one hot encoding target variable in tree and non tree (knn) methods

Question

I am learning about label encoders, one hot encoding etc applied to datasets for classification via KNN and XGBoost type trees. However, I am a bit confused as to whether the target variable should be one hot encoded or not.

In my case, I have a dataframe which has 500x10 size and the last column is the target (for prediction) country column while the rest of the 499 columns contain floating point values. So, an example row:

feature1 ..... fetaure499 target
1.1  ......... 40.1       Germany
6.1  ......... 265.7       USA
8.1  ......... 98,7      Singapore

In this case, what is the optimal way to encode the target for: [1] KNN [2] tree based methods.

My relatively naive understanding says that one hot encoding is useful for the feature space while for the target such as this, i.e list of countries labelencoding should be enough. Is this true for this case? Are there any situations I need to aware of when the target has to be label encoded?

Thank you.

Answer 1

The answer depends on the library you are using. If you are using scikit - you wouldn't need to one hot encode the targets. Scikit handles it automatically.

If you were using keras to build a neural network, you might want to use one hot encoded labels because the built in loss function in keras (e.g categorical crossentropy) expects labels to be one hot encoded.

So both approaches work and ate a function of the library or tools you use.