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Spatial neighbourhoods in the British National Grid index system

bng_kring.Rd

Identify neighbours in a hollow ring or solid disc at grid distance 'k' from a target BNG reference.

Usage

bng_kring(bng_ref, k, ...)

bng_kdisc(bng_ref, k, ...)

Arguments

bng_ref

an object of type BNGReference

k

numeric value measuring the number of grid squares traversed between the ring and input BNG reference

...

additional parameters. Not currently used

Value

list containing an unordered collection of objects of type BNGReference within the neighbourhood around the given grid reference.

Details

K-rings are hollow rings of grid squares at a grid distance k while k-discs are filled areas around a given grid square up to a grid distance k. bng_kdisc includes the given BNG Reference (i.e. the central grid square).

In the event that bng_ref is along the edge or corner of the valid BNG area, then any return BNG references of the ring/disc outside the valid BNG range will not be returned.

Examples

bng_kring(as_bng_reference("SU1234"), 1)
#> [[1]]
#> <BNGReference[8] with Resolution=1km>
#> [1] <SU 11 33> <SU 12 33> <SU 13 33> <SU 11 34> <SU 13 34> <SU 11 35> <SU 12 35>
#> [8] <SU 13 35>
#> 

bng_kring(as_bng_reference("SU1234"), 3)
#> [[1]]
#> <BNGReference[24] with Resolution=1km>
#>  [1] <SU 09 31> <SU 10 31> <SU 11 31> <SU 12 31> <SU 13 31> <SU 14 31>
#>  [7] <SU 15 31> <SU 09 32> <SU 15 32> <SU 09 33> <SU 15 33> <SU 09 34>
#> [13] <SU 15 34> <SU 09 35> <SU 15 35> <SU 09 36> <SU 15 36> <SU 09 37>
#> [19] <SU 10 37> <SU 11 37> <SU 12 37> <SU 13 37> <SU 14 37> <SU 15 37>
#> 

bng_kdisc(as_bng_reference("SU1234"), 1)
#> [[1]]
#> <BNGReference[9] with Resolution=1km>
#> [1] <SU 11 33> <SU 12 33> <SU 13 33> <SU 11 34> <SU 12 34> <SU 13 34> <SU 11 35>
#> [8] <SU 12 35> <SU 13 35>
#> 

bng_kdisc(as_bng_reference("SU1234"), 3)
#> [[1]]
#> <BNGReference[49] with Resolution=1km>
#>  [1] <SU 09 31> <SU 10 31> <SU 11 31> <SU 12 31> <SU 13 31> <SU 14 31>
#>  [7] <SU 15 31> <SU 09 32> <SU 10 32> <SU 11 32> <SU 12 32> <SU 13 32>
#> [13] <SU 14 32> <SU 15 32> <SU 09 33> <SU 10 33> <SU 11 33> <SU 12 33>
#> [19] <SU 13 33> <SU 14 33> <SU 15 33> <SU 09 34> <SU 10 34> <SU 11 34>
#> [25] <SU 12 34> <SU 13 34> <SU 14 34> <SU 15 34> <SU 09 35> <SU 10 35>
#> [31] <SU 11 35> <SU 12 35> <SU 13 35> <SU 14 35> <SU 15 35> <SU 09 36>
#> [37] <SU 10 36> <SU 11 36> <SU 12 36> <SU 13 36> <SU 14 36> <SU 15 36>
#> [43] <SU 09 37> <SU 10 37> <SU 11 37> <SU 12 37> <SU 13 37> <SU 14 37>
#> [49] <SU 15 37>
#>