16. The non-transitory computer readable storage medium of claim 15 , further comprising: sampling a fixed number of the time windows in the segmenting and the generating steps.
16. The non-transitory computer readable storage medium of claim 15 , further comprising: sampling a fixed number of the time windows in the segmenting and the generating steps. 19. The non-transitory computer readable storage medium of claim 16 , further comprising selecting a predetermined number of locations based on the association strength as the footprints, the footprints parameterized by associated word type, time window, and the predetermined number.