos = _find_topomap_coords(info, picks)
        else:
            names = [ch.upper() for n in layout.names]
            pos = list()
            for pick in picks:
                this_name = info['ch_names'][pick].upper()
                if (this_name in names):
                    pos.append(layout.pos[names.index(this_name)])
                else:
                    warn(('Failed to locate %s channel positions from layout. Inferring channel positions from data.' % ch_type))
                    pos = _find_topomap_coords(info, picks)
                    break
    ch_names = [info['ch_names'][k] for k in picks]
    if merge_grads:
        ch_names = [(ch_names[k][:(- 1)] + 'x') for k in range(0, len(ch_names), 2)]
    pos = np.array(pos)[:, :2]
    return (picks, pos, merge_grads, ch_names, ch_type)

dataset/ETHPy150Open mne-tools/mne-python/mne/viz/topomap.py _prepare_topo_plot/VarMisuse@312/452 `n`->`ch`