Prepping Data For Usage Clustering
I believe your problem boils down to clustering time-series of different lengths. According to your question, you want the longer time-series of a power user to be considered similar to time-series of similar pattern but much shorter.
Therefore you should look into clustering techniques and distance metrics which allow for these properties. I don't know your language of choice but here are some of the many packages in R that you might find interesting :
- Fréchet distance - one of the packages offering this is kmlShape
- Dynamic Time Warping included in base R
- Permutation Distribution Clustering - package pdc
This would also solve your data formatting problem as to setting values to -1 or NULL would not be needed anymore. hth.