border_segment does not return the right number of segments

[guyschvitz]

I noticed that border_segment does not return the right number of segments if the input is a multilinestring. This seems to be a problem with st_cast, which can be fixed when using st_line_merge first, as shown in the MWE below:

library(sf)
library(SpatialRDD)

## Load example data
ch <- st_as_sf(raster::getData(name = "GADM", country = "CHE", level = 1))
ch <- st_transform(ch, 2056)

zh <- ch[grepl("Zür", ch$NAME_1),]
ag <- ch[grepl("Aar", ch$NAME_1),]

pts <- st_as_sf(st_sample(rbind(zh, ag), 1000))
border <- st_intersection(st_boundary(zh), st_boundary(ag))

## Use border_segment to split up into 10 segments
test <- border_segment(pts, border, 10)

## This creates 143 instead of 10 segments
length(unique(test))

## Try again with st_line_merge
test2 <- border_segment(pts, st_line_merge(border), 10)

## This creates 10 segments
length(unique(test2))

By the way this package is great!

[axlehner]

Thanks a lot, Guy.
I will take care of that soon. First there are some other things to fix and then the package will also be on CRAN shortly. I leave the issue open until then.