Generate ordered ids of OD pairs so lowest is always first This function is slow on large datasets, see szudzik_pairing for faster alternative

od_id_order(x, id1 = names(x)[1], id2 = names(x)[2])

Arguments

x

A data frame or SpatialLinesDataFrame, representing an OD matrix

id1

Optional (it is assumed to be the first column) text string referring to the name of the variable containing the unique id of the origin

id2

Optional (it is assumed to be the second column) text string referring to the name of the variable containing the unique id of the destination

Examples

x <- data.frame(id1 = c(1, 1, 2, 2, 3), id2 = c(1, 2, 3, 1, 4))
od_id_order(x) # 4th line switches id1 and id2 so stplanr.key is in order
#>   stplanr.id1 stplanr.id1.1 stplanr.key
#> 1           1             1         1 1
#> 2           1             2         1 2
#> 3           2             3         2 3
#> 4           2             1         1 2
#> 5           3             4         3 4