I have temporal data of activity frequencies. I want to identify clusters in the data that indicate distinct periods of time with similar activity levels. Ideally I want to identify the clusters without specifying the number of clusters a priori.
What are appropriate clustering techniques? If my question does not contain enough information to answer, what are the pieces of information that I need to supply to determine appropriate clustering techniques?
Below is an illustration of the kind of data/clustering I am imagining: