I have to classify some data without any futher prediction (I just need the best clusters on the data). Do I still have to train-test-split my data or do a kfoldCV? And how do I evaluate my clustering algorithmes (kmeans, spectral, KNN, SOM etc..)? (I already looked the score function of my algorithmes, the KL, the silhouette, inter-intra classes distances) I think, doing statistic tests would be meaningless, because I don't split the data. Can you answer those questions? Many thanks