private protected PredictionEngineBase(IHostEnvironment env, ITransformer transformer, bool ignoreMissingColumns,
SchemaDefinition inputSchemaDefinition = null, SchemaDefinition outputSchemaDefinition = null)
{
Contracts.CheckValue(env, nameof(env));
env.AssertValue(transformer);
Transformer = transformer;
var makeMapper = TransformerChecker(env, transformer);
env.AssertValue(makeMapper);
_inputRow = DataViewConstructionUtils.CreateInputRow <TSrc>(env, inputSchemaDefinition);
PredictionEngineCore(env, _inputRow, makeMapper(_inputRow.Schema), ignoreMissingColumns, inputSchemaDefinition, outputSchemaDefinition, out _disposer, out _outputRow);
}