Figure 4

Projection of the songs’ feature vectors on a 2-dimensional PCA space. Individual songs are drawn with markers representing the activity group, and color-coded with their activity. Example songs close to the centroid of points for each activity are reported. Calm songs, such as those for sleeping and relaxing, are mostly located in the leftmost side of the PCA space; intense songs, such as those for exercising, sex, and partying are on the right; and vibrant songs, such as those for breakfast, lunch, dinner, and driving, are in between the calm and intense songs