I'm new to Machine Learning and I just came across the sci-kit package. On this interesting page there are many toy data sets used to test different clustering algorithms. Each data set has a unique pattern and some algorithms perform better than others depending on the data sets.
I want to ask why these data sets are chosen as tests for the algorithms? What are the properties for them to be suitable for use in testing? Are there any other data sets with common attributes that are used for the same purpose? Do they have certain names that I can read more about?