• Theero@lemmy.world
    185·
    11 months ago

    How is supposed to be interpreted? For example Helsinki is right on the coast and sure as shit hasn’t as many roads going south in to the drink compared to other directions

        • zaphod@feddit.de
          7·
          11 months ago

          Just read the study? They modelled street networks as undirected graphs, one-way streets are treated like all other streets, as their directionality isn’t considered.

          Street networks are typically modeled as graphs where nodes represent intersections and dead-ends, and edges represent the street segments that link them (Barthelemy and Flammini 2008; Cardillo et al. 2006; Lin and Ban 2013; Marshall et al. 2018; Porta et al. 2006). These edges are spatially embedded and have both a length and a compass bearing (Barthelemy 2011). The present study models urban street networks as undirected nonplanar multigraphs with possible self-loops. While directed graphs most-faithfully represent constraints on flows (such as vehicular traffic on a one-way street), undirected graphs better model urban form by corresponding 1:1 with street segments (i.e., the linear sides of city blocks). While many street networks are approximately planar (having relatively few overpasses or underpasses), nonplanar graphs provide more accurate models by accommodating those bridges and tunnels that do often exist (Boeing 2018c; Eppstein and Goodrich 2008).

        • amorpheus@lemmy.world
          5·
          11 months ago

          Even if they were counted accurately, usually there is another one way road nearby and which is going the other direction. So I doubt it would have a meaningful impact in the visualization.

    • KazuyaDarklight@lemmy.worldEnglish
      13·
      11 months ago

      It’s about the orientation of the roads, does the road align cleanly with the compass points or does it skew diagonal? So a clean N/S orientation results in a clean N/S line. When you look closely you’ll see the results are mirrored across the axis as a result.

      • electrorocket@lemmy.ml
        9·
        11 months ago

        Yeah, but the measurement is over total length of the roads, not the center of downtown. Every road runs the same distance in each direction, whether or not it’s a one way road.

    • Speiser0@feddit.de
      2·
      11 months ago

      It’s histograms, according to the paper:

      Fig. 5 Polar histograms from Fig. 4, resorted by descending φ from most to least grid-like (equivalent to least to greatest entropy)

      Fig. 4 Polar histograms of 100 world cities’ street orientations, sorted alphabetically corresponding with Table 1

      (A histogram shows how much there is of each kind, so here it’s how much road there is per direction.)