Filling missing values with '-1'



Hello People,
When dealing with missing values in some cases I’ve seen people filling missing values with -1, what is the logic behind this?



it is just way of marking differently as some of the algo can differentiate the trends in missing values. specially when u dont know much about industry , reason of missing. on the other hand, if we impute values, we might be adding noise to the data in a way, so this strategy is being adopted & it works pretty well most of the time.


Thank you! Now what if there are already cells which have ‘-1’ in the same feature? In that case we’re saying that the values will be ‘-1’ right? What should be done in such a case?


you can use some other value too! such as -999