Heat map of happiness in Milan.
(a) The map shows the intensity of happiness score of each area. Red areas have high happiness scores, while blue areas have low happiness scores. (b) The figure identifies the happiness category (happy, unhappy, or neutral) of each cell. We discretized the happiness score for areas. We considered the areas with the highest 15% happiness scores as happy areas, while the areas with the lowest 15% happiness scores as unhappy areas. Remaining areas are considered as neutral areas.