What are some data sources with strong positive and negative correlations in feature and sample space?
A couple of spatio-temporal datasets are likely to exhibit this characteristic:


Transportation demand across different locations of a city over different hours of a day. While residential locations have high demand originating there in the morning hours, and low demand in the evening, the reverse is true of work locations. The demand pattern of these two location types will be negatively correlated, whereas that of two different residential locations (or two locations of the same type) will be positively correlated. From the point of view of hours, correlation between two morning hours will be positive, whereas between a morning and an evening hour will be negative.
Temperature pattern across days, for different cities across the world. Here, data for cities in the northern and southern hemisphere will be negatively correlated.