def data_sort(gdf,str):
    """
    sort the geodataframe by special string

    Parameters
    ----------
    gdf : geodataframe
        geodataframe of gnss data
    str: sort based on this string
    Returns
    -------
    geodataframe:
        geodataframe of gnss data after sorting
    """
    gdf = gdf.sort_values(by = [str])
    
    return gdf