setParams() got an unexpected keyword argument 'lambda'

[WL1988]

When I try to involve the L2 regularization parameter into the xgboostregressor by specifying the lambda_ parameter, an error occurred indicating that "TypeError: setParams() got an unexpected keyword argument 'lambda'". Could you help me to fix it? Your kind help is greatly appreciated.

[sllynn]

Try with a trailing underscore, i.e. lambda_. I think this was renamed to avoid the clash with python's lambda reserved keyword.

[WL1988]

Try with a trailing underscore, i.e. lambda_. I think this was renamed to avoid the clash with python's lambda reserved keyword.

@sllynn Thank you very much for the advice. Actually, that's what I did to use 'lambda_', i.e., the parameter I used are "model = XGBoostRegressor(objective='reg:squarederror', numRound=100, eta=0.1, maxDepth=5, alpha=0.0, lambda_=1.0)", and then the aforementioned TypeError raised. I guess it is related to the code in the 'init' function of the class 'XGBoostRegressor' in below:
if "lambda_" in kwargs:
kwargs["lambda"] = kwargs.pop("lambda_")
self.setParams(**kwargs)"
In addition, I found that the parameter used for the L2 regularization in xgboost4j_spark is 'lambda' (ref: https://xgboost.readthedocs.io/en/latest/jvm/scaladocs/xgboost4j-spark/ml/dmlc/xgboost4j/scala/spark/XGBoostRegressor.html). The rename process of replacing 'lambda_' with 'lambda' is probably to ensure the parameter consistence with the scala code. Nevertheless, I don't know what I could do to fix it. Do you have any opinions on this? Thank you very much and look forward to your reply.