Figure 5

Disentangling functional flows. (a) We illustrate the strikingly distinct views on the functional organisation of a city extracted by isolating intra- or inter-layer flows. These maps outline the different “cities within the city” which we isolate by decoupling the urban flows into activity-aware multilayer networks. (b) We define the multilayer networks of human flows for each city (encoded by color) by stratifying flows according to different macro-categories used in this work (see Methods). Each point corresponds to integration and segregation measured after removing a specific layer of activities. The letter ‘T’ marks values associated to the removal of the transport layer, which strongly influence the urban functional connectivity (see Fig. 6). (c) Average functional integration for different activity categories. We observe a relationship between the average distance covered D in movement inside one layer and the value of integration (see Additional file 1, Fig. 7 for segregation). The regression is done excluding the outlier the unclassified venues “unknown” which removal appears not to influence a city’s functional integration