I have a dataset where one of the features is a list. Example: [ { ... other features ... X: ['joey', 'monica', 'ross'] }, { ... other features ... X: ['chandler', 'rachel', 'joey', 'phoebe'] } ... more records ... ] Feature X in the example can be of different lengths(let's say [0,50]). The domain for the values in X is of 200 different values. How should I handle X? Thanks. **EDIT:** More information about what X is. I'm trying to cluster failed software tests. Each test might fail in a different component. X is a list of failed components. What I'm trying to understand is how to represent this list of failed components in the vector of each data point.