Return ID of nearest neigbhour

[mhesselbarth]

As discussed in #181 it would be cool if get_nearestneighbour() returns the focal ID and the neighbour ID.

[mhesselbarth]

d0ba3ea

@frederikvand
Okay, if you install the development version from the corresponding branch ("get_nearestneighbour"; see code below), there now is a new argument which allows you to return also the ID of the neighbouring patch. Because the function needs an already labelled landscape (using get_patches()), the patch IDs are different to all other lsm_ functions. They go from 1 to n for each class and are not continuously increasing for the whole landscape. Not really happy about this, but I don't see how to improve that at the moment.

library(landscapemetrics)
library(raster)

# # install development version
# remotes::install_github(repo = "r-spatialecology/landscapemetrics", 
#                         ref = "get_nearestneighbour")

# get e.g. patches of class 2
class_2 <- get_patches(landscape)[[2]]

# return distance and id 
# (watch out, different labelling to lsm_ functions and several nearest neighbours
# for some patches)
get_nearestneighbour(class_2, return_id = TRUE)
#> # A tibble: 16 x 4
#>    layer    id  dist id_neighbour
#>    <int> <dbl> <dbl>        <dbl>
#>  1     1     1  4.47            5
#>  2     1     2  4.47            3
#>  3     1     3  3.16            6
#>  4     1     4  2              12
#>  5     1     4  2               6
#>  6     1     5  3               7
#>  7     1     6  2               4
#>  8     1     7  3               5
#>  9     1     7  3               8
#> 10     1     8  3               7
#> 11     1     9  3              10
#> 12     1    10  2.83            4
#> 13     1    11  5.83           14
#> 14     1    12  2               4
#> 15     1    13  2.83            4
#> 16     1    14  3.16            4

^{Created on 2020-06-12 by the reprex package (v0.3.0)}

[mhesselbarth]

Will merge to master and close issue. Please reopen if needed.