summary statistics to add

[anastassiavybornova]

• for each of the polygon layers, the number and percentage of kilometers of cycle node network within that layer
• for each of the point layers, the number and percentage of reached vs. unreached points
• for the elevation layer, the number and percentage of kilometers in each elevation category
• for the entire network, the number of nodes, stretches, and loops
• for the area covered by the network, the average node density

what else? suggestions very welcome. and how? suggestions equally welcome. i thought of having a separate script at the very end that computes all the statistics above; saves the result to a json; and then uses the results to make a series of png plots. (let's save ourselves the pdf fanciness for now - i would suggest to just point to the subfolder which will contain the png files)

[mszell]

For each point layer, also the density of points? (could be per area, but also per km - for example to know that every X km on average there is a toilet etc)