def combine_text_columns(data_frame, to_drop):
    """ 
    Helper function to convert all text rows of data_frame to single vector 
    """
    
    to_drop = set(to_drop) & set(data_frame.columns.tolist())
    text_data = data_frame.drop(to_drop, axis=1)    
    text_data.fillna(' ', inplace=True)

    return text_data.apply(lambda x: " ".join(x), axis=1)