title: What is difference between eval_metric and feval in xgboost?
body: <p>What is difference between <code>feval</code> and <code>eval_metric</code> in xgb.train, both parametrs are only for evaluation purpose.</p>
  
  <p>Post from Kaggle gives some insight :</p>
  
  <p><a href="https://www.kaggle.com/c/prudential-life-insurance-assessment/forums/t/18473/custom-objective-for-xgboost" rel="noreferrer">https://www.kaggle.com/c/prudential-life-insurance-assessment/forums/t/18473/custom-objective-for-xgboost</a></p>