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UrbanAnalyst / dodgr

Distances on Directed Graphs in R
https://urbananalyst.github.io/dodgr/
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oneway flag not carried through to dodgr_streetnet_sc #153

Closed mpadge closed 3 years ago

mpadge commented 3 years ago

:bug: uncovered via #152

mpadge commented 3 years ago

Nope, that's actually intentional. oneway-ness is converted to a structural part of the network through only duplicated those edges which are not oneway, and otherwise only keeping the oneway edges intact as single (not duplicated) edges.

nataliamush commented 1 month ago

Hi! First of all, thanks for this great package. Just wanted to note that I couldn't find info on how one-ways were handled in the documentation (for e.g. weight_streetnet) so I wasn't sure if I need to duplicate/reverse streets myself, or if that's included in the function. Having found this issue I'm now reasonably certain that I don't need to do something like this as pre-processing like I might with a package like sfnetworks:


duplicates <- roads %>% filter(oneway != 'yes' | is.na(oneway)) # to deal with one-ways correctly, I need to duplicate all the two-ways to allow directed graphs to still travel down them

reversed_duplicates <- st_reverse(duplicates)

roads_with_dup <- rbind(roads, reversed_duplicates)

but it would be really helpful to have the handling of oneways somewhere in the docs! Thanks!

mpadge commented 1 month ago

Thanks for asking @nataliamush. It's an interesting question, and one that, from a technical perspective, shouldn't be necessary at all. The package is called "Distances on Directed Graphs" = DoDgr, which means that one-way links are always handled appropriately as such. But in the meantime so many equivalent options, including everything in python via osmnx and networkx, as well as any sf-based stuff in python, R, whatever, can not appropriately handle one-way links. So, from a graph-theoretic perspective, it's so implicit it doesn't need stating, but from the perspective of the current software ecosystem(s) of this kind of stuff ... I get your point.

If you can think of a good place to mention that, feel free to submit a pull request to improve the docs. Thanks!

nataliamush commented 1 month ago

Haha, fair! I'll look and submit a PR. Thanks again!