sftime - Githubissues

r-spatial / sftime

time extension to sf objects

https://r-spatial.github.io/sftime/

Apache License 2.0

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sftime #1

Open edzer opened 5 years ago

edzer commented 5 years ago

@luukvdmeer following up on our workshop during the OpenGeoHub summer school, I started a fresh repo for sf time objects. It's pretty empty still; for initial support we can think of methods for package gstat (all *ST functions; @bengraeler) and for st_join methods with stars objects; see also https://github.com/appelmar/gdalcubes_R/issues/26 for sampling a data cube along a trajectory.

luukvdmeer commented 5 years ago

Great! For me mainly the st_join method with stars objects looks very interesting and fits nice into the work I am doing on data cubes now in Salzburg. I would like to work on that as a start!

Just to make clear what your view on the scope of the package is (I know this is just a start and it might change over time):

As I understood, we are now mainly looking for a 'modern' alternative for what used to be the STIDF class in spacetime, since stars is already suitable for the STFDF and STSDF classes, and trajectories handles the STTDF class?
This includes finding ways to represent both time instances and (open and closed) time intervals.
And - on the long term - implementing temporal predicates (https://www.mdpi.com/data/data-04-00086/article_deploy/html/images/data-04-00086-g001.png), similar to the spatial predicate functions in sf?

edzer commented 5 years ago

Yes; leaving trajectories on the side, for now, this is for time-stamped features.

Currently, time is a time stamp only; for Date one could interpret this as a "full day" (left-close, right-open), for POSIXct it is really a time instance IMO. If we want to represent time intervals, we need a class for this, I would take a list column with length two POSIXct values representing a single left-closed right-open interval: [from, to), nothing else. stars already has the ability to represent time as intervals. One could go all the way and allow a non-negative even number of values, indicating 0 or more intervals (0 for the missing interval).

Starting with st_join would be good, ignoring intervals in sftime objects first.

bniebuhr commented 3 years ago

Hi,

I've just found about this sftrack package: https://mablab.org/sftrack/ You may probably know, but I guess some parallels may be good!

edzer commented 3 years ago

Thanks for reminding! Yes, coercion methods from and to sftrack seem to be trivial and useful.