def get_feature_class(row, quantile_list):
    """
    Helper method for stratification. 
    Returns class label based on quantile boundaries.
    
    Parameters:
    --------------
    row:            int, data point or series entry
    quantile_list:  list with quantile measures
    
    Returns:
    --------------
    class:          int, range(0,len(quantile_list)) - determining class
    """
    if row <= quantile_list[0]:
        return 0
    for q in range(len(quantile_list) - 1):
        if row > quantile_list[q] and row <= quantile_list[q+1]:
            return q+1