/// <summary>
        /// Trains the pipeline with data stored in a filename.
        /// </summary>
        public ScikitPipeline Train(string loaderSettings, string filename,
                                    string feature = "Feature", string label = null,
                                    string weight  = null, string groupId    = null)
        {
            _loaderSettings = loaderSettings;
            var loader = _env.CreateLoader(loaderSettings, new MultiFileSource(filename));

            return(Train(loader));
        }