Add support for new classes in oe_get

[agila5]

After #35

• sf
• sfc_POLYGON
• sfc_LINESTRING
• sp objects

[agila5]

See also #129 (comment) for spatial matching using something different from a sfc_POINT

[agila5]

I plan to work on sfc_POLYGON and sfc_LINESTRING extensions during the weekend (for a new project). The main question here is: how to determine the matched geographical area when we are comparing a POLYGON with a LINESTRING or a POLYGON with a POLYGON? The problem is that a POLYGON or a LINESTRING could intersect two or more geographical areas determined by a provider.

The simplest solution should be "greatest overlapping area + a warning message", any other suggestion?

[Robinlovelace]

Good thinking @agila5. I'm confident that this code will handle all sf/sfc classes, finding all zones that completely contain the geographic object, regardless of whether that's a line, polygon or point cloud:

https://github.com/ITSLeeds/osmextract/blob/3b927dd66f006c00d63e12424614696af1fede63/R/gf_find.R#L35-L50

The code should automatically select the smallest area that matches to avoid it downloading the world after every geographic query!

[agila5]

Thanks, I will start from that code!

[Robinlovelace]

I'm happy to give this a go...

[Robinlovelace]

For now the following works : )

osm_luton = osmextract::oe_get(sf::st_centroid(region_luton))

[Robinlovelace]

Would be great for this to work for polygons also, just tried this:

buildings = osmextract::oe_get(study_area, layer = "multipolygons")
Error: At the moment there is no support for matching objects of class sf. Feel free to open a new issue at github.com/itsleeds/osmextract

[agila5]

Would be great for this to work for polygons also, just tried this:

The easy solution would be to take the centroid and then fall back to the sfc_POINT method, is that reasonable?

[Robinlovelace]

The easy solution would be to take the centroid and then fall back to the sfc_POINT method, is that reasonable?

I think even simpler than that would be an st_contains() that would work with any geometry type and also ensure that larger regions are selected, e.g. for roads that cross 2 regions. Are you up for giving it a go? Happy to take a look next week.

[Robinlovelace]

Done I think! Don't need to support the legacy sp class system IMO.

[agila5]

Ok! Then, I will close :)