I have a dataset with features such as last_visit_n_days_ago, last_purchase_n_days_ago. These features are unavailable for many rows, which might have an important predictive value. The question is what to put in these cells if I want to use a learning algorithm that does not support missing values. My options are:

  • super large number (e.g. 1e38) to
  • the maximal number available for this database, plus some margin. What can be a good margin in this case
  • something else

1 Answer 1


It depends on the model you are going to use. If it is tree-based, a value outside the existing range will suffice. This will, however, not work for all models (e.g. linear regression)

Other approaches to consider:

  • Drop the rows with missing values (if there aren't too many)
  • Fill them with the mean/median/most_frequent value
  • Fill them using another model like KNN (sklearn or impyute), or even more advanced model.

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