I want to ask wich algorithm can I use to do a sequences classification , knowing that I have two classes (positive /negative), but training is done using data from one class only (positive).
Thank you
With only one class in your training set, this sounds more like an unsupervised learning problem. Maybe look into anomaly/outlier detection algorithms rather than more traditional binary classifiers.
Is impossible to determine a model when the data you have has only one class, does not matter if they sequences, transactions, people, etc. How can your model learn the differences between categories?
The possibility you have is to run a cluster analysis on your dataset and look which variables may help you find separations between individuals, but you have to make sure that eventually you can have positives and negatives in your dataset.