Tubes and bubbles topological confinement of YouTube recommendations
(a) Induced recommendation graphs plotted according to number of nodes in the graph (N) and mean random walk entropy (). Points are colored according to number of views, on a log scale presented on the right. Solid green lines indicate medians, red dashed line is a linear regression of the distribution. Three points are marked in this latter line: one at each extremity and one in its middle. The three sample graphs (b), (c) and (d) are the closest ones to the three points indicated in the regression line of plot (a). Nodes (and adjacent edges) are colored according to the category of the video they correspond to.