Classification Report - Precision and F-score are ill-defined

Question

I imported classification_report from sklearn.metrics and when I enter my np.arrays as parameters I get the following error :

/usr/local/

Answer 1

It means that some labels are only present in train data and some labels are only present in test dataset. Run the following codes, to understand the distribution of train and test labels.

from collections import Counter
Counter(y_train)
Counter(y_test)

Use stratified train_test_split to get rid of the situation where some labels are present only in test dataset.

It might have worked in past simply because of the random splitting of dataset. Hence, stratified splitting is always recommended.

The first situation is more about model fine tuning or choice of model.