[R] Removing polygons from shapefile of Scotland and Islands

[Nick Wray]

Hello  I have a shapefile of Scotland, including the islands.  The river
flow data I am using is only for the mainland and for a clearer and larger
map I would like to not plot Orkney and Shetland to the north of the
mainland, as I don't need them.

The map I have I got from
https://borders.ukdataservice.ac.uk/easy_download_data.html?data=infuse_ctry_2011

then I put the uk shapefile onto my laptop with no problems (I have sf
running)

the_uk<-st_read(dsn="C:/Users/nickm/Desktop/Shapefiles/infuse_ctry_2011.shp")

scotland<-the_uk[2,]

plot(scotland$geometry)

This gives me a nice map of Scotland  plus islands but obviously there are
lots of separate polygons and if I go into the points with something like

scot_pts<-unlist(as.data.frame(scotland$geometry))

it's not at all clear how I can get rid of the points I don't want as they
don't seem to be listed in any easy way to find where one polygon stops and
another starts

I am wondering whether this approach is right anyway or whether there is
some sf function which would allow me to identify the polygons I want -
essentially the big one which is the mainland without lots of elaborate
conversions and manipulations

Any pointers, thoughts etc much appreciated

Thanks Nick Wray

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