def get_classmap(anno_data, classmap):
    """
    Find classmap from middle format annotation data
    :param anno_list: [{'size':(width, height), 'objects':[{'name': '', 'bndbox':[xmin,ymin,xmax,ymax]}, ...]}, ...]
    :param classmap: Existing class name and number map
    :return: {'a': 0, 'b':1 ,...}
    """
    for _, anno_obj in anno_data.items():
        objects = anno_obj['objects']
        for obj in objects:
            name = obj['name']
            if name not in classmap.keys():
                classmap[name] = len(classmap.keys())
    return classmap