[Talk-us] Relation member order/structure; best effort worth it?

stevea steveaOSM at softworkers.com
Sun Jan 12 00:21:23 UTC 2014

A sidelong topic to "separate relations."

Volker and I just shared some email about how he uses JOSM automation 
to order relation elements, whereas I make some effort to "smarten 
them up."  This includes getting more, rather than fewer "route is 
ordered" messages from JOSM's relation editor's hover text.  It also 
includes "putting the list into a smaller sized set of well-ordered 
sub-routes" as a strategy.  (On my part, when I am manually 
re-ordering relation elements, especially when the route has branches 
and/or loops).

My argument is that "downstream algorithms" (whether by human effort 
or software robot) are often going to try to smarten up this route 
relation to a single path (or a subset of that, like sorting 
algorithms do with subsets of sorted lists).

Fascinating, no?  Does "smartening up" a data structure like "closer 
to a single path" (or close via many sorted sub-paths) tend towards 
coding for the renderer?  Or downstream software routing algorithms? 
Is there anything wrong with trying to write neat, better-organized 
data?  If we can, why wouldn't we?  (Cost of time/effort, perhaps). 
But even if only entities during the "while" can use it, and even if 
the relation in the meantime is essentially ephemeral?

Conversations like these help us hone in on a certain truth, or at 
least efficiency, yes?  In short, shouldn't we try to write neat data 
(if it isn't much extra effort)?  How can we get a nice "Pow!" for 
that buck?

We use shared data, after all.  The data I write today get used 
tomorrow, even though they might not next week.  But they might get 
used smartly (with less effort, quicker...) if I invest a bit of 
smarts right now.  Maybe that is automation (JOSM plug-in, bot, DWG 
consensus...) maybe that is a bit of human manual effort where it 
might make a difference.  Where does it make a difference?  OSM can 
be a deep place sometimes.

A lot of the conversations here are an attempt at agreement among 
structure and tagging.  Good for us.


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